Join Date: Feb 2012
Location: New Orleans Louisiana
Thanked 123 Times in 117 Posts
Rep Power: 5
Re: VMG with lots of tacks
To my knowledge there are no boats that sail fast enough, or accelerate fast enough, including the new AC45's (that accelerate from 4kn to 18kn in 80 foot) that justify just tacking. The first guys to the weather mark will be the ones that tack in the shifts. So the tack on throws. Ideally this means they are always in phase with the wind shifts, and may sail a 10-20% shorter course than someone heading off to a corner.
The only reasons to head to a corner is 1) you know there is a wind shift there 2) more breeze (particularly good in light air), 3) you are way behind and hoping to get lucky 4) tactical reasons involving a specific boat or boats).
Think about it like this... Two boats start together, and are sailing at the same speed parallel to each other. Then a five degree knock comes in, boat A tacks, boat B stays. The boats are now sailing 10% apart from each other, with boat A sailing 10 degrees closer to the mark.
A few minutes later there is another shift five degrees the other way. Boat A tacks, so the two boats are now again on parallel courses, but A has gained significantly to windward on the other tack. Boat A is also moving back to the center of the course, while boat B is headed further to the right side.
Another shift and A tacks again. B stays put. Again A is sailing 10 degrees closer to the mark than B is.
This goes on until B hits the layline and tacks. A however has constantly sailed in a lifted breeze and so is in the middle of the course. Any further lift for B is waisted since they are on layline, while A can still take advantage of it, and a knock for B hurts them since they may no longer be able to make the mark, and are sailing out of phase with the wind.
Of course knowing how to tack the boat properly, and knowing how to get it back up to speed is critical for this to work. As well as having a feeling for the speed of the shifts (how fast the wind is clocking), and how long it takes the boat to get up to speed. So a shift that I might tack on in a 12' ultralight skiff might not be worth it on a 50' heavy cruiser because of the amount of time it would take to return to full speed.