It is possible to design watercraft that will travel exactly where wind come from.
Using wind turbine with horizontal or vertical axis that power propeller in the water that boat should be able to have net resultant force propelling craft straight up the wind.
I wonder if is even theoretically possible to design such a sails configuration that do this same ?
I can imagine the closest to ideal could be configuration of two kites flying 8 figure always on opposite wind direction with resultant vector straigh forward...
Can't do this same with sails I am affraid 
sorry this dilema belong more to general discussion then windsurfing in particular - so I move topic there for these interested.
Anyway I hate to ride on windsurfer straight down the wind even that possible _ I think that riding straight up will be evenly awfull 
So, what about a fairly wide catamaran with 2 masts - one on each hull, abreast of each other, and for simplicity sake rig only a mainsail on each one. Point the boat directly into the wind, but sheet the 2 sails into the centre of the trampoline. Now you have 1 sail on a starboard tack and 1 on a port tack and the boat itself head to wind. The 2 sails would work fairly hard against each other, trying to tear the hulls from each other, but each would have some vector in the forwards direction, as any 1 sail on any yacht with the sail sheeted correctly would - that's how a normal yacht makes its way to windward.
It'd be pretty inefficient, but my guess is that it would slowly make way directly into the wind. Would love to see it tried.
If it got up windspeed that would be that.
