INVESTIGATOR 563

Hi Ian. The best thing to do is to simple put the sail you want to use on and try it out. There are several things you can do to adjust for lee or weather helm.
Rake of mast, reduce main sail area by reefing, use different rudder( flatter or more foil shape), bow sprit, reducing the amount of centreboard used, the set of both sails ( flatter or more shape), etc etc.
Would be a great idea to set the boat up with each headsail in turn, get one set up handling nicely, note all the settings including amount of wind and write it all down. Repeat for each of your other headsails, then when required, you will know the best set up for each headsail.
Ideally, with around 5 to 10 knots of breeze, the boat should have neutral helm. With this, with increasing wind and therefore more heeling action, the weather helm will gradually increase as well which is exactly as you would want it. A yacht with lee helm is a horrible thing to sail, as is one with too much weather helm

Cheers

You’re absolutely right Peter. My main interest in that very small jib in the picture (I don’t have one like that) is that with the second reef in the main and my #2 jib in about 18+ knots with both sails as flat as possible, I found a lot of lee helm which is scary in a blow. But you are right that more practice and tweaking (like trying more backstay tension or even more twist to spill wind in the top of the sail) is needed.