Putting a sail rig on a kayak causes so many problems that the result has so many compromises that I just don't like any of them!

The high ctr of pressure of a sail causes rotation momemnts that have to be countered.

Sailing across the wind, causes side pressure that has to be countered w/ centreboard or something.

Multiple lines plus paddle causes confusion.

Sail size gets in way of paddle recovery strokes.

Kite types have high work load (nice low ctr of effort possibility though)

necessary use of a rudder for steering. (maybe just skeg & paddle)

So some thoughts only:

1/ Instead of medium small crappy sails, why not use an efficient very small shaped foil. The small size may reduce the overturning moment.

2/ Instead of using a fixed mast, why not use a universal foot like a windsurfer. The line tension is just the same, but the foil can be tipped over to further reduce the moment.

3/Instead of a rudder and centrebd system, use a rear larger rear skeg and either use a retractable or fixed FRONT skeg to balance the action of the rear skeg, getting centrbd and turning action w/ one move.

4/ and for the lines - tough one (there is a possibility of a closed system using only one line-but I have to do a full scale mockup - way later)

some frustrated ideas anyway

-mick