RE: Foot Strap Positioning
"I have a new ... okay now outdated F-type 148 which I am using a 10m NP RS-S sail. I noticed that even with the stock 56 fin, the board occasionally rails up, so to get more control I end up moving my feet onto the rail. The problem is now they are out of the straps somewhat and I soon will have a 63cm fin for added light wind power."
I've never had that probem on the F-Types.
I think this may be more a tuning or fin size issue than where the footstraps are placed on the board.
Normally "railing up" starts to happen just before "tailwalking" and that's pretty much a fin size and tuning vs speed issue.
If the board rails up and tailwalks you can move the mast foot forward slightly (provided you don't already have it all the way forward in an attempt to get better upwind performance) to settle the board down. Yes, you will go a bit slower, but sticking the board to the water and lengthening it's waterline length slightly (I'm talking moving the mast foot 1-2 cm here 3/8-3/4") is about all you can do out on the water.
Changing down to a smaller fin, will really solve the problem, the main issue being too much "lift" from the fin for you to control with the available leverage.
Is this happening with your 10 m2 rig? Perhaps you need to rig down to say 8.5 m2. It could be you are simply overpowered and perhaps raking the rig upwind some which tends to lift the upwind rail and in some cases the whole board.
How far do your feet go into the footstraps? Perhaps just an adjustment to place your foot a little further out would give you some more leverage.
Do you have particularly small feet? I have very short (size 7 US) feet but they are wide so I end up setting my straps one hole wider than
back hole in the back and back hole in the front, and then cinching the straps down tighter so the strap holds my foot onto the board nicely but I can move my heels along the rail to give better control on different points of sail.
Also, where are you running your mast foot? Front, middle, back of the slot?
Hope this helps,