Here is my advice, and god knows I had realy problems with this, but then I red an
article on internet and it is very good guidance.
Rear line - put on the 1/3 boom lenght
Front line - 1 fist apart
FOR FREERACE&SLALOM SAILS, put everything 1-2 inch more forward.
This works I have 1 boom with marked 3 positions for the 3 sails.