True Helm

Analysis

Session breakdown · runs offline

Drop a session here

A CSV from the True Helm logbook, or a track from Navionics, Garmin, Vakaros or most other sailing and sports apps (GPX, TCX, VKX). Nothing is uploaded, the file never leaves this browser, and the page works with the network switched off.

Expected CSV format 
timestamp,lat,lon,sog_kn,cog_deg,heading_deg,heel_deg,gps_accuracy_m,compass_quality,time_to_start_s
2026-08-23T10:00:00Z,54.420000,10.160000,5.31,183.4,179.8,19.2,4.1,good,120
2026-08-23T10:00:01Z,54.420021,10.160013,5.28,183.9,180.4,19.8,4.1,good,119
  • One row per second. The maneuver list tolerates a coarser rate, but the detail view measures in rows, so its little track would stretch.
  • Only timestamp, lat and lon are required. A missing sog_kn or cog_deg is derived from the positions.
  • Column order does not matter, and common alternative names such as speed, course or roll are recognised.
  • heel_deg positive means starboard side down.
  • time_to_start_s is the race countdown: positive before the gun, negative after it, empty when none was armed. It puts the gun on the timeline and unlocks the phase buttons above it.
  • The app records everything except heading_deg and compass_quality, which the page reads but does not use. heel_deg is left empty for any stretch where the phone was not upright in its mount, or where the sensor stopped reporting — an empty cell rather than a made-up angle. See the manual.

A GPX or TCX file needs none of this. The track points are read straight out of the file. A watch records position, time and speed, so the course comes from the positions and the heel trace stays empty.

Maneuvers, the polar and the wind estimate work as they do for a logbook CSV.

Track

Starboard tack Port tack Wind

Zoom with the buttons, a pinch, or ctrl and the scroll wheel. Once zoomed in, drag to move around. All frames the whole track, Stretch the piece picked on the timeline — including the one the phase buttons pick for you.

Timeline

+0°

Wind strip: the thick line is the mean wind everything on this page is computed against, fitted to the tacks (filled dots) and gybes (open dots). Click a dot to leave it out, click again to take it back. Dashed where no turn is near enough to say. The thin line is the wind your course implies while beating — where it leaves the thick one, the wind shifted or the boat was steered off.

Drag across the timeline to pick a stretch; on a phone, swiping up or down still scrolls the page. Every tile, table and the polar then use only that stretch, and a bar at the top says so. Click once, or Whole session in that bar, to clear it.

Polar

Maneuvers

Legs

Runs entirely on your machine. No connection, no account, no upload.