Core metrics & curves

Loaded oar sweep from confirmed load engagement to the end of the loaded drive.

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.

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.

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.

Position along the loaded stroke arc where shaft bend reaches its peak.

Oar sweep from the catch to confirmed load engagement. The shaft may move and bend before sustained loading is established.

Oar sweep from the loaded-drive endpoint to the feather threshold. It is zero when feathering itself defines the loaded-drive endpoint.

Oar sweep from the feather threshold to the finish reversal. It describes movement after feathering begins, separately from the end of the loaded drive.

Recovery time divided by drive time. A value of 2 means recovery lasts twice as long as the drive.

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.

Full oar sweep from catch to finish reversal, including unloaded movement.

Increase in handle rotation speed from load engagement to peak speed, divided by the elapsed time.

Effort-equivalent speed calculated from oar power. Measured speed over the ground is available under GPS.

Highest handle rotation speed during the drive.

Mean oar sweep speed during the drive.

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.

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.

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.

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.

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.

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.

500 m pace calculated from the displayed fused boat speed, including its GPS fallback. A valid positive speed is needed to show a split.

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.

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.

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.

Distance traveled over the ground during the recording, calculated from GPS positions. It follows the ground track, including the effect of current.

Time to travel 500 m at the measured GPS speed. A valid positive speed is needed to show a pace.

Pace for the current detected piece, calculated from its elapsed time and distance.

Distance traveled in the current detected piece.

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.

Strokes per minute measured from successive confirmed catches.

Elapsed workout time.

Elapsed time in the current detected piece.

Identifier used to locate a stroke in the workout data.

Elapsed recording time at the stroke’s catch.

Heart rate over the stroke interval, from a connected heart-rate source.

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.

Research on rowing efficiency ↗

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.

Heart-rate and oxygen-uptake reserve ↗