LogTRC / Propulsion analysis
Prop slip calculator
Compare measured GPS speed with theoretical propeller speed.
Whole active ride
Enter your setup to calculate
—estimated slip %
Speed comparisonkm/h
Measured GPS speed—
Theoretical propeller speed—
Speed difference—km/h · theoretical − GPS
Mechanical RPM—ERPM ÷ pole pairs
Average ERPM—electrical RPM
Slip compares actual speed with pitch-based theoretical speed. It is not a measurement of electrical efficiency.
Whole active ride · original estimate—
Includes acceleration and changing loads.
Steady cruise · time-weighted estimate—
Enter your setup to find stable sections.
How steady cruise is selected
At least 8 seconds with the motor active and GPS speed at least 5 km/h. Speed spread must stay within 2 km/h, ERPM spread within 10% of the window average, and sample gaps within 2.5 seconds. Qualified intervals are weighted by duration. Stable speed alone cannot identify turns or changing water conditions.
Measured vs theoretical speed
The shaded gap shows the speed difference, not electrical energy loss. Estimates assume direct drive and the entered nominal prop pitch.
Enter your setup to build the timeline.
Propeller performance
Compare slip and electrical demand at steady cruising speeds. Hover or tap a graph to link all three cursors, or choose a speed band below.
—
Power versus speed
—Consumption versus speed
—Calculate your setup to see speed-band coverage.
How these curves are calculated
Uses the steady-cruise criteria above. Each 2 km/h band needs at least 5 seconds of qualifying intervals. Slip is calculated from time-weighted GPS and theoretical speeds. Power uses logged watts, falling back to voltage × input current, and needs at least 5 seconds of non-negative power data. Wh/km is integrated electrical energy divided by distance over those same intervals. Empty bands remain gaps. Lower slip does not necessarily mean lower consumption; these curves do not measure thrust or propeller efficiency.
Enter prop pitch and magnet count to estimate slip.