does mast position change with board size and weight ?

[slowboat]

A specific example. Take a 140 cm board with mast optimally positioned. Measure mast to front foot position=50 cm. Now, if I put the same foil on a 112 cm board, do I still want the same 50 cm from mast to front foot, or might that change because the boards are so different in size, swing weight, etc? Hope the question is clear, thanks

[edt]

You always stand with your center of mass exactly dead center over the hydrofoil wing.

Now if you have a really really long surfboard that is really heavy and you put your hydrofoil all the way at the tail of the board you will have a lot of weight at the front of the board. This means you will have to put your foot position really far back. Now suppose you put the hydrofoil wing at the exact center of a small board and the exact center of a large board. Now your foot placement will be exactly the same in both boards.

so yeah, it can change depending on where you want to stand on the board. Remember that the mast position is not the center of the hydrofoil wing. The mast is always set forward a few centimeters from the wing, this means that the center of the hydrofoil wing is always a bit in front of the mast so you have to set the mast a little bit behind the center of the board, that is if you want the hydrofoil wing to be directly under the center of your board.

It's all up to you how to choose to set things up. I think most kiters like to have a bit of the board out in front instead of planting the wing directly under the center of the board, but I kind of like having the wing directly under the center of the board. All personal preference. There's no "optimal placement" for the mast, and depending on where you set the mast the foot position will change depending on the weight of the board.

If you have a really light board you can pretty much ignore the weight of the board and just put the feet centered directly over the wings.

[cwood]

absolutely it does and it can be quite a bit. All about center of gravity as it relates to stable flat flight. Extra weight out to the nose has quite a large lever effect, heck, even moving your melon head forward and backward will change the weight distribution.