My experience has been with my Starboard Z-class which works much like a formula board in planing. I found that having the sail fully back helps get the board planing earlier in light winds and you haveto plane to get anywhere with a formula board.
When the mast is forward I need to tilt back too far to get the centre of pressure over the fin and the sail drags in the water. Moving it back helps to solve this problem by keeping the mast more upright.
In strong winds, moving the mast foot forward helps to make the board easier to controle.
In displacement with the centreboard down, moving the mast fully forward helps to enguage more leeward rail edge and this makes a very big difference to upwind progress. Roger has previously suggested that tilting the board to sink the leeward rail helps in planing upwind as well. I guess if moving the mast foot forward can help with keeping more leeward rail in the water without adversely affecting your planing then you should go upwind better.
Last edited by tonymatta; 26th August 2008 at 11:45 AM.