Tacking Training

The Tacking Training mode coaches you through a series of upwind tacks and measures how much height you gain or lose on each one. Using GPS data collected before and after every tack, the app calculates your Velocity Made Good (VMG) and compares actual height gained against the height you would have achieved by sailing straight on — giving you objective feedback on tacking technique.

How a training session works

A session is guided by four phases that repeat automatically for every tack:

Pre-tack – After you tap Start, the app gives you time to get up to speed on the upwind course. A countdown runs: "5, 4, 3, 2, 1 — Tack now!" tells you exactly when to execute the tack.
Tacking – The app records GPS data during the tack itself. It automatically detects the tack point from the heading change (a change of more than 40° is required).
Post-tack measurement – For a configurable window after the tack (default 10 seconds), VMG on the new tack is measured.
Feedback – The app announces the result aloud: "Good tack! Gained X metres" or "Lost X metres." After a brief pause it automatically starts the countdown for the next tack.

Height change calculation

For each tack the app computes:

A combined VMG from the pre-tack and post-tack legs, weighted by duration.
The actual height gained, calculated as the straight-line distance between the GPS position at the start of the pre-tack window and at the end of the post-tack window, projected onto the wind direction.
The expected height — what the combined VMG would have produced over the same total time sailing straight toward the wind.
Height change = actual height − expected height. A positive number means you gained height through the tack; a negative number means you lost height.

A 2-second exclusion zone around the tack point is ignored so that the turning manoeuvre itself does not distort the VMG averages.

Wind direction

You can enter the wind direction manually at any time. If no wind direction has been set, the app infers it automatically from the tack geometry — it calculates the bisector of the pre-tack and post-tack bearings and uses that as the wind direction for all subsequent height calculations. The inferred wind direction is displayed and can be overridden manually at any time.

On-screen information

While a session is running the screen shows:

Phase status – current phase and countdown to the next tack.
Live metrics – real-time COG, SOG, and Compass Heading.
Wind direction – current setting with a manual input field.
Average tacking angle – the mean angle through which you have been tacking, averaged across all completed tacks in the session.
Map – satellite view showing your last 30 seconds of GPS track. Completed tack points are marked, and the height change for each tack is labelled directly on the map.
Last tack result – the height change from the most recent tack, displayed prominently.
Total tack count – how many tacks you have completed in the session.

Tack history

Every completed tack is saved as a card in the history list below the main controls. Each card shows:

Tack number and height change (green for positive, red for negative).
Tacking angle (the bearing change from pre-tack to post-tack COG).
A mini map with the pre-tack track in red and the post-tack track in green.
A VMG chart showing speed-toward-wind over time, with a vertical marker at the tack point.

Audio feedback

The countdown and post-tack result are announced aloud via text-to-speech so that you receive feedback without looking at the phone. Tap the mute button on the control card to silence audio at any time.