Foil Trim - how to get the balance right

[Greg_F]

Thanks for the shout out Matt!

The other thing to consider is that the rider will generally move forward on the board when the foil is moved forward.

To fly straight the force of gravity acting on the whole system needs to be equal to the lift generated by the foil, and the effective summed location of the COGs of the rider + board + foil must be directly above the effective centre of lift. By effective I mean taking into account the moment generated by the stab so your picture can be representative assuming different stabilizer shimming.

[Matt]

Continuing the idea that you shouldn’t foil drive onto waves but rather chip into waves, because the trim will be better

The end is near: we'll all be electric in <5 years

Just to make it clear, this video below is what I’m talking about. This is the way to progress with FD. Take off on unbroken clean waves, and the two critical steps: keep your front hand on the nose of the board while you standup, this keeps the board trim correct and the nose down while you are still on motor power when you popup, do it deliberately in a clean pop, to clear the motor from the water, this means you never have your feet forward, you are straight into riding mode Step on…

This video is a perfect example of why motoring on foil onto waves is a complete disaster. Also a good example of why efoiling looks so terrible on wave when done this way.

Note how he has to pump while on foil even though the wave has plenty of energy. This is because so far forward. And the turns are terrible and keep bogging.

He is standing at least 30cm forward of where he should be standing, and it shows. This is exactly the issue

[Matt]

Riding a foil without a stab is possibly a good way to feel out the trim of a foil, as the idea behind this thread is that you should be standing in such a way that the stab is not used at all, in which case you’d not miss it much if you removed it

my beautiful place

[tavis]

So in the plane analogy the back foot is your elevator and all pitch control happens via back foot pressure. If you were to stand on the front foot and balance you would glide fully trimmed. So instead of pushing down with your front foot during a pump think about lifting the back foot. This doesn’t seem to be what Kane does as his back heel never even comes up (in that video anyway).

[jondrums]

@tavis

if you were to stand on the front foot and balance you would glide fully trimmed.

I disagree with that one personally. I’m working pretty hard to get weight equal on both feet when gliding and when pumping. For downwinding it is almost a requirement or you’ll burn out one leg fast

[tavis]

Yeah I don’t think it would work either unless you had a back foot strap to pull up like a plane’s elevator can do. So the question still remains where it might be best to have your your feet. Obviously your front foot needs to be forward of the main wing and your back foot behind it.

[Hdip]

Straddling the front foil.