I'm having no luck at all with a flat sail. I recently installed a Ronstan cleat,so that I get good, positive control of the outhaul. When I pull the sail flat. The boat stops. If I give it 50-60 mm of draft and loose mast rotation, it goes just fine. I was matching course and speed with Matt & Zach (Viper)with everything "loosey-goosey". As an experiment, I tightened the main slightly and they began to close immediately.
And JC is abroad these days. You'll probably run into him before I do.

This puzzle is great fun! Life is good!
Thanks for all your help.