We set up a masthead halyard for a Code0 on our Antigua
37 a couple of years ago. Being a nerd i wanted the sail to be as big as possible so we ended up with 64 fresh m2 of sail with a torsion line length of just over 16 meter. The sail sits on a 1,8 meter retractable bowsprit
. The builder
FP said it was ok as long as we would not charter
the boat. If we were, they proposed backstays
. We are not chartering the boat but i fitted the backstays
anyway and i am happy for that. We use the sail up to 12-14 knots apparent. To get the tension on the torsion line, we use a double 12 mm Dyneema
halyard that goes from masthead through the swvel in the sail and back up into a dedicated sheavebox. In retrospect i could have put the sheavebox a bit lower as the halyard has a tendency of twisting even though the swivel. To get tension is really important for several reasons, first, the more tension, the higher you can go into the wind. Also when wind picks up, it is almost impossible to roll up the sail if the front leech(?) is slack. Shafe is also an issue here.
We are really happy with it!