I have only one sail to support this in a Stealth F16.
All IMO of course.....
The T foils make the ride down wind very much smoother and you can drive the boat much harder. There were times while I was getting used to it that I was thinking that "I'll need to bear off in this gust to stop the bows going too deep, when in fact I did not; the foils gripped and the boat just went faster.
I agree 100% with T_A that they are adding drag as they are holding the back of the boat down and you could go faster with crew weight further back.
but you run out of crew weight ! At some point you have to shed power to keep the bows out (and so not going at full speed). Yes, by adding weight to the back of the boat by moving back you fix this, but you can only get so far back.
From sailing the boat only once, I can see that it will by critical to sail the boat all the time with the foils not dragging until you need them. The foils could make people lazy as the bows just don't dip anywhere near as much.
Consider this
2 boats are exactly the same except one boat has T foils on the bottom of the hulls.
Boat A and boat T (has the foils)
In light wind with NO waves
Boat A should be slightly faster than boat T as the T foils have more drag.
In light wind with waves
Boat A might be faster as it has less drag, but, boat T will slop around less on the waves as the T's prevent some of the wave action moving the boat around (so the rig shakes around less), but boat T has more drag and this will be compounded by the wave action.
In moderate wind and small waves
Boat A should be slightly faster as it has less drag, but boat T may have some small benefit from the more stable platform
In moderate wind and waves
Boat a might be faster as it has less drag, but, boat T will slop around less on the waves as the T's prevent some of the wave action moving the boat around (so the rig shakes around less), but boat T has more drag
In strong wind with smallish waves
Boat A might be slightly faster as it has less drag, but boat T will have benefit from the more stable platform and will also be able to drive the boat much harder downwind as there is less probability of pitchpole.
In strong wind with big waves
Boat A might be slightly faster as it has less drag, but boat T will have benefit from the more stable platform and will also be able to drive the boat much harder downwind as there is less probability of pitchpole.
Now my views are thus :
1, T foils add a little (and it is very little) drag as you have more area in the water.
2, T foils make a massive difference sailing downwind in the windier stuff as the boat is much less tippy for/aft and so can be driven MUCH harder. Once you are standing at the back of the boat, you cannot go any further back.
3, When the wind is lighter, crew positioning is vital to ensure the foils are not dragging.
4, I've not sailed the boat in waves yet so cannot comment.
Another thing, over the last 8 years, I have gone from sailing a 20 foot boat (Hurricane 5.9) that was a dream to sail down wind in the big stuff, loads of volume up front and so we did not really factor in pictpoling into many sailing days
Then I moved onto a 17 foot 6 boat were you do have to be a little more carefull (still loads of volume up front). I've now gone to the Stealth (waiting delivery) and we'll see how that goes, but on my first sail,it was behaving more like and 18+ foot boat than the 16 foot boat that it is.
IMO T foils are the dogs danglies....
