Have seen a design made US (probably via a sailinganarchy link) that they cal
'delta' and I consider the correct way to do it - the sail is a twin with common luff and split towards the leeches. Only one side works and there is no subpressure on the lee side - effect: it does not work
like a sail but rather like the vanes of a windex. The boat is not pushed forward - rather the stern is pushed back in line with the wind. This is what you want. The single
sheet sails flown aft DO NOT work
- they push the boat forward only making things worse.
2) yes, you can fly the sail from the topping lift
- provided it is strong enough and does not stretch (spectra?) - because you will want to make it pretty tight.