David,
when you increase the power by making the foil deeper (more draft) the drag will also increase. If we say the windspeed is relatively constant there will be a given draft which have the best lift to drag ratio for that windspeed. If we sail with more draft than optimum, we will be slower than somebody with optimum draft or even less than optimum as they have less power but also far less drag.
Perhaps I should do a graph..
This is all very theorethical and in real life it is most important before you get out on the trapeze. It is especially important in light winds in my opinion!
I'll dare to say something about the second question as well. Draft and airspeed are also part of deciding the point of stall to a greater or lesser degree depending largely on the speeds and angles you work with. That is my understanding at least.
There is a good trick you can use this full camber for. In light winds if the leg is long enough and you are having trouble catching/overtaking a nearby boat ahead when sailing to windward, try easing the outhaul and downhaul to increase camber and start to pinch slightly. If done properly you fall back a little but you lift above the other boat. You can then bear off a little and trim accordingly for greater boatspeed. This helps get you past the other boat. If they try luffing they slow down, plus you have more lift from your boards with the increased boatspeed.
Cheshirecatman
