hi again minicatman,

Here are some tricks that might suit your non-calculations mind:

Place the cat in a swimming-pool and push sidewards against a hull. You can find with a bit of trying the point where to push so that the cat moves exactly lateral to the side (instead of turning his bow towards or from you). That point on the hull gives you exactly the place of the centre of lateral resistance for the whole combination.

Searching the centre of effort for your (surf-) sail is very easy. I presume you use a surfwishbone as boom; so mount everything like a surfsail and hang on it with your surfharness with just one straight line to your wishbone. The point of the line where the sail stays in balance gives you the centre of effort.

Looking at your photo I'm convinced by the way that this centre is far more upfront then you stated earlier.

And please keep your downhaul much more tight. It will change your sail directly in a much nicer wing. And it will help you coping with the weather helm by moving the pressurepoint of your sail closer to the mast.

Finally: Hanging out with a harness connected to the boom seems to me no problem for your mast fixed on the cat