Upwind angles and VMG in a dinghy: pinch or foot?
How to find your best upwind angle with VMG and your own polar chart: why pointing higher isn't always faster, how wind strength changes the answer, a three-leg test, and what can mislead you.
By the Waterspeed team
The best upwind angle is the one that gives the highest VMG, not the highest boat speed or the tightest angle. In a dinghy that angle changes with wind strength and waves, so the way to find it is to measure: sail upwind at slightly different angles, compare VMG, and use your own polar chart to see where speed and angle give the most progress to windward.
Pinching and footing, in numbers
Pointing higher shortens the distance you sail but costs speed; footing off adds speed but adds distance. VMG settles it. Example numbers (illustrative, not a class polar):
| Boat speed | True wind angle | VMG upwind |
|---|---|---|
| 4.0 knots | 40° (pinching) | 3.06 knots |
| 4.5 knots | 45° | 3.18 knots |
| 4.9 knots | 50° | 3.15 knots |
| 5.2 knots | 55° (footing) | 2.98 knots |
Here 45° wins. Over a one-nautical-mile beat, 3.18 instead of 3.06 knots of VMG saves about 44 seconds. More on the formula in What is VMG?
How does wind strength change the answer?
The general patterns coaches teach:
- Light air: foot slightly for speed. A dinghy that slows down stalls, and a stalled boat points worse anyway.
- Medium air: the boat reaches its best upwind speed; this is where you can point highest without losing speed.
- Strong wind: depower and keep the boat flat; pinching slightly can reduce heel, but too much and speed drops fast.
- Waves: foot a little more to keep speed through the chop.
Your own data shows where these switch points are for your boat, weight and rig.
How do I read my own polar chart?
A polar chart plots your speed at each angle to the wind. Waterspeed Ultra builds one from your GPS track and the session’s wind direction:
- Find the peak upwind VMG. It’s typically between 40° and 50° true wind angle; your chart shows where yours is.
- Compare the average line (cyan) with the maximum line (red, dashed). A big gap means you reach that speed but don’t hold it.
- Look for dips: angles where you are slow, usually trim or steering.
- Points below 3 km/h and angles under 35° are filtered out as unreliable.
A three-leg test
- Check the wind direction saved with the session; every angle and VMG depends on it.
- Sail three upwind legs of at least five minutes each (Waterspeed needs five minutes and 50 GPS points to call it a leg): one at your normal angle, one pinching slightly, one footing slightly.
- Keep everything else the same: trim, crew position, the same stretch of water.
- Compare the legs: average VMG, angle and speed. Waterspeed stars your best leg and colours the others against it (green within 10%, orange 10–20%, red beyond).
- Repeat in another wind strength to build your own targets for light, medium and strong wind.
What can mislead you?
- Wind shifts. Waterspeed uses one average wind direction per session; on a shifty day a “great” leg may just have been a lift. Test on steady days.
- Current. GPS measures speed over ground, so tide changes VMG without changing how well you sailed.
- Too little data. Waterspeed’s confidence check flags angles with too few points; trust angles you sailed for minutes, not seconds.
Is pinching ever right?
Yes, briefly: to hold a lane off the start, to make a mark, or to depower in a gust. As a default it usually costs VMG.
Related: Race analysis with GPS replay, Sailing performance metrics.
