With the burgeoning Sportboat fleets and modern yacht design favouring high aspect keels, maintaining flow over the foils has become increasingly important.
To get a great start, line up slightly sprung sheets and hold your course until the boat is at full speed. Then gently steer up to close-hauled just before the gun goes.
With a boat to leeward of you, try to go straight while accelerating slightly lower than their angle. Even though you’re getting closer to the leeward boat initially, you’ll be generating better speed grip and lift. This in turn gives you more height and speed so you can lift off them.
Modern High Aspect Keels Need Flow At All Times
Crews, but particularly helmspersons must constantly be on the lookout to avoid stalling the foils. High aspect keels need flow. The helmsperson must execute smooth turns and maintain boatspeed to stop that from happening.
At the leeward mark start your turn when you’re around 2.5 boat lengths abeam of the mark. Do that and you’ll have way more grip on your keel and end up in a higher lane than boats still turning as they pass the mark. This is when the keel stalls and the boat slides sideways.
It’s OK if your arc takes you a little downwind of the mark before turning up. Again, the idea is that, as you finish the turn and actually pass the mark, you are already close-hauled.
Ducking a boat upwind requires the same consideration. You pay more for turning hard at the boat you’re ducking in a sportsboat than in a fat-keeled boat.
You’ll gain more by bearing away early, building speed, and doing a small head-up as you pass astern of the boat you’re ducking.
Pinching Causes Loss of VMG – High Aspect Keels Need Flow At All Times.
If you constantly pinch, your VMG will be worse with a skinny keel because you’re close to stalling the keel. The boat needs more flow to create lift. High Aspect Keels Need Flow At All Times.
Try adding a couple of tenths to your boatspeed by initially steering down a degree or two. You will almost always end up pointing as high as everyone else because you have way more flow over your blades.
A word of caution though, you can overdo it and start reaching around the course. High Aspect Keels Need Flow At All Times.