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T-foil on i14??
Posted: Sat Oct 09, 2010 12:58 am
i was wondering (maybe its a really stupid question) the t-foil for i14 can move like moth foils?? or it´s just for stability and cant be controlled by the skipper?...cause i was thinking on putting a tfoil on my boat...and i dont have a clue about it...
Re: T-foil on i14??
Posted: Tue Oct 12, 2010 11:37 am
Hi. Yes the hydrofoil on the rudder works much like that on a foiling moth.
On 14s - Upwind -The usual mode of operation is to apply a positive angle of attack upwind, effectively lifting the stern and pushing the bow down. This does a number of things dynamically - ie, it maintains a maximum waterline length and reduces the transom dragging in light air, and as the boat speed picks up it does a number of other things, eg, it returns the stern wave (pushes it back down) reducing induced drag, it forces the bow planing sections down, making these lifting sections do more work, and it stops the boat 'flaring' (bow planing too high) and generally maintains a bow down attitude (which is quite difficult at first to get used to when you are trapezing as it feels like you are going around the front all of the time!)
Downwind we put the hydrofoil into a slightly negative angle of attack just before we bear away which helps us to make a smoother turn and gives a little more stability while the crew is in the boat hoisting the spinnaker as it keeps the bow up (out of the waves) and anchors the stern down (or it feels like it) This makes the everyones job a lot easier as the boat feels nicely 'planted'... The once the hoist is done and the crew is trapezing we start put the hydrofoil back into a positive angle of attack - adjusting it to have the most amount of lift we can cope with in the wind and wave conditions - so in flat water we are on maximum foil lift (positive A of A) just like upwind, but in steep waves we could be in a negative angle of attack to prevent nose diving.