Interesting breakdown on trimming a board without rider attached from @Greg_F in this thread, and Greg seems to advocate for a trim that matches what I’m suggesting:
Personally I like to be just a touch forward of the balance point, around 1cm or so - Center of Lift (CL) 1cm in front of your Center of Gravity (CG)
Which I guess speaks to why people like moving the mast forward, if they otherwise change nothing, it starts to make the foil feel more alive, as the trim gets better:
Some notes
Let’s assume your original position was perfectly balanced, meaning that if you jumped off the board in flight the foil would continue to fly straight. This means that as long as you stand directly centred over the lift of the foil when you unweight the foil it continues to fly straight.
This is a good idea for trim test of the board. The same should be true when you stand on the board with evenly weighted feet. If you don’t glide with even pressure in both feet, then your trim is out of whack