From a complete bumbly/newbie...
Flappy topped sails are going out of fashion (I think, in Cherubs anyway) but in theory they take area out of the leech, low down (where it may not be much good anyway and makes gybing more difficult) and put it into creating a head which is of use instead of just knocking you over...
Loco's flappy top now sets beautifully simply by putting screw-type batten tension adjusters on.
I hope I can accurately set tension for different wind strengths and allow the top to automatically free to prevent over-powering - who needs adjustable uppers? (well, they might help as well actually)
Loco's main sets much better now:
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