ON THE WATER
Feedback as you row
Follow bend, moment or handle force alongside oar speed as you row. Choose the curves and numbers that help you connect the catch, drive and release.
Explore the iOS app →Get to know your stroke.
Watch the stroke and its curves together. Use full screen for a closer look.
See how you load the oar, carry the drive and release the blade.
Record oar motion and loading, see live feedback on your iPhone, and review each stroke alongside GPS and boat movement after your row.
AFTER YOUR ROW
Review the whole workout
Compare strokes, pieces and group averages. See the GPS route, boat motion and stroke replay together when those recordings are available.
Explore cloud analysis →GET SET UP
Set up your oar
Assemble the kit, select your saved oar and connect its sensors. Guided alignment and a stiffness calibration keep the measurements tied to your setup.
Assemble your kit →START WITH YOUR PHONE
Choose your phone.
iOS · ritmoForceCurve
Connect your saved oar, complete the guided alignment, and record the workout with live curves and metrics. Use two sensors per oar; connect four to record two oars.
iOS setup & recordingAndroid · WitMotion
Record your oar sensors in WitMotion. Add a separate Sensor Logger recording when you want phone motion and GPS in the report.
Android setup & recordingBoth recording paths use the same Cloud Analysis and interactive report. See pricing for available products and plans.
FROM THE OAR TO THE BOAT
Explore a recorded workout.
Open the example to explore oar curves, GPS and boat motion from one recorded workout. Follow individual strokes or compare averages, then use the boat-and-oar replay to see the movement.
Choose metrics by subject: Oar, Boat, GPS, Time and Body. Save your plot and replay setup to reuse on another workout. Boat movement needs a securely mounted phone; blade depth and water-contact trails depend on the recorded setup and supplied geometry.
MEASURE THE OAR YOU HOLD
Measure bend and motion on the oar.
Two sensors measure how the oar bends and moves. With the correct stiffness calibration and dimensions, the app uses that bend to calculate moment, force, work and power.
The motion measurement follows the shaft through the catch, drive and release. Sweep angle, blade rotation and loading describe different parts of the stroke; the metric guide explains each one.
How the measurements work →THE IPHONE APP
See your stroke.
Record your row.
Live curves and clear numbers on the water. Review all your workout metrics in tables and maps when you finish.
WHAT YOUR IPHONE CAN DO
Feedback during the row. Detail after it.
Follow the stroke
See the bend / moment / force curve with oar motion and selected metrics. Follow changes in power, rate and stroke shape as you row.
Choose what you see
Build a live rowing view with large metric tiles, curves or a mix of both. Choose the available measurements and use the question marks for explanations.
Bring the signals together
Combine the oar sensors with iPhone GPS and boat motion. Add heart rate from a connected source. Each measurement uses the inputs it needs.
Keep the whole session
Record work and recovery intervals, use the automatic piece timer, and save the workout with the oar settings used for that row.
Review your workout metrics
Review all your workout metrics in tables and maps. Explore the session’s numbers and route, and share available workout data.
Explore the workout
Upload from the app to explore workout metrics, tables and route maps in an interactive report.
Cloud Analysis →METRICS & CURVES
Find the measurement you need.
The core catalog is grouped by Oar, Boat, GPS, Time and Body. Bend / moment / force is presented together, with a question mark beside each item for its explanation.
Core metrics & curves
Oar
Metrics
Loaded stroke arc length (°) — explanation
Loaded oar sweep from confirmed load engagement to the end of the loaded drive.
Power (W) — explanation
Work per stroke divided by the complete catch-to-catch cycle time, including recovery. Requires calibrated bend and supported oar motion.
Power (W) = positive drive work (J) / stroke-cycle time (s)
Stiffness calibration scales the work and power values. A longer recovery reduces power for the same work per stroke.
PowerSplit (s/500 m) — explanation
Effort-equivalent 500 m pace calculated from positive oar power.
PowerSplit (s/500 m) = 500 × (2.80 / power in W)1/3
GPS pace describes travel over the ground. Wind, current, hull resistance and crew movement affect how oar effort relates to boat speed.
Mid-work position (%) — explanation
Position along the loaded stroke arc where half of the drive work has been completed. A value below 50% places more work earlier in the arc.
Peak bend position (%) — explanation
Position along the loaded stroke arc where shaft bend reaches its peak.
Catch miss (°) — explanation
Oar sweep from the catch to confirmed load engagement. The shaft may move and bend before sustained loading is established.
Finish wash (°) — explanation
Oar sweep from the loaded-drive endpoint to the feather threshold. It is zero when feathering itself defines the loaded-drive endpoint.
Release travel (°) — explanation
Oar sweep from the feather threshold to the finish reversal. It describes movement after feathering begins, separately from the end of the loaded drive.
Ratio — explanation
Recovery time divided by drive time. A value of 2 means recovery lasts twice as long as the drive.
Work per stroke (J) — explanation
Positive work accumulated as the loaded oar rotates through the drive. Requires the oar stiffness calibration.
Drive work (J) = ∫ moment (N·m) × dθ (radians)
Both the load and the angle through which it acts matter. A brief high peak and a longer steady pull can produce different work. Holding load without further sweep adds no sweep work.
Sweep arc (°) — explanation
Full oar sweep from catch to finish reversal, including unloaded movement.
Drive acceleration (°/s²) — explanation
Increase in handle rotation speed from load engagement to peak speed, divided by the elapsed time.
Power speed (m/s) — explanation
Effort-equivalent speed calculated from oar power. Measured speed over the ground is available under GPS.
Peak rotation speed (°/s) — explanation
Highest handle rotation speed during the drive.
Drive rotation speed (°/s) — explanation
Mean oar sweep speed during the drive.
Curves
Bend / moment / force (° · N·m · N) — explanation
Three views of loading through the drive: shaft bend, bending moment about the pin, and estimated handle force.
Moment (N·m) = Moment/Bend Factor (N·m/°) × bend (°)
Handle force (N) = moment (N·m) / pin-to-hand distance (m)
The Moment/Bend Factor converts measured bend to moment for the oar and sensor positions. Changing it scales moment, work and power while leaving stroke timing and measured angles unchanged. The saved inboard lever arm determines the estimated handle force.
For example, 300 N·m through a 1.0 m lever corresponds to 300 N of perpendicular force; through a 1.2 m lever it corresponds to 250 N.
The app’s Moment/Bend Factor (MBF) uses N·m/°. A saved bend factor (FBF) in J/°² uses the older coefficient: FBF = MBF × π/180; MBF = FBF × 180/π.
Oar identity, side, geometry, sensor positions, alignment and stiffness calibration must match the recording for comparable results. A report override changes that report’s calculations; the saved setup governs future recordings.
Oar speed (°/s) — explanation
Oar sweep rotation speed through the stroke. Positive is the drive direction; negative is recovery.
Blade bottom edge depth (cm) — explanation
Estimated vertical position of the blade’s bottom edge, using oar geometry and the feather/square transition. The squared blade extends deeper than the feathered blade.
Negative is down from the reference pin plane. The result depends on the saved geometry, supported oar inclination and boat-motion correction. Blade position, the animation’s waterline and immersed area are estimates; they do not directly measure water level or blade immersion.
Blade-tip depth (cm) — explanation
Estimated shaft-axis blade-tip position from oar inclination, outboard length and boat-motion correction. Requires supported oar geometry and phone motion.
Negative is down from the horizontal reference plane through the pin. The phone’s hull reference and oar alignment affect this estimate. It describes blade-tip position, not directly measured water immersion; the animation’s waterline and immersed blade area are also estimates.
Horizontal sweep angle (°) — explanation
Horizontal oar rotation with zero at the catch, showing the drive and recovery. Requires supported motion from the oar’s sensor pair.
Feather / square (−1 to +1) — explanation
Blade orientation through the stroke: +1 is square and −1 is feathered. The transition shows when the blade rotates between these positions.
Boat
Metrics
Distance check (cm) — explanation
Difference between the highest and lowest relative boat displacement during a complete catch-to-catch cycle. It uses the Relative boat distance curve from phone motion; GPS is not required.
Distance check (cm) = 100 × [max(x) − min(x)]
Here x is relative forward distance in metres, obtained by integrating relative boat speed and centering it around the cycle reference. This describes the range of the boat’s movement ahead of or behind that reference.
Speed check (m/s) — explanation
Difference between the highest and lowest relative boat speed during a complete catch-to-catch cycle. It uses phone motion; GPS is not required.
Speed check (m/s) = max(u) − min(u)
Here u is relative boat speed from gravity-corrected phone acceleration, centered on the cycle’s time-weighted mean. The check measures the full range of speed variation through the stroke.
Energy-loss check (V²) (%) — explanation
A model of speed variation based on squared fused ground speed across the complete stroke cycle, compared with steady travel at the same mean speed. It is not a direct measurement of rowing energy lost or water resistance.
For fused ground speed v(t) and cycle duration T, the time-weighted mean is:
μ = ∫₀ᵀ v(t) dt / T
Energy-loss check (%) = 100 × [∫₀ᵀ v(t)² dt − Tμ²] / (Tμ²)
Constant speed gives 0%. The calculation requires a complete supported cycle and positive mean speed. Current affects the ground-speed reference, so values should be interpreted in that context.
Set range (°) — explanation
Difference between the highest and lowest hull roll angles during the stroke cycle.
The phone’s orientation separates gravity from acceleration. Where a saved physical boat-level reference is available, it provides the level reference. Otherwise, neighbouring complete strokes establish a neutral gravity plane, using a 20-second local reference by default.
The range shows changes in set within the stroke. A local neutral plane follows the boat’s trim and does not establish absolute hull level.
Pitch range (°) — explanation
Difference between the highest and lowest bow-up/bow-down angles during the stroke cycle.
Phone orientation supplies hull attitude. Without a saved physical boat-level reference, the neutral plane comes from neighbouring complete strokes, using a 20-second local reference by default. This describes movement around local trim; slow trim and phone mounting tilt cannot be separated by that local reference alone.
Fused boat speed (m/s) — explanation
Ground speed combining GPS with phone acceleration to describe changes within the stroke. Zero means zero ground speed. Valid GPS speed is used when fusion is unavailable.
Current affects the ground-speed baseline. Relative boat speed uses a different reference: deviation around the stroke cycle’s mean speed.
Fused boat split (s/500 m) — explanation
500 m pace calculated from the displayed fused boat speed, including its GPS fallback. A valid positive speed is needed to show a split.
Heave excursion (cm) — explanation
Estimated range of vertical hull movement through the complete stroke cycle, from gravity-corrected phone motion.
It describes relative rise and fall around the cycle reference. It does not measure absolute height above the water or the waterline.
Minimum relative boat speed (m/s) — explanation
Lowest speed deviation relative to the stroke-cycle mean. A negative value means slower than that reference, not backward travel. Requires supported phone motion across the full cycle.
Curves
Forward acceleration (m/s²) — explanation
Gravity-corrected acceleration along the hull, filtered for viewing. Requires a phone fixed securely to the boat.
The phone’s orientation separates gravity from boat acceleration. Integrating this motion supplies the relative boat-speed and distance curves; supported orientation and a complete stroke cycle are needed for their check values.
Relative boat speed (m/s) — explanation
Speed variation through the stroke from gravity-corrected phone acceleration, centered on the cycle’s time-weighted mean.
Positive means faster and negative means slower than that reference. A negative value does not mean backward travel. Its full-cycle range gives Speed check; GPS is not required.
Relative boat distance (cm) — explanation
Relative forward displacement through the complete stroke cycle, calculated by integrating relative boat speed and centering the result around the cycle reference.
The curve shows the boat ahead of or behind that reference. Its full-cycle range gives Distance check; GPS is not required.
GPS
Metrics
GPS speed (m/s) — explanation
Speed over the ground derived from GPS positions. Zero means no ground travel. Water current affects this speed, so it differs from speed through the water.
GPS distance (m) — explanation
Distance traveled over the ground during the recording, calculated from GPS positions. It follows the ground track, including the effect of current.
GPS pace (s/500 m) — explanation
Time to travel 500 m at the measured GPS speed. A valid positive speed is needed to show a pace.
Piece split (s/500 m) — explanation
Pace for the current detected piece, calculated from its elapsed time and distance.
Piece distance (m) — explanation
Distance traveled in the current detected piece.
GPS heading (°) — explanation
Direction of travel clockwise from true north. Requires valid GPS data and enough movement to establish a course. It describes travel direction, independent of how the phone is mounted.
Time
Metrics
Stroke rate (spm) — explanation
Strokes per minute measured from successive confirmed catches.
Workout time (h:mm:ss) — explanation
Elapsed workout time.
Piece time (m:ss) — explanation
Elapsed time in the current detected piece.
Stroke ID — explanation
Identifier used to locate a stroke in the workout data.
Time (s) — explanation
Elapsed recording time at the stroke’s catch.
Body
Metrics
Heart rate (bpm) — explanation
Heart rate over the stroke interval, from a connected heart-rate source.
Calories from work (kcal) — explanation
Estimated active calories from the measured positive oar work represented by the recording. The calculation uses the measured work before display smoothing and an assumed net efficiency.
Calories from work (kcal) = W / (4184 × η)
W is the represented measured positive work in joules, and η is the configured net efficiency. The current default is 20% (η = 0.20), an assumption rather than a measurement of your personal efficiency.
Calibrated oar work and a valid efficiency are required. Missing work remains unavailable.
Calories from heart rate (kcal) — explanation
Estimated active calories from heart-rate reserve, bodyweight and a supplied VO₂max. For each supported interval:
r = clamp((HR − resting HR) / (maximum HR − resting HR), 0, 1)
Active calories (kcal) = r × (VO₂max − 3.5) × bodyweight (kg) / 1000 × 5 × duration (minutes)
Requires recorded heart rate, duration, bodyweight, VO₂max and configured resting and maximum heart rates. The current app defaults to 65 bpm resting and 170 bpm maximum; enter your personal values. Maximum heart rate must exceed resting heart rate; VO₂max must exceed 3.5 mL/kg/min. Missing recorded heart rate, bodyweight, VO₂max or supported duration leaves the estimate unavailable.
Heart-rate reserve approximates oxygen-uptake reserve. VO₂max is in mL/kg/min; 3.5 mL/kg/min is an assumed resting oxygen uptake, and 5 kcal per litre of oxygen is an approximate energy conversion. Subtracting the resting oxygen level makes this an active-energy estimate.
Planned additions
Mechanical work (kcal) — explanation
Planned for iOS.
Measured mechanical work expressed in kilocalories. This describes mechanical output at the oar, not calories used by the body.
Mechanical work (kcal) = measured work (J) / 4184
Requires calibrated measured work. No metabolic-efficiency assumption is applied to this unit conversion.
Calories from HR profile (kcal) — explanation
Planned for iOS.
A fallback calorie estimate when VO₂max is unavailable, using the general Keytel exercise regression with recorded heart rate, age, bodyweight and sex. Duration converts the estimated energy rate into kilocalories.
This is a general exercise estimate with limited rowing-specific validation. It estimates gross energy during exercise. Comparison with active calories requires a separate subtraction for resting energy; the exercise equation must not be used to estimate energy at rest.
Combined calories (kcal) — explanation
Planned for iOS.
A proposed personalized estimate using measured oar work, recorded heart rate and body-profile information, including bodyweight.
The model needs calibration and rowing-specific validation. It must account for heart-rate lag and the effects of heat and fatigue on heart rate.
The proposed method combines information from these inputs without adding two complete calorie estimates together.
LOAD · MOVEMENT · EFFORT
Rowing physics
Shaft bend describes loading. The force, its lever arm and the oar’s rotation determine how that loading becomes work and power.
Load and movement
At the catch, the shaft can bend before the oar has swept through much angle. There is load, but little sweep work has accumulated. Work increases as that load moves through the drive.
A short, sharp peak and a longer, steadier pull can reach the same maximum load while producing different amounts of work. Holding the oar under load without further sweep adds no sweep work, although shaft bending can store elastic energy.
Bend, moment and force
Force applied through a lever produces a turning effect, or moment, about the pin. Only the component of force perpendicular to the lever contributes to that turning effect.
Moment (N·m) = perpendicular handle force (N) × pin-to-hand distance (m)
Handle force (N) = moment (N·m) / pin-to-hand distance (m)
For example, 300 N·m through a 1.0 m lever corresponds to 300 N of perpendicular force. Through a 1.2 m lever, the same moment corresponds to 250 N.
Shaft stiffness
The shaft bends under load. Its stiffness, together with the positions where that bend is measured, determines the relationship between bend angle and moment. A calibrated Moment/Bend Factor expresses that relationship.
Moment (N·m) = Moment/Bend Factor (N·m/°) × bend (°)
A stiffer shaft requires more moment to produce the same bend angle.
Work and power
Work adds up the moment carried through each part of the drive. The sweep angle in this calculation is in radians.
Drive work (J) = ∫ moment (N·m) × dθ (radians)
Power (W) = positive drive work (J) / full stroke-cycle time (s)
The full stroke cycle includes drive and recovery. Work depends on both the load and the angle through which it acts; power also accounts for the time between catches.
The relationship between this effort and boat speed also depends on hull resistance, wind, current and crew movement.
FROM RECORDING TO UNDERSTANDING
Cloud Analysis
Bring the signals from your row into one interactive workout report. See the effort, compare the strokes and connect the curves to the movement.
RECORDING
Your row, kept together
Oar data, phone motion, GPS and heart rate stay connected to the settings captured with the workout.
ANALYSIS
Detail at every scale
Stroke detection, calibrated effort, motion curves, pieces and groups turn recorded signals into useful comparisons.
REPORT
A workout you can explore
Timelines, curves, summaries, maps and replay offer different views of the same session.
BUILT AROUND YOUR WORKOUT
Review it. Compare it. Keep it.
From iPhone or Android
Analysis supports the app’s workout recordings and the supported Android oar and phone recordings.
Settings with context
The recorded oar setup stays with the workout. Analysis settings can be revised when the original recording is available.
A view that carries forward
Reusable report setups keep preferred plots, scales, map controls and replay views ready for another row.
Results beyond the browser
Downloadable reports, data exports and plot images make it easy to keep and review the results.
SEE THE RESULT
Explore an example workout.
See the report’s actual controls, stroke data, curves and replay.
YOUR WORKOUT, IN VIEW
Explore the report.
See how effort, oar movement and boat motion change through your row. Move from the whole session to the detail of a stroke.
See the whole row
Metrics over time and the GPS route reveal changing effort, pace and the shape of the session.
Look inside a stroke
Loading and motion curves show how the drive develops and how the oar and boat move through the cycle.
Compare your efforts
Pieces and selected strokes bring repeated efforts together, making changes in timing and stroke shape easier to see.
Replay the movement
A synchronized boat-and-oar model connects the curves to the motion behind them, using the recorded inputs and geometry.
INTERACTIVE EXAMPLE
A real workout to explore.
The example below contains the workout’s plots, recorded values and interactive controls. Open the full report for more room.
REPORT SECTIONS
Find your way around
| Section | What you can see |
|---|---|
| Boat & Oar Motion curves | Stroke curves with the matching boat-and-oar replay. |
| Session Overview | Metrics across the workout and the GPS route, with selections for closer comparison. |
| Piece Summaries | Continuous rowing efforts, their duration and rest, and selected summary measurements. |
| All Strokes | Individual stroke values, selectable columns and data exports. |
Your display preferences can travel to another workout as a saved setup. CSV exports, plot images and downloadable reports keep the results useful after the review.
Help with comparisons, controls, saved views and downloads →
Pricing
Oar kits, iPhone subscriptions, Cloud Analysis and plans for your team.
Oar kits
One oar kitSculling or sweep
Regular price$429
Sale price$349
Two oar kitSculling or sweep
Regular price$749
Sale price$649
30-day satisfaction guarantee · 5-year full replacement warranty
App & Cloud Analysis
iOS subscription
Essentials Annual$85 / year
Gold LifetimeAll future features included.$379
Cloud Analysis
Individual Annual$45 / year
Gold Lifetime$200
Team pricing
24 rowers
$6,000 / year
48 rowers
$11,000 / year
72 rowers
$16,000 / year
Coming soon
- RitmoForceCurve Android app
- Coach’s overlay cloud processing
- Coach’s live metrics viewer
Help
Set up your equipment, record a workout and explore your results.
Oar kit
- Assembly & mounting
Fit the housings and straps, then position the sensors on the oar.
- Sensor direction
Check the orientation of each sensor before alignment.
- Kit video
Watch the mounting demonstration.
- Kit instructions PDF ↗
Keep a copy of the assembly and setup instructions.
iPhone app
- Setup & recording guide
From the first connection to a saved workout.
- Connect your sensors
Choose a saved oar or set up a new one.
- Align & record
Follow the alignment movements and prepare to row.
- Rowing views
Choose the metric tiles and curves shown while you row.
- Workout & Auto Piece Timer settings
Set up recording, smoothing and piece detection.
- Share views, settings & oars
Save, share and import your setup.
Oar setup & calibration
- Oar settings & calibration
Understand the dimensions and stiffness used for your oar.
- Calibrate with a known weight
Measure the relationship between load and shaft bend.
- Dimensions & sensor positions
Enter and check the measurements for your setup.
- Manage oars & collections
Organize saved oars and calibration records.
Workout reports
- Upload & analyze a workout
Prepare a recording, review its settings and run the analysis.
- Report controls
Compare strokes, work with plots and maps, save views and export results.
- Boat motion & replay
Mount the phone and understand the motion and replay references.
Android recording
- Oar sensors & alignment
Record the oar sensors with WitMotion.
- Phone motion & GPS
Add a matching phone recording for the workout report.
Need a hand? Contact RitmoForceCurve →
Oar Kit · Assembly & Mounting
Assemble your oar kit.
Assemble each sensor in its housing, secure both mounts to the oar, then use the guided motions to align them. The same kit works with iOS and Android recording.
Parts for each sensor
Lay out the parts below. Repeat the same assembly for your second sensor.
- A Sensor
- B Housing
- C Two side clips
- D Flexible ring
- E Curved saddle
- F Strap
The curved saddle snaps flush into the matching curve at the back of the housing, then rests against the oar. The drawings below show how the parts engage.
1Fit the two clips
Start with the empty black housing. Hook the retaining flange of one yellow clip over the matching housing edge, then press the clip fully home. Fit the second clip on the opposite side, with its flange toward the housing.
Check that both clips are seated and their long strap slots are unobstructed.
2Fit the ring and sensor
Stretch the flexible ring around the outside edge of the sensor. Keep it even around the sensor rather than twisted or bunched at a corner.
Insert the sensor through the open back of the housing. Press it in evenly so the button and logo face remain visible through the front opening. Check that the ring stays seated as the sensor goes in.
3Add the curved saddle
The saddle goes on the curved back of the housing, between the sensor and the oar. The housing and saddle have matching curves, so they nest flush together. The concave outer face rests against the shaft.
Engage one edge lip, then gently flex the opposite edge until it snaps into place. Check that both lips are engaged, the saddle sits flush with no gap, and the sensor remains seated.
4Strap it to the oar
Place the saddle against the shaft and wrap the strap around the oar. At each yellow clip, feed the strap through the slot from the inside (the oar side) to the outside. Fold each end back onto the strap on that same side and press it firmly onto itself.
The strap has hooks and loops together on one face; the other face is smooth. Keep the smooth back against the oar, then fold each end back without twisting so the two fastening faces meet.
The mount should stay put when you gently try to slide or rotate it. Check it again after feathering and squaring the oar.
Position and direction
- Place one sensor between the handle and the oar button, and the other on the blade side of the button. Keep mounts clear of the oarlock and your hands.
- Orient both sensors along the shaft with the offset sensor button toward the blade. That is the sensor’s −Y direction. The sensor’s +Y direction points toward the handle. With the oar held vertically, blade down, +Y points upward. Keep the button face visible.
- Use the actual sensor positions in your oar details and stiffness setup. Moving a sensor changes the setup.
Next · Motion Alignment
Align with a few deliberate movements.
With both mounts secure, record the still, feather/square and sweep movements. The app or Cloud Analysis uses them to learn how the sensors sit on this oar.
Use this motion alignment after mounting or repositioning a sensor. Oar stiffness calibration is a separate step that sets the Moment/Bend Factor used for moment, work and power.
Before the first workout
Confirm the active oar name, side, sensor identities and sensor positions. Save the motion alignment and the stiffness calibration for that setup, then make a short recording to check both sensors. Repeat alignment and review the stiffness setup whenever you move a sensor.
A phone used for boat motion needs a secure hull mount. Follow the iOS recording guide or Android phone-motion guide for the data to record.
Oar Kit · Sensor Direction
Place both sensor buttons toward the blade.
Use the offset button to tell which way the sensor should face along the shaft. Then let the motion alignment establish the sensor reference for your oar.
Sensor Y-axis direction
The round button is offset within the housing opening. Fit the sensor so that this button sits closer to the blade end of the oar.
- Both sensors face the same way along the shaft. Sensor +Y points toward the handle; −Y points toward the blade. With the oar held upright, blade down, +Y points upward toward the handle. The offset button is on the −Y, blade-facing side.
- The button and sensor face remain visible through the housing.
- The saddle sits against the oar and the strap prevents the mount from rotating or sliding.
Repeat alignment if either sensor is removed, turns in its mount, or moves to a different position.
Finish with motion alignment
The mounting check gets the sensors facing the right way. The alignment recording uses deliberate oar movements to account for the remaining mounting angles and resting sensor offsets.
Choose the instructions for your phone below. Each guide takes you from connection and alignment through recording and upload.
Sensor direction and motion alignment establish the measurement reference. Stiffness calibration separately sets the conversion from bend to moment, work and power. Check both after changing the sensor positions.
Oar kit · setup reference
Oar Kit Videos
Setup videos for mounting and using the RitmoForceCurve oar sensors.
How to mount sensors on the oar
Step-by-step overview of mounting the sensors and connecting them for use on the water.
Open videoFollow the current written steps
Use the video as a mounting overview and the illustrated guide for the current assembly sequence. Both offset sensor buttons face the blade; sensor +Y points toward the handle. Finish with motion alignment and the stiffness calibration for your oar.
IPHONE HELP
Set up. Row. Review.
The complete iPhone workflow, with detailed guides for the oar, recording and saved workouts. Use the question marks in the app for explanations beside individual controls.
IPHONE SETUP & HELP
Find the guide you need.
Follow the setup in order for a new oar, or return to a guide whenever the equipment or settings change.
Connect & prepare
Set up the oar
Make it your view
RECORDING GUIDE
From the first connection to a saved workout.
Use the latest iOS beta. Start with these steps and open the linked guides for more detail.
Choose and connect the oar
Turn on the sensors and open Connect Oar. Choose a saved name, then tap Connect. Use Scan oar label if the oar has a QR label; check that its saved setup matches the physical oar and sensor positions.
For a new oar, choose Set up a new oar, connect its two sensors, enter the name, side and type, then tap Save and connect. Enable Connect automatically next time for the selected name if you want it remembered for the next app launch. Confirm that the expected sensors are connected before starting.
Manage Oars includes saved oars, named pairs and separate managed copies. Choosing a record to inspect does not change which oar is connected for rowing. Check whether you are editing the saved oar or an independent managed copy.
Align the sensors and check the scale
Open Oar Settings → Align Sensors. Record Bias, Feather and square, Feathered level sweep and Square level sweep, then calculate and save the alignment. Repeat after moving, rotating or replacing a sensor.
After the alignment is saved, the optional Squared float captures a water reference. Square the blade, float it on the water with the boat level, hold steady for 12 seconds and tap Save to Oar Settings after an accepted capture. This reference does not change the alignment or bias.
Check the active Moment/Bend Factor (MBF, N·m/°). Use a measured stiffness calibration, a suitable existing Cperm with the current dimensions, or an explicitly chosen manual MBF estimate. Bend shape and timing come from the aligned sensors; calibrated moment, work and power need the correct scale.
Saving a new measured stiffness calibration selects its Cperm and clears manual MBF and manual Cperm overrides. Enter the oar dimensions and sensor positions even when using a manual factor; the recording retains them for analysis.
Guided sensor alignment → · Stiffness, dimensions and overrides →
Mount the phone and record the workout
Secure the iPhone to the boat so it moves with the hull. Keep it fixed throughout the session. Allow Bluetooth, motion and location access when requested; phone motion and GPS provide the boat-motion and speed inputs.
Review Workout Settings and the Auto Piece Timer. In Rowing Views, choose the views you want to use, then tap Start Rowing on Home. Record through the work and recovery intervals. Tap End Row when the whole workout is finished.
The app saves the recording and finishes its analysis. Home and workout history show the progress; history may display Finishing analysis — you can start another row while the workout is being prepared. Wait for it to finish before opening that workout’s complete results. Return to the app if processing or a pending upload needs to resume.
In Rowing Views → Available Metrics & Curves, Core choices start selected. Add your selected numbers and curves to a view under Create & Edit Views, then activate it in Active Rowing Views. A missing input leaves the dependent measurement unavailable.
Upload the workout
- Open Home → Cloud Analysis and sign in.
- Choose Analyze latest for the most recent workout, or Choose a workout to select another recording.
- Review its recorded oar setup, analysis inputs and included data. Use Upload Saved Results for supported saved results, or Upload and Run Analysis for raw-data analysis. If that recording already has a server job, the new-upload action can read Upload Raw Data Again as New Analysis.
- Open the completed report, download it, or use Change Settings and Re-run when the original server files remain available.
For automatic upload, enable Upload after each workout. Upload waits for the workout to finish saving and processing. Pending uploads retry while the app is open and when you return. Review the upload status before assuming the report is ready.
After upload, the recording uses the shared Cloud Analysis and report workflow.
Review the saved workout
Open the saved workout in history to browse stroke metrics, pieces and groups, and use the available CSV exports. Pieces are continuous work intervals; groups collect similar strokes from across the workout.
Recorded curve views let you browse individual strokes and compare selections. Time views include a quarter-cycle before and after the selected cycle when neighboring data exist. Vertical ranges stay consistent while browsing, and supported curves can show a variability band when enough strokes contribute.
The cloud report adds the session overview, map, animation and report-view presets. Live values can change after a stroke finishes or the workout is processed with its complete recording.
Understand what the recording keeps
The workout saves the available oar motion, phone motion, GPS and heart-rate data, together with the oar dimensions, sensor positions, alignment, stiffness calibration and applied factor. Enter the dimensions even when using a manual factor.
Cloud Analysis shows this snapshot under Recorded oar settings. Changing the active oar later leaves an earlier workout’s setup intact. Reprocessing older workouts requires their original recordings; a saved summary cannot supply missing sensor data.
Connecting Oar Sensors
Choose the oar you are using, connect its saved sensors, and confirm the oar name and connection status before starting your session.
Open Connect Oar, choose a saved name and tap Connect. Use Scan oar label to import a labeled oar, or Set up a new oar for a new sensor pair. Manage Oars includes saved oars and independent managed copies; opening a record does not change the rowing connection. The reference screenshots below show an earlier beta; follow the current control names in these steps.
Set up a new oar away from other sensors if possible. Save the correct sensors with a clear oar name. Automatic connection can then find that saved setup on future rows, including at a busy dock.
Step 1
Power the sensors and choose your oar
- Turn on the sensors mounted on the oar.
- Open RitmoForceCurve and tap Connect Oar.
- Choose the saved oar under Oars to connect, or use Scan oar label if a label is attached. Check the name, side and setup.
- Tap Connect beside the selected name. For a new oar, use Set up a new oar to create its record first.
A saved oar keeps the setup tied to the correct sensor pair. Found means detected nearby; Connected means fresh readings are arriving. Wait for the expected sensors to connect before starting.
Step 2
Choose automatic connection for next time
- Select the saved oar you intend to use.
- Enable Connect automatically next time for that name if you want it remembered for the next app launch.
- Tap Connect to connect now, then allow a few seconds for the powered sensors nearby to connect.
- If the app keeps searching, confirm the oar selection and check that another phone or app is not using the sensors.
The automatic-connection choice is saved separately from the Connect action. The reference screenshots use the earlier label Autoconnect.
Step 3
Set up a new sensor pair
- Choose Set up a new oar and let the app find nearby unnamed sensors.
- Select and connect the two sensors mounted on your oar.
- Enter a recognizable oar name, its side and type.
- Tap Save and connect to associate the sensors with that oar.
WitMotion names can look alike. If several pairs appear, move away from other sensors or identify your pair before selecting it. You do not need to infer shaft-versus-sleeve position from the Bluetooth name; follow the setup and alignment workflow.
Step 4
Keep the sensors associated with the oar
- Confirm that the expected sensors are connected to the selected oar.
- Enable Connect automatically next time for that name if desired.
- Finish the setup and return to Home.
Switch the active oar in Connect Oar. Review its details and alignment in Oar Settings. Check the selected name before recording.
If needed
Resolve an incorrect selection
- Stop and check which saved oar is selected.
- Disable automatic connection for an incorrect saved selection while you correct it.
- Disconnect the incorrect selection, then choose the right saved oar. If its sensor assignment is wrong, correct the oar’s saved sensor setup before connecting.
- Save the corrected setup and enable Connect automatically next time for the intended name.
Do this away from other active sensors if possible. Closing another app or disconnecting another phone may be necessary before the sensor becomes available.
Ready
Check the setup before rowing
- Confirm the correct oar name and all expected sensor connections on Home.
- Open Oar Settings and review Active Oar details: side, type, dimensions, sensor positions, alignment and active calibration factor.
- If a sensor has moved, repeat motion alignment.
- Secure the iPhone to the boat, check motion/location permissions, choose your rowing view and tap Start Rowing.
The alignment series has four required movements. Save the alignment before using the optional Squared float to capture a separate water reference; save an accepted float to Oar Settings. Confirm the active Moment/Bend Factor and dimensions before relying on calibrated loading.
Troubleshooting
Only one sensor connects:
Check its power, move the phone closer and retry. Power-cycle the missing sensor if needed.
Check its power, move the phone closer and retry. Power-cycle the missing sensor if needed.
Other sensors are nearby:
Confirm your saved oar and sensor pair. Set up new sensors away from other active pairs where possible.
Confirm your saved oar and sensor pair. Set up new sensors away from other active pairs where possible.
A saved name is missing:
Names with no nearby sensors found are hidden. Check sensor power and proximity, then reopen the choice list.
Names with no nearby sensors found are hidden. Check sensor power and proximity, then reopen the choice list.
Another phone or app was connected:
Disconnect there or close that app, then try connecting in RitmoForceCurve again.
Disconnect there or close that app, then try connecting in RitmoForceCurve again.
Set up a named pair
Save each physical oar with its own two sensors first. In Connect Oar, choose Create a sculling pair or two sweep oar pair, select the saved oars, enter a pair name and tap Save and connect. The pair needs four distinct sensors; each oar keeps its alignment and calibration.
A sculling pair uses one port and one starboard sculling oar. A sweep pair uses two sweep oars, which may be on the same side. Confirm all expected connections before rowing. The app offers a choice to use the connected oar or keep looking if a pair is only partly connected after five seconds.
Align both oars becomes available when the pair is connected. Perform the guided movements together; the app processes each oar independently. Alignment instructions →
Oar settings & calibration iOS sensor alignment Record and upload the workout
IPHONE HELP · OAR SETUP
Align your oar sensors.
Four required movements establish the sensor reference. An optional squared float can then save a water reference with the oar.
Before you start
- Choose the correct saved oar in Connect Oar and connect its sensors.
- Check Port/Starboard, Scull/Sweep and mounting positions in Oar Settings.
- Open Align Sensors for that oar. Use the app’s prompts to start and finish each recording.
Keep the mounts secure. Moving recordings do not need a still pause at either end. Keep the blade clear of the water during the level sweeps.
The four alignment movements
Bias
Keep the blade feathered and the oar completely still for 10 seconds. Rest it on a stable support if possible.
Feather and square
Keep the shaft pointing in one direction. Feather and square the blade 5–6 times, without sweeping or lifting the oar.
Feathered level sweep
Keep the blade feathered and the shaft approximately level. Sweep back and forth through at least 90° for 5–6 repetitions.
Square level sweep
Keep the blade square and the shaft approximately level. Sweep back and forth through at least 90° for 5–6 repetitions.
Calculate the alignment after all four recordings are complete, review the result and save it to the intended oar. Recording a replacement movement makes the previous fit out of date; calculate and save again before using that replacement.
When Align both oars is offered for a connected saved pair, perform the guided movements together. Each oar keeps its own alignment. Capture any squared-float reference one oar at a time after saving the alignments.
Optional squared float
- Save the alignment from the four movements first.
- Square the blade and let it float on the water. Keep the boat level and the oar steady.
- Check Outboard, pin to blade tip. If you have separately measured Shaft-axis tip below water, enable that entry and enter the measurement in the displayed units. Otherwise leave it off.
- Confirm Blade squared and floating; boat level, then tap Start 12-second float. Remain steady for the capture.
- After the capture is accepted, tap Save to Oar Settings.
The float saves a reference without changing the sensor alignment or bias. Floating the blade alone does not establish an absolute water depth; the optional measured depth supplies that extra information. The saved reference travels with the oar and its workout.
What to save and when to repeat
Check that the saved alignment belongs to the physical oar and its sensor pair. Repeat alignment when a sensor moves, rotates or is replaced. A matching QR label can supply saved alignment, but verify that its mounts and sensor pair still match.
The squared-float reference is retained when alignment changes. Recheck it after the oar or boat setup changes. If a separately measured manual waterline is entered in Workout Settings, that value takes priority until cleared.
Alignment establishes the sensors’ common reference. Stiffness calibration supplies the scale for moment, work and power.
Keep recording and analysis together
The recording saves the alignment, oar settings and available float reference used for that workout. Re-analysis uses that saved setup, even if another oar is selected later.
IPHONE · ROWING VIEWS
Make the display your own.
Choose clear numbers and curves for the purpose of your row. Keep the explanations close with the app’s question-mark help.
Build and activate a view
- Open Rowing Views → Create & Edit Views.
- Choose a template such as Stroke Technique, Drive Focus or Metric Grid.
- Name the view, tap its metric slots and choose the values to show.
- For a plot view, choose the curves and check their units.
- Save it, then select it under Active Rowing Views. Arrange the active views in the order you want during the session.
Choose a metric grid for large numbers, a plot view for stroke shape, or a mixed layout for both. Available data depends on the connected sensors and recording options. Set up and activate your views before starting the row.
Choose the available measurements
Open Rowing Views → Available Metrics & Curves. Core choices start selected; Advanced/Experimental starts off. Measurements are grouped under Oar, Boat, GPS, Time and Body. Select the measurements you want available, then add them to the slots or plots in your rowing view.
Tap the ? beside an item to read what it measures and which inputs it needs. Changes to available choices apply to the next row or replay.
A dash means the required data are unavailable. Keep the phone fixed to the hull for boat motion, record GPS for ground speed, and connect a heart-rate source for heart rate.
Choose the curves you need
Start with the bend / moment / force curve and oar speed to follow loading through the drive. Add other oar or boat curves when they help answer your question. Check the question-mark explanation for the units, calibration and recording inputs.
Use supporting metric tiles for rate, piece time, distance or pace. Keep each screen focused enough to read at a glance.
Choose a readable plot
- Horizontal axis: Time shows how the motion unfolds; Sweep angle shows measured travel from catch, starting at 0° with an adjustable range. Recovery follows the recorded motion back along that axis.
- Displayed portion: Auto uses the drive portion when every selected curve is a drive curve. Drive portion ends at full feathering when that transition is available; Full stroke includes recovery.
- Curve appearance: White or color styles distinguish the traces. Read the legend for the line style and use the labeled axes for units.
- Compare previous stroke: adds a faint trace of the preceding stroke.
- Show variability: adds a shaded ±1 standard deviation band to supported recorded curves where at least two strokes contribute.
Load and oar speed can share a plot with separate labeled axes. Bend scales to 1.3 times its supported peak, with a minimum upper limit of 0.5°. Missing inputs leave gaps.
Choose After drive separately for eligible load curves and drive measurements in Available Metrics & Curves. These can update when the drive finishes; yellow borders identify that choice. Power and other cycle-dependent measurements wait for the completed cycle.
Review recorded curves
Browse individual strokes and compare recorded selections after the row. Time views cover the selected stroke cycle plus a quarter-cycle on either side when neighboring samples are available. Vertical ranges stay consistent as you browse, and missing neighbors leave gaps.
Horizontal sweep can join smoothly to the next catch during the final half of recovery. This changes only the displayed join; the recorded motion, drive metrics, force and work stay unchanged.
Save and share useful layouts
A shared view carries the layout and selections. The receiving phone still needs the relevant sensors, recorded inputs and compatible app build.
Workout & Auto Piece Timer settings
Choose the live piece-detection settings before you row. The workout saves the settings used for that session.
Auto Piece Timer
The Auto Piece Timer (APT) identifies continuous work intervals. In Workout Settings, choose the trigger and thresholds for your session.
| Control | Meaning |
|---|---|
| APT Trigger | Rate uses the stroke-rate threshold; Power uses power; Both requires both; Either accepts either. |
| Rate / Power Threshold | The effort required to qualify. Power-based detection depends on the active oar calibration. |
| Min Distance | Filters very short pieces from the summary. |
| Auto Piece Time Cutoff | How long inactivity may continue before the piece ends. Repeated non-qualifying strokes can also end it. |
| Piece Rounding | Choose distance or time and its rounding increment. |
Detection needs confirming strokes. A piece’s final endpoint may move back to its last qualifying portion once rowing falls below the trigger or stops.
Other settings worth checking
- Boat Class identifies the boat in the workout.
- Speed Cutoff filters inactive periods in applicable summaries.
- Groups collect similar strokes from anywhere in the session; pieces remain continuous intervals. Adjust group count, rate separation and metric weights when needed.
- Smooth Stroke Metrics smooths supported metrics while responding to changes in effort.
- Include Twist and Include Oar Depth enable those optional calculations before recording.
- Curve display chooses when the stroke curve is shown; recording and completed metrics continue in every mode.
Use the ? beside a setting for its explanation. Choose the measurements for your display in Rowing Views → Available Metrics & Curves; the metric catalog explains what each core item measures.
Oar settings and water reference
Side, type and Moment/Bend Factor come from the selected oar. Check the source and any override in Oar Settings. The recording captures the applied scale and saved dimensions.
After saving sensor alignment, you can capture an optional 12-second Squared float and save it to Oar Settings. This records a separate water reference; a measured shaft-axis tip depth is optional and must be entered if known. A float without that measurement does not establish absolute water depth.
Where a manual waterline below pin (cm) is entered, measure vertically from pin to water surface with the boat level; positive means below the pin. Manual entry takes priority until cleared. Check the reference again after rigging or boat loading changes.
Changing settings for future workouts does not alter a session already recording.
Calorie estimates
Open Workout Settings → Calorie estimates. For work-based calories, review Work efficiency and Work represented against the recorded setup. The default 20% efficiency is an assumption, not a measurement of your personal efficiency.
For heart-rate calories, enter Body mass (kg), Resting heart rate, Maximum heart rate and VO₂max (mL/kg/min), and record heart rate during the workout. The app starts with 65 bpm resting and 170 bpm maximum; replace these defaults with your personal values. Missing recorded heart rate, body mass, VO₂max or supported duration leaves this estimate unavailable. The current work and heart-rate estimates are separate Body choices under Advanced.
The metric reference explains these methods and the planned mechanical-energy, HR-profile and combined estimates.
Review or re-run later
After End Row, let the workout finish saving and processing. Home and history show its progress; you can start another row while the earlier workout finishes analysis. Open Cloud Analysis and choose Analyze latest or Choose a workout. Review the recording’s settings and included data before uploading. To automate the upload, enable Upload after each workout; pending uploads retry while the app is open and when you return.
Use Change Settings and Re-run to rerun detection, grouping or processing while raw files remain available. Use a new upload for a different recording. The finished HTML report’s temporary calibration adjustment updates effort-derived values but keeps its generated pieces and groups fixed.
iPhone setup & helpiOS sensor alignmentOar settings & calibration
Share views, settings and oars
Choose the sharing method for the item you want to move to another phone.
Choose what to share
| Item | Workflow |
|---|---|
| Custom live views and workout settings | Share & Import on Home opens the view/settings share-text tools. |
| Saved or managed oars and collections | Manage Oars provides the corresponding JSON import and share tools. |
| Saved calibration or oar label | Use the calibration export and Print oar labels tools. |
| Cloud report layout | Use the completed report’s view-preset controls. |
| A recorded workout | Upload the workout to Cloud Analysis, then share its report or data exports. |
Share views and workout settings
- On Home, open Share & Import → Share Views / Settings.
- Select the views and whether to include workout settings. Add a naming prefix if useful.
- Tap Generate Share Text, then Share or Copy to Clipboard.
On the other phone, open Share & Import → Import Views / Settings, paste the text and tap Read Import Text. Review the preview and choose whether to import views, settings and make imported views active. Resolve any name conflicts, then tap Import.
Check the resulting screens and thresholds before rowing. A shared layout cannot supply an unconnected sensor or missing recording.
Share oars or a crew collection
- In Manage Oars, use Share oar and calibrations for a single record, Share collection for a collection, or Share managed oars and sensor calibrations for the full managed export.
- Send the JSON file. The recipient saves it to Files.
- On the receiving phone, choose Import managed oars, select the JSON file and review the oars and collections.
- Tap Import copies.
Existing oars remain intact. Imported managed copies are not selected for a workout automatically. Review their alignment, stiffness components, history and current dimensions before choosing a rowing setup. Saved-oar collections have their own Saved oar collections — import / share tools.
Check a saved calibration or QR label
Use Print oar labels in the calibration tools to print or share a label PDF. A label can carry oar details and selected calibration/alignment. Use Scan oar label in the connection workflow, then check that the physical shaft, sensor pair and mounting positions match. Calibration CSV exports and label files are distinct from managed-oar JSON and view/settings share text.
Before recording, verify side, type, dimensions, selected calibration and Moment/Bend Factor (N·m/°). An enabled manual MBF takes priority; manual Cperm uses current dimensions. Saving a new measured stiffness calibration selects its Cperm and clears both manual overrides. Re-align after moving or replacing a sensor.
Reuse a report layout
The completed report provides its own view and preset controls for reusing a layout. A preset carries view choices; each report still uses its own recorded data.
Share a workout’s results
A whole-workout upload includes available oar, phone, watch and GPS data, plus the setup captured with that recording. New recordings retain oar acceleration and preserve dimensions even with a manual factor.
The server shows the original snapshot under Recorded oar settings. Analysis overrides do not overwrite it. After processing, download the report ZIP and extract it to open the interactive HTML report. CSV exports provide the available stroke and summary data.
iOS · OAR SETUP
Oar settings and calibration
Save the oar dimensions, align the sensors, and set the scale that converts bend into moment.
Choose the correct oar
For rowing, select the oar in Connect Oar, or scan its oar label. Confirm that the connected sensors belong to it.
In Oar Settings, choose the oar whose details you want to inspect. The screen shows Active Oar details or Selected Oar details; use Edit details to check side, type, model, length, inboard/outboard and S1/S2 positions. You can inspect saved oars while disconnected. Selecting a details or calibration target does not change the rowing connection.
Manage Oars includes saved oars, named pairs and independent managed copies, with their alignment and stiffness histories. Verify which record you are editing. Manage oars guide →
Align the sensors
Open Align Sensors for the selected oar. Record Bias, Feather and square, Feathered level sweep and Square level sweep, then calculate and save the alignment.
The optional Squared float follows saved alignment: square the blade, float it on the water with the boat level, hold steady for 12 seconds and save an accepted capture to Oar Settings. A separately measured depth can accompany this reference.
Calibrate Oar Stiffness
A known-weight calibration measures Cperm, the shaft’s stiffness constant. The app uses Cperm, the selected shaft model and the current oar dimensions/sensor positions to calculate Moment/Bend Factor (MBF).
Alternatively, enter a Cperm already measured for this shaft, or enter a manual MBF estimate. Dimensions alone cannot determine stiffness. Matching PowerSplit to a familiar effort is an estimate, not a measured calibration.
Known-weight calibration → · Dimensions and sensor positions →
Which value takes priority?
| Priority | Source | What happens |
|---|---|---|
| 1 | Manual Moment/Bend Factor | The entered MBF is used directly. Cperm and dimensions do not calculate the factor; saved inboard still determines handle force. |
| 2 | Manual Cperm | The entered stiffness constant and current dimensions calculate MBF. |
| 3 | Measured Cperm | The selected calibration’s stiffness constant and current dimensions calculate MBF. |
These priorities apply while the corresponding manual overrides are enabled. Saving a new measured stiffness calibration selects its measured Cperm and turns off both manual MBF and manual Cperm overrides. Earlier calibration records remain in the history. Changing dimensions alone does not turn off an active direct MBF override. Check the displayed value, source and units before recording.
What the units mean
Moment (N·m) = MBF (N·m/°) × bend (°). Perpendicular handle-tip force (N) is moment divided by inboard length (m). Work adds positive moment × forward sweep in radians. Power divides drive work by the whole stroke cycle, including recovery.
Current iOS and report controls display Moment/Bend Factor, N·m/°. Older files may store FBF in J/degree²; the software converts that legacy value by 180/π. Do not convert a field already displaying N·m/° again.
When the setup changes
For the same shaft and shaft model, Cperm can be reused with unchanged sensor positions and modest changes to length, inboard or outboard. Update saved dimensions and positions whenever they change by more than 0.5 cm. Larger geometry changes, or moving a sensor more than 2 cm, need suitable taper measurements for the shaft model or a new known-weight calibration. Repeat alignment whenever a mount moves or rotates. A different shaft needs a suitable stiffness value.
Keep the dimensions filled in even with a manual MBF. New workouts capture the oar settings, calibration source and applied factor, and show them on the server under Recorded oar settings. Editing an analysis does not overwrite that recording snapshot.
Known-weight oar calibration
Use a known weight to measure shaft stiffness. The app combines that result with the oar dimensions to calculate Moment/Bend Factor.
Prepare the setup
In Oar Settings, select the intended oar, open Calibrate Oar stiffness, then Perform Calibration(s). The screen identifies the target. A calibration for an independent managed copy is saved to that copy.
- Connect both sensors and complete or verify sensor alignment.
- Confirm sensor positions, inboard, outboard, overall length, load/support positions and the shaft profile.
- Enter the known weight in the units shown by the app.
- Place the oar on stable supports and use Tare with no calibration load.
- Apply the weight at the recorded load point and allow readings to settle.
- Review the measured bend and calculated stiffness, then save the result with the correct oar.
Keep the supports, sensor mounts and weight in place during the measurement. Follow the setup diagram and app prompts for the selected oar type.
Use consistent reference points
The seven reference points are Blade Tip, L1 load point, S1 sensor, Button reference face, S2 sensor, L2 support point and Handle End.
Measure longitudinal positions from the blade tip toward the handle. For the illustrated fixture, the required order is Load L1 < Outboard < Support L2. The weight and supports must match the positions entered in the app.
Check the saved result is active
The test measures Cperm. Current dimensions and sensor positions adapt it into Moment/Bend Factor (N·m/°). Check the source shown in the oar’s details after saving.
Saving a new measured calibration selects that Cperm and clears both the manual Cperm and manual Moment/Bend Factor overrides. The older measurements remain available in the calibration history. If you later enable a manual value, check which source is active before recording.
For the same shaft, a measured Cperm is reusable with unchanged sensor positions and modest dimension changes. Update dimensions and positions when they change by more than 0.5 cm. Taper measurements are needed for larger changes or sensor moves greater than 2 cm; otherwise perform a new calibration for that setup. Dimensions alone cannot provide an unknown stiffness constant.
Oar dimensions and sensor positions
Record the geometry of the physical oar, even when you enter Moment/Bend Factor manually.
Edit the correct record
In Oar Settings, select the intended saved oar and open Active Oar details or Selected Oar details → Edit details. Choosing a details target does not change the rowing connection. Check the side, Sculling/Sweep type, model, stiffness source, dimensions and sensor positions. Editing an independent managed copy changes that copy.
- Choose the displayed length unit and enter overall length, inboard and outboard.
- Measure S1 and S2 from the blade tip toward the handle.
- Check the shaft profile and any taper/diameter positions.
- Select measured Cperm or enter a suitable manual Cperm; alternatively choose a direct MBF override.
- Review the Moment/Bend Factor preview and source, then save.
Get sensor locations from photo can help enter positions. Verify its estimates against physical measurements before saving.
Keep the references consistent
| Dimension | Measure |
|---|---|
| S1 and S2 | Blade tip to each sensor position. |
| Outboard | Blade tip to the outboard-facing button reference face. |
| Inboard | The same button reference face to the handle end. |
| Overall length | Blade tip to handle end; inboard + outboard. |
| Taper stations | Distance from blade tip and shaft diameter at that position. |
Use the units displayed by the editor. Stored/uploaded dimensions use meters. Sensor identities and physical positions are separate information: a Bluetooth name does not establish S1 or S2.
Dimensions still matter with an override
A direct MBF override bypasses Cperm and dimensions when calculating the factor. Inboard still converts moment into perpendicular handle-tip force. Dimensions also support the combined oar and boat-motion calculations.
Each new recording saves a snapshot of the dimensions, sensor positions, calibration, manual inputs and applied values. They are sent with the workout and shown under Recorded oar settings during upload and re-analysis. Missing dimensions remain unknown.
Update dimensions and positions whenever they change by more than 0.5 cm. Cperm can be reused for the same shaft with unchanged sensor positions and modest geometry changes. Larger changes, or a sensor move greater than 2 cm, need suitable taper measurements for the shaft model or a new known-weight calibration. Moving or rotating a mount also requires sensor alignment.
Changing dimensions alone leaves an active manual MBF override in place. Saving a new measured stiffness calibration selects measured Cperm and clears both manual Cperm and manual MBF overrides.
Manage oars and collections
Inspect saved oars and pairs, retain calibration history, and organize independent managed copies for a crew or club.
Choose the right record
Open Oar Settings → Manage Oars. The list includes saved oars and named pairs as well as independent managed oars and collections. Opening a detail view does not change the selected rowing connection.
Editing a saved oar updates that saved record. A managed copy has its own details and history. Use Copy to managed oars from a saved oar, or Copy from saved oars or calibrations, when you want an independent managed record.
- Use New oar or copy an existing setup.
- Check the name, side, type, model and intended sensor pair.
- Choose or attach the saved alignment and stiffness calibration.
- Enter current dimensions and review the Moment/Bend Factor preview and its source.
- Use New collection to group oars for a boat, crew or club.
Choose the oars for your next row in Connect Oar.
Measure and maintain an oar
A managed oar’s details offer Create alignment and Perform stiffness calibration. Use Edit to adjust its details or choose saved components. A saved oar’s details use Edit oar details; use the selected oar in Oar Settings for alignment and stiffness measurement.
Current dimensions may differ from those at the original calibration. Reuse Cperm for the same shaft with suitable geometry and shaft-profile information; use a new measurement when the changed setup is not covered. The original alignment and calibration records retain their measurement history.
A manual MBF uses the entered factor directly; a manual Cperm still needs current dimensions. Saving a new measured stiffness calibration selects its Cperm and clears both manual overrides. Check the saved sensor pair, alignment, calibration and active factor before using the setup.
Alignment steps → · Known-weight calibration → · Dimensions and sensor positions →
Share or import a collection
- For an individual record, choose Share oar and calibrations. For a collection, use Share collection. The full export action is Share managed oars and sensor calibrations.
- Send the resulting JSON file using Mail, Messages or AirDrop.
- On the receiving phone, save it to Files.
- In Manage Oars, choose Import managed oars, select the file, review its contents and tap Import copies.
Existing oars are kept. Imported copies are not selected for a workout automatically. Saved-oar sharing includes the chosen setup; an independent managed copy can preserve the fuller alignment and stiffness history.
The Saved oar collections — import / share tools handle saved-oar collections. Check the destination and selected records before importing. Managed-oar JSON, view/settings share text, calibration CSV and printable QR labels have different purposes.
Print and use an oar label
In the calibration tools, choose Print oar labels and use the print or Share PDF action. A label can carry oar details and selected alignment/stiffness values.
Use Scan oar label in the connection workflow. Verify that the label describes the physical shaft, sensors and mounting positions now fitted to the oar.
Before using a shared setup
Check the exact shaft, sensor pair, positions, side, inboard/outboard, selected calibration and active override. A shared record cannot verify the current mounting. Repeat alignment after moving or replacing a sensor.
UPLOAD & ANALYSIS HELP
Upload & analysis help
Upload your recording, review the settings and open a report of your row.
Prepare your recording
iPhone: open Home → Cloud Analysis. Choose Analyze latest for the most recent workout or Choose a workout to select a recording. You can also export the complete workout. Keep its oar recording, phone motion, GPS and saved oar settings together.
Android: select the WitMotion workout TXT and its alignment TXT when needed. Add the matching Sensor Logger ZIP for boat motion and GPS. Keep the original filenames and columns.
Upload and analyze
- Start new upload. Use this before selecting a different recording or rower. It clears the active files and current analysis; saved workouts remain in your history.
- Select the complete workout. Upload its ZIP or supported files from the same session. Confirm the rower and recording.
- Choose settings. Use the settings recorded with the session, a saved set or defaults. If a choice is shown, press Use these settings, then review the editable fields.
- Review the oar and boat setup. Confirm side, oar type, calibration and dimensions. For Android, also confirm the recording timezone and alignment source.
- Press Analyze workout. Open the report when processing finishes. You can change settings after upload; no extra approval checkbox is required.
Each new upload receives a new workout ID, including recordings for the same rower and day. Re-analyze reruns the selected existing workout and keeps its ID. Use it to change processing settings for that recording.
Oar setup and calibration
Mounting alignment puts both sensors into the same oar frame. Stiffness calibration converts oar bend into moment, work and power. Estimated handle force also needs the correct inboard length.
Current iPhone exports carry the oar’s dimensions and calibration, including manually entered values. Review them under Recorded oar settings. Two-oar recordings retain separate settings for each oar. Analysis changes do not overwrite the recorded setup.
For iPhone DAT recordings, the server uses the mounting alignment already applied by the app. Raw Android TXT recordings need a suitable uploaded alignment or a saved alignment for the same unchanged setup. A newly uploaded alignment normally takes priority.
Keep factor names and units together when entering calibration manually. See oar stiffness calibration for the app and server fields.
Review the result
Use Session Overview to see rate, power, pace and your chosen metrics across the row. The GPS map shows the route when position data is available. Piece Summary compares continuous efforts; All Strokes shows individual values.
In Boat & Oar, compare averaged curves or inspect individual strokes with the animation. Select metrics and curves under Oar, Boat, GPS, Time and Body. Core gives a shorter list; Advanced includes Core and is the default.
Phone motion adds boat outputs; GPS and heart rate appear when recorded. A value with missing input remains unavailable. Read the metric reference for definitions and required inputs.
Pieces and groups
Pieces are continuous rowing efforts. Automatic groups collect strokes with similar properties. To make your own comparison, zoom Session Overview and use the visible strokes to create a named group. The group controls sit below the curves.
Compare pieces or groups in the summaries, averaged curves and map. Use individual strokes to see how much the technique varies within the selection.
When to re-analyze
| Change | Where to make it |
|---|---|
| Displayed metrics, curves, scales, zoom, map and replay view | In the open report. Save the arrangement under Setups. |
| Display calibration factor | In the report where offered. This rescales supported load and effort values; it leaves the original detection and grouping in place. |
| Stroke or piece detection, original groups, alignment, boat processing or analytical geometry | Re-analyze on the server. Rerun power-based detection after changing its calibration. |
Keep your report and reuse your view
Download the report ZIP, extract it and open the HTML in a browser with JavaScript enabled. The report contains its plots and data; background maps need internet access. Keep the original workout files for future analysis.
Use Setups → Save new → Download setup to save your plot, map and animation preferences. Open another workout’s report and choose Setups → Import setup to reuse them. See the saved-view guide for what carries over.
Downloaded reports keep the data and controls with which they were generated. Re-analyze the original recording to use newer processing.
REPORT HELP
Report help
Compare parts of your row, inspect individual strokes and replay the boat and oar together.
Find your way around
| Section | Use it for |
|---|---|
| Session Overview | Metrics over time, zooming into an effort, selecting strokes and viewing the GPS route. |
| Boat & Oar | Averaged or individual curves with the matching boat-and-oar animation. |
| Piece Summary | Continuous efforts, their duration, rest and selected summary metrics. |
| All Strokes | Individual stroke values, selectable columns, search and CSV export. |
Open the HTML in a browser with JavaScript enabled. A file preview may show only static content.
Make a comparison
- In Session Overview, choose rate and power. Add GPS pace or heart rate if recorded.
- Zoom the part of the row you want to compare. Use the group controls below the curves to create a named group from the visible strokes.
- Open Boat & Oar → Averaged curves. Select that group and another group or piece.
- Switch to Individual strokes to inspect the strokes behind an average.
Searching the stroke table only filters that table. Create a group when you want a new selection to determine the averages.
Choose metrics and curves
Advanced is the default detail level and includes all Core choices. Choose Core for a shorter list. Choices stay grouped by Oar, Boat, GPS, Time and Body; changing the detail filter preserves your selected plots.
Choose bend, moment or estimated handle force for the load display. GPS speed and GPS pace are separate choices, as are peak moment and peak handle force. Use Show variability to add stroke-to-stroke spread to supported averaged curves.
Boat metrics include set, pitch, heave, distance check, speed check and energy-loss check. See the metric reference for their meanings and inputs.
Read and adjust the curves
- Time or sweep angle: time shows when events occur; sweep angle shows where they occur along the stroke.
- Full-cycle context: the default time view spans 1.5 cycles, including a quarter-cycle before catch and after the next catch. This shows the transitions between recovery and drive.
- Horizontal sweep angle: select it under Oar at Advanced level. It combines the two supported horizontal gyro sweeps. Oar depth angle is also available.
- Scale and position: adjust each curve’s range and vertical position. Use Auto for the relevant visible data, All for a broader range or Fit this stroke for a closer view.
- Hover: read each curve’s value in its own units. The shared time or angle appears at the bottom of the cursor line.
Horizontal sweep joins smoothly through late recovery where the next catch is recorded. This display adjustment preserves drive values and workout metrics. Missing neighbouring data remains a gap.
Curve heights are independently scaled. Use the labels and units when comparing magnitudes.
Arrange and play the animation
Use Layout for side by side, animation above curves, curves above animation, animation only or curves only. Curve and animation views use the same stroke selection.
Click a curve to make the animation follow the pointer. Click again or press Escape to freeze it. Adjust the viewing angle, zoom and water display; use 1× motion exaggeration to judge the size of movement.
For a sequence, open Individual strokes, choose the piece, group or range, and press Play selected strokes with Continue through selected strokes enabled. Turn continuation off to repeat one stroke. Recorded gaps remain gaps.
The standalone combined replay also has a stroke navigator, a fixed-centre cursor option and a Visible strokes control for up to six cycles. Individual context uses retained neighbouring strokes; averaged context repeats the selected average.
The animation is a model built from the available data and geometry. A displayed opposite oar may be mirrored from one recording. Read boat motion and replay for the hull reference, waterline and slip.
Use the GPS map
The map can show a selected group or the strokes visible in Session Overview. Choose a metric to colour the route, then zoom or pan. The track and available pace or speed depend on the GPS recording.
Map backgrounds need internet access. GPS speed is speed over ground, so current can affect it. Gaps in the recording remain gaps.
Save a view and reuse it
- Arrange the plots, metrics, scales, layout, map controls and animation camera as you want them.
- Open Setups, enter a name and choose Save new. Use Update selected to replace an existing setup.
- Choose Make default to open this report with that setup in this browser.
- Choose Download setup to keep the small
.ritmo-setup.jsonfile. - In another workout’s report, choose Setups → Import setup and select the file.
A setup carries the display preferences, including curve choices, summary and table selections, separate average and individual scales, layout, animation camera, zoom and viewing angles. Map display controls carry over; the new workout keeps its own route and map location.
Importing a setup preserves the new workout’s data, oar side and selected strokes. It skips unavailable metrics and tells you what could not be applied. Workout names, recorded samples and sensor alignment are excluded.
Local setups can restore selections within the same workout. Use Back up all to keep a copy of your saved setup collection. Keep the downloaded JSON to use your preferences in another browser or on another device.
Understand averages
Server-generated group and piece curves use the analytical samples. Strokes are compared at matching elapsed times or sweep positions, so the number of contributing strokes can change along a curve.
Groups created in the browser use the individual curves stored in that HTML. Their curves can be less detailed when the report contains reduced samples; their metric summaries use the stored analytical values. Show variability describes differences between strokes.
Distance check, speed check and energy-loss check summaries are the arithmetic mean of valid member-stroke values. They are not summed. Missing values are excluded, rather than counted as zero.
Export and re-analyze
- Summary and averaged-curve CSVs: export the selected comparison.
- All Strokes CSV: export the columns you have chosen.
- Shown-curves CSV: export the selected individual curves and units.
- PNG or JPEG: save the current plot and legend.
- Download animation HTML: keep a standalone replay of selected content.
A report calibration change rescales supported load and effort values while preserving the original detection and grouping. Re-analyze on the server to change processing settings or recalculate an older workout. A downloaded HTML keeps the data and controls of the version that generated it.
BOAT MOTION
Boat motion & replay
See how the hull moves through the stroke and compare that movement with oar effort.
Fix the phone to the boat
Mount the phone rigidly to the hull or a structure that moves with it. Keep it in the same position for the row. A loose phone, pocket or sliding seat also records movement that does not come from the hull.
Keep phone motion, GPS and oar files from the same session together. The analysis aligns their timing so the curves can be compared.
The hull reference
In the cloud report, the default Local gravity reference measures pitch and set relative to a slowly changing neutral plane. It averages gravity directions over neighbouring complete strokes in a 20-second window. This preserves movement within each stroke while removing slow changes in the baseline.
The phone’s mounting angle is accounted for, but its forward direction must match the boat. Enter the known bow direction and phone-to-pin offsets when available; otherwise direction is estimated from the rowing pattern.
The neutral plane is a rowing reference. Slow trim changes are removed along with slow reference drift. Live app values can differ from final analysis near the beginning, end or gaps because live processing has less neighbouring data.
Change the reference under the server’s boat settings, then re-analyze. The Local gravity window can be adjusted from 5–120 seconds. The iPhone app can also use a saved boat-level reference when configured.
Read the motion curves
| Curve | Meaning |
|---|---|
| Forward acceleration · m/s² | Along-boat acceleration after gravity removal. The default filter is 8 Hz. |
| Fused boat speed · m/s | Ground speed combining the GPS reference with faster changes from phone acceleration. |
| Relative boat speed · m/s | Phone-derived speed variation around the stroke-cycle mean. Zero means the cycle mean. |
| Relative boat distance · cm | Forward or backward position relative to steady motion through the cycle, derived from relative speed. |
| Set / roll · ° | Hull roll relative to the neutral plane. Positive is port up. |
| Pitch · ° | Bow-up or bow-down rotation relative to the neutral plane. Positive is bow up. |
| Heave · cm | Estimated rise and fall around the stroke-cycle mean. |
| Turn · ° | Turn from catch or relative to the chosen course. Positive native turn is port/left. |
Choose these under Boat. Advanced includes the Core choices plus pitch, heave and turning. Relative curves describe movement within the stroke; fused speed retains its absolute ground-speed value.
Cycle-based motion estimates limit drift and can remove slower movements. A wave or other movement that does not repeat with the stroke may be represented less well.
Compare stroke metrics
Set range, pitch range and heave excursion describe movement size. Distance check is the full-cycle range of relative boat distance; Speed check is the range of relative boat speed. Both use phone motion.
Energy-loss check uses the complete fused GPS and phone-motion speed cycle. It compares the integral of squared speed with steady travel at the same mean speed. The percentage is a speed-variation index, not a direct measurement of energy lost.
Piece, group and workout summaries average the valid individual values. Compare strokes at similar rate and effort, and look at both the size of a movement and when it occurs.
Boat metric definitions and units →Course and turning
Drive and recovery turn show how the hull rotates during each phase. Use the turning control to compare native hull turn or turn relative to the selected course.
Straight course uses the piece’s endpoint line. Curved course follows a fitted gradual path. Course offset and estimated extra distance require sufficient GPS coverage.
Steering, wind, course bends and unequal oar action can produce similar movements. Compare the route and oar curves before interpreting a turn.
Replay the boat and oar together
Open Boat & Oar, then choose Averaged curves or Individual strokes. The plots and animation follow the same selection.
Use Layout to place curves beside or above the animation, or show either alone. Click a curve to move the animation with the pointer; click again or press Escape to freeze it.
Play a selected sequence to see how the movement repeats. Adjust the camera and zoom, and use 1× motion exaggeration when judging size. Save the view under Setups to reuse it on another workout.
The hull and blade shapes are models driven by the available motion and geometry. A displayed opposite oar may be mirrored from one recording.
Playback, saved views and downloads →Waterline and blade trails
The replay uses a supplied physical waterline reference when available, or an estimated waterline from the model. Waterline offset lets you explore a different position. A saved squared-float reference and a physical waterline height are separate inputs.
Enable Show blade slip trail to see the outer blade trace and a dashed inner trace. The inner trace follows the submerged blade edge nearest the handle. If the shaft enters the water, it follows the wet shaft to the surface.
The trails depend on oar depth, feathering, hull motion and the model’s waterline. They illustrate the assumed geometry; the water texture does not measure current.
Slip
Slip compares modelled oar movement with boat speed. It depends on synchronized data, oar dimensions, angle placement and assumptions about the water.
Average drive slip is a signed longitudinal speed: positive means rearward, and negative values are retained. Missing intervals are excluded. Treat it as an experimental comparison under the stated model assumptions.
Slip speed is different from catch miss, which measures angular travel before sustained load.
Android · WitMotion oar recording
Align & record on Android
Connect both oar sensors in WitMotion. Make one short alignment recording, then a separate recording of your row. Add a Sensor Logger recording if you also want boat motion and GPS.
1. Connect your two sensors
Charge both sensors and mount them securely in their rowing positions. Keep the same oar, sensor pair, mounting positions and strap tension for alignment and rowing.
- Turn on Bluetooth and grant the Bluetooth/location permissions Android requests.
- Connect inside WitMotion. Use the last 3–4 characters of each sensor address to recognise your pair when other sensors are nearby.
- Set both supported oar sensors to 200 Hz and check that both are streaming.
- Open the connection screen. On WitMotion’s Main screen, tap the chain/link icon near the top right.
- Check the product. Use Select Product… if needed, select your model, then go back. The example screens show WT9011DCL-BT50.
- Connect both sensors. On Available Devices, choose Multip and turn on the switch beside each of your sensors.
- Check live data. Return to Main, gently move the oar and check the changing values for both sensors. Swipe between their cards if necessary.
Connection screens
2. Record five alignment blocks
With both sensors connected, tap the red record circle. Keep one continuous recording running through all five blocks below. Keep the blade clear of the water during the moving blocks, then use the water for the final floating-square-blade reference.
Rest still · 10 seconds
Rest the oar on stable supports. Keep both sensors motionless.
Feather and square · 5–6 times
Point the shaft in one direction. Rotate between feathered and square without sweeping or lifting it.
Feathered level sweeps · 5–6 times
Keep the blade feathered and the shaft approximately horizontal. Sweep back and forth through at least 90° without rolling the shaft.
Square level sweeps · 5–6 times
Keep the blade square and the shaft approximately horizontal. Make the same back-and-forth sweeps through at least 90° without feathering.
Floating square blade · 12 seconds
With the oar in its normal rowing position, keep the blade square and let it float naturally at the water surface. Hold the oar still for 12 seconds, without pressing it down, lifting it out or feathering. Record this as the fifth block, after the square level sweeps.
Pause for a few still seconds between blocks. Do one type of movement at a time. Finish with a few still seconds, then stop and save the recording.
Keep this short TXT clearly named as your alignment recording. Start a new recording for the workout.
When to repeat alignment
Repeat it after moving, rotating or removing a sensor, changing the sensor pair, or changing the oar setup. A saved alignment only applies to the setup used to record it.
The initial still block supplies the gyro-bias reference; the first four blocks supply the core mounting alignment. The fifth records the floating-square-blade reference. This final block is still, not a swooping or rotating movement. Keep all five in the same TXT. If a new alignment cannot be fitted, repeat the recording rather than relying on a plausible-looking curve. Review the report’s reference notes before assuming the float has been applied to waterline or blade-depth calculations.
Alignment and stiffness are different
Alignment puts the sensor measurements in the same oar reference. Oar stiffness calibration supplies the scale used for moment, work and power. Review your side, boat type and Moment/Bend Factor before running the report.
3. Record your row separately
- Check both sensors. Confirm both are connected and showing live values before you start.
- Start the workout recording. Tap the red record circle a few seconds before rowing.
- Keep WitMotion in the foreground. Leave it open with both sensors connected throughout the row. Avoid force-closing the app or disconnecting Bluetooth.
- Stop and save. Tap the square stop button, then the folder icon to find the recording.
Before relying on a full workout, make a short test recording and check the exported TXT contains both sensors and the full recording period.
Optional: record phone motion & GPS
A phone fixed rigidly to the hull can record boat motion and position while WitMotion records the oar. Use Sensor Logger in the background and keep WitMotion in the foreground.
The phone guide covers the exact sensors to enable, a short background-recording check, the separate-CSV ZIP export, and matching the recording timezone.
Android phone motion & GPS guide →4. Export your TXT files
- Find the date/time folder. Tap the folder icon on Main and open the folder for the recording.
- Select the TXT. Choose the .txt file. The .wplay files are not the main upload files.
- Check both sensors. The DeviceName column should contain both sensor IDs somewhere in the file. Keep the original timestamps, sensor identity, acceleration, gyro and any other exported columns.
- Share the original file. Use the share icon to save it somewhere you can access from the uploader. Do the same for the alignment recording when needed.
No manual column deletion, splitting or conversion is needed. Keep your original recordings as your own copy.
5. Upload the matching recordings together
Open Cloud Analysis and choose Start new upload. This clears the active recording and settings so the next upload gets its own workout ID.
- First upload or changed setup: select the short alignment TXT and the larger workout TXT together, or put both in one ZIP.
- With phone data: also select the matching Sensor Logger CSV in Zip File export. Keep one phone recording per workout upload.
- Check before running: confirm the recording timezone, Port/Starboard, Scull/Sweep and Moment/Bend Factor in the analysis settings.
Review the settings after upload, then press Analyze workout. With Uploaded alignment first, the alignment TXT you selected takes priority. The account’s saved alignment can be used for later rows with the same unchanged setup when no new alignment is supplied.
Automatic oar-side detection is enabled by default. To set a known side manually, choose it in Oar info and turn off Automatically detect oar side. The resolved side also sets the animation. Repeat alignment when the mounting changes.
Connection and recording troubleshooting
- No sensors: turn them on, bring them close to the phone, refresh the list and check Android Bluetooth/location permissions.
- Only one connects: select Multip and turn on both sensor switches.
- Values stop changing: reconnect and check both sensors before starting a new recording.
- Too many nearby sensors: match the last 3–4 characters of the addresses you noted for your own pair.
- Cannot find a recording: open the date/time folder from WitMotion’s folder icon and share the TXT directly.
Android · optional phone recording
Phone motion & GPS
Record the hull with Sensor Logger while WitMotion records the oar. Upload both recordings together to add boat-motion curves, GPS and the inputs for boat replay.
1. Fix the phone to the boat
Use Sensor Logger by Kelvin Choi on Android. Mount the phone rigidly to the hull or a structure that moves with it, and keep it there for the whole recording. Its mounting angle can be arbitrary, but it must not shift.
A pocket, sliding seat or loose phone also records the rower’s or phone’s movement. That cannot be interpreted as hull motion.
2. Choose the phone sensors
Enable these streams before recording. Keep their original names and units.
| Sensor Logger stream | What it provides | Setting |
|---|---|---|
| Accelerometer | Linear acceleration for boat-motion analysis. | Enable |
| Gyroscope | Rotation of the phone and hull. | Enable |
| Orientation | Phone attitude needed for the default recorded-attitude analysis. Keep the standard quaternion export. | Enable |
| Location | GPS position, speed and route. | Enable |
| Gravity | Gravity direction for the boat reference. | Recommended when available |
| Total Acceleration | Acceleration including gravity, retained for boat-motion processing. | Recommended when available |
Request about 100 Hz for motion, or up to 200 Hz if supported. GPS can keep its own normal update rate, typically around once per second. Actual rates depend on the phone; do not repeat GPS fixes at the motion sampling rate.
3. Check that background recording works
- Allow recording access. Grant the motion, location and background permissions needed by Sensor Logger.
- Make a short trial. Start Sensor Logger, switch to WitMotion and record both sensors for a few minutes.
- Check both exports. Confirm Sensor Logger kept recording while WitMotion was in the foreground and that the two recordings overlap. If Android stopped the logger, review its battery restrictions and background-location settings, then repeat the trial.
4. Record the same workout
Start Sensor Logger shortly before the WitMotion workout recording. Keep WitMotion in the foreground throughout the row, then stop and save both recordings.
Use the phone’s correct date, time and timezone. The apps do not have to start at exactly the same instant. Avoid applying a separate clock correction in only one app.
5. Export separate sensor CSVs in one ZIP
- Choose Export → CSV in Zip File. Keep the separate sensor CSVs and Metadata.csv together, with their original filenames.
- Select the matching files for upload. In Cloud Analysis, choose Start new upload, then select the WitMotion workout TXT and Sensor Logger ZIP together. Include the short alignment TXT when you need a new oar alignment.
- Use one phone recording per workout. Do not mix different phones or multiple Sensor Logger sessions in the same upload.
Choose the separate-CSV ZIP export, not Combined CSV, JSON or SQLite. Combined CSV resamples the sensor streams. The separate files preserve the original motion and GPS timing.
You can also select the extracted CSVs, keeping their filenames, or place the WitMotion TXT beside an extracted Sensor Logger folder in one outer workout ZIP. There is no need to merge rows or convert files.
6. Review the recording timezone
Before running analysis, check Recording timezone matches the location of the row, for example America/Los_Angeles. The server can read this from Sensor Logger’s metadata; an explicitly selected setting takes precedence.
Sensor Logger records absolute timestamps, while WitMotion’s date/time text normally represents local time. A wrong timezone can put the recordings hours apart. Keep Metadata.csv and the original clocks; do not move the first rows into alignment by hand.
If the report has no overlapping phone data, check the timezone and that you selected the matching workout before changing other settings.
Continue in Cloud Analysis
After upload, review the settings and press Analyze workout. Phone motion adds boat curves and replay; location adds the route and GPS speed or pace. A Sensor Logger ZIP accompanies the oar workout TXT. Use Start new upload for another recording, or Re-analyze to change settings for the existing one.
Contact
Questions about RitmoForceCurve or need help with your setup? Email us.
ritmoForceCurve@gmail.comFor instructions on the oar kit, iPhone app and workout reports, visit Help.