Your tacks are losing you more speed than you think

Every tack and gybe costs speed, and the loss is usually bigger than it feels, because the time spent rebuilding speed afterwards hides how much went in the turn. Waterspeed measures it: it detects each tack and gybe from your GPS track and shows entry speed, exit speed and how much you kept, for sailing, windsurfing and wingfoiling.

You already feel it when you come out of a tack slower than you went in. The data tells you how much slower, on which turns, and whether the problem is the entry or the exit.

Quick answers

• Waterspeed detects tacks and gybes automatically from GPS data.
• No manual tagging or button presses are needed.
• It works for sailing, windsurfing and wingfoiling.
• After each session you can review speed loss and consistency for every turn.

What’s the difference between a tack and a gybe?

A tack turns the bow through the wind (an upwind turn). A gybe turns the stern through the wind (a downwind turn).

In both you either keep speed or lose it. The difference shows up in your entry and exit angles, in how consistent your turns are over a session and in how they get worse as you tire late in a run.

How does Waterspeed detect tacks and gybes?

Waterspeed uses GPS direction, speed and heading changes to identify when you change course through the wind. You don’t tag anything or press buttons mid-session, and you don’t have to reconstruct it afterwards: each tack or gybe is picked up from your normal movement on the water.

What the data captures

Waterspeed breaks every tack and gybe into four measurements:

• Entry speed: how fast you were going when you started the turn
• Transition time: how long the turn took from entry to exit
• Exit speed: how fast you were going when you had power again
• Speed retention: exit speed divided by entry speed, as a percentage

Most riders have never seen their speed retention. 45% retention means you came out with less than half the speed you went in with; 72% means you kept more than two-thirds. Multiply that gap by every tack in a race or a long session.

What you’ll see after your session

Once your session syncs, you can review:

1. Your track: every leg, every turn, and how clean (or messy) your lines were.
2. Speed before, during and after each turn, which shows smooth exits, overcooked entries and the turns where you stalled without noticing.
3. Patterns across the session: early vs late tacks, port vs starboard, one spot vs another. Over time this tells you which turns you can rely on and which you can’t.

Is my problem the entry or the exit?

Most tack problems start either at the entry (angle and timing before the tack begins) or in the exit and rebuild after it. Find out which one you have before you decide what to train.

Entry angle and timing

Entry problems happen before the tack begins:

• Coming in with too much or too little speed, which shrinks the window for a clean transition
• A poor point of sail on entry, too close to the wind or too far off
• Starting the tack too early or too late relative to a mark or position

In Waterspeed, entry problems show up as inconsistent entry speeds. If your entry speed ranges from 12 to 22 knots across five tacks in similar wind, work on setup and timing before you touch the turn itself.

Exit and rebuild

Exit problems happen after the tack, while you get power back:

• Slow or mistimed sail handling during the transition
• Hesitation in the exit stance
• Losing momentum before you’re fully powered up again

They show up as low speed retention after a good entry. If the entry was clean and the transition time reasonable but you still came out slow, look at the exit.

What is good speed retention through a tack?

There’s no single benchmark for every sport, wind or level. As a reference, recreational to intermediate windsurfers see 40 to 65% speed retention in moderate wind. For other sports:

• Wingfoiling: very variable with foil and conditions; riders working on their tacks typically see 35 to 60%
• Sailing (dinghy or keelboat): transition times and retention vary a lot by class, but consistency across tacks is a strong sign of technique

Consistency matters more than any single number. A rider with 55% on every tack is in a stronger position than one averaging 65% with swings between 30% and 80%, and the consistent rider’s next step is easier to coach.

Here’s a real Waterspeed wingfoil session: three tacks in similar conditions, all within two minutes.

• Tack 1: entry 13.5 kts → exit 9.7 kts, 15.2% speed loss
• Tack 2: entry 13.7 kts → exit 7.8 kts, 23.4% speed loss
• Tack 3: entry 13.3 kts → exit 8.3 kts, 20.4% speed loss

Entry speeds are within 0.4 knots of each other and the wind didn’t change, yet tack 2 lost 8 points more than tack 1. That points to technique, and tack 2 is the one to replay in your head on the drive home.

How to use the data without overthinking it

• After every session, review your last five tacks instead of the whole session. Look at entry speed, transition time, exit speed and retention until you know your baseline.
• Work on your average tack, since that’s the one that costs you in races. Bring your worst tacks closer to your best.
• Set one target and track it across sessions. If you average 48% retention, aim for 55% over the next three sessions. Change one thing at a time (entry timing, exit stance or sail handling) and see what moves.
• Watch trends more than outliers. One bad gybe happens; ten bad ones tell you something.
• Compare sessions side by side to see how your tack metrics change over weeks.

Compare port and starboard, and use clusters

Almost every rider has a strong side and a weak side, and most don’t know how big the gap is. Group your tacks or gybes by side and compare their average speed retention. Judge clusters of turns: one excellent tack proves little, and so does one disaster caused by a wave or traffic.

Review the full sequence as well. The five seconds before the turn and the ten after matter as much as the turn itself, and entering too slow is the most common root cause of a big speed drop and a weak exit.

Five habits for more consistent gybes

1. Decide early. Most inconsistent gybes start too late: overpowered, heading into chop or too close to a mark, then rushed with a big save.
2. Carve the turn. Start progressively and let the arc develop. Pivoting abruptly sheds speed and needs a bigger recovery.
3. Time the transition. Flip the sail or wing, or change hands, when the equipment has turned far enough downwind. Too early stalls the turn; too late turns the exit into a scramble.
4. Exit with drive. Look where you’re going and re-power early.
5. Train one part at a time: entry, carve, transition, exit.

Can a smartwatch detect gybes accurately?

For training, yes: a good watch paired with a watersports app is accurate enough to show patterns over time (how many turns, where, speed before and after, and whether you’re getting more consistent). Detection works best when the manoeuvre is distinct, the GPS signal is stable and the software understands the sport. Crowded, gusty, stop-start sessions near shore are harder. Use the right sport profile and wear the watch snug, outside the wetsuit cuff.

Who this is for

Tracking tacks and gybes is most useful if you sail or race regularly, windsurf or wingfoil in variable conditions, or train solo and want objective feedback. It also helps if you want to improve without turning every session into “serious training”.

Why turns matter more than top speed

Top speed is the number people share and the one on challenge leaderboards, but most races and sessions are decided in the turns. A few knots of top speed mean little if you bleed 40% of your momentum every time you change direction.

You’ll find your tack and gybe breakdown in the session detail view after your next outing. For the other numbers worth reading after a session, see Beyond top speed.