Tail kick / foil rake

I am trying to wrap my head around the details of raking the mast either with shims in the tuttle box or by adding tail kick or rocker where the foil attaches to the board. Please review the attached image to help clarify my text. If I understand correctly the current idea is to rake the foil aft by a degree or two. This is a bit counter intuitive to me because when the board is riding level in the water the foil wants to dive deeper in the water. Do I have the orientation backwards? If not can someone explain why aft rake is beneficial?
ManyThanks!
David Buckley

Paduca is spot on! Having the fuselage parallel to the board doesnt mean that the wings are parallel to the board too! Most often, the wing's "0-lift"-line (centerline but not exactly since the wings are most often assymetrical) is tilted up a little compared to the fuselage. You compensate for this by angling up your board a little. (Middle pic)

Most often riders angle their board up a little more than to just compensate for the wing angle for a multitude of reasons. A very noticable one being less drag when accidentally touching the water because only the tail hits. 1 degree is 5-10cm in nose height, which makes a huge difference! Another reason can be to change powerdistribution over the feet. Simply because the front foot is relatively a little higher it will become a more "front foot preassure" setup. A last reason why I would adjust rake is also to have the board lift / drop less in gusts by adjusting the angle at which the board is riding against the wind (if you get my drift), at different boardspeeds your foil will be at different angles in the water, for me this means that in more wind I have to increase rake just a little to keep the board level with the higher speeds and make sure wind passes under / over it instead of pushing it up/down and changing my balance.

So some general rules of thumb for rake:
- if you often catapult when hitting the water with your board, your nose is too low so you have to increase rake
- if you have trouble lifting off in ample wind, you might have too much rake.
- if lower winds, less rake
- if higher winds, more rake
- if your board rises in gusts (and evrrything else is set right), decrease rake
- if your board drops in gusts (...), increase rake

A setting between 1.5-2 degrees is a very good starting point for any setup (my go to for both my race and freeride setup is 1.7). I meassure this with my phone and an app, first putting the phone on the board right next to the foil and calibrating to 0, then puting it on top of the fuselage right above it and looking at the value. Just remember when changing rake, 0.2-0.3 degrees is quite a noticable change so go easy ;).

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utcminusfour said..
Thanks Gents! What is the best way to make the rake adjustment?

You didn't say cheapest. Something like this: marseille.glissattitude.com/windfoil/u37872s1-divers-cales-de-reglage-rake-divers-2019.html
Or use that as inspiration, you being much more clever in constructing things than I. Advantage of their kit is that it comes with a bunch of shims with specific dimensions (e.g. 1, 3, 5mm) for the plug and play crowd or if you need to make a quick adjustment at water's edge.

Edit: if you are using a tuttle head with a plate, I've read that people "shim" the base plate with thin layers of eva foam (e.g boom grip). It's sandable and easily stackable. If you have access to a 3d printer then you can do all sorts of creative things.

Thanks everyone! I bet attention to the rake will keep my dryer! This forum is huge help!