OK, cutting away all the crap that is flying around. How I set up my Inter 17 Alu mast.


I wanted to have power, but the mast must fit the prebend cut into the sail.

1, I "Eyeballed" the sail and then ran a cotton up the luff having pegged it out to get a rough idea of the prebed in the sail. Mine came out at 22mm (IIRC).
2, I wanted a stiff mast as the Alu masted Inter 17 is underpowered, so after some fecking around I set the rake on the spreaders at about 10mm (I think).
3, I then rigged the boat and hoisted the sail. I then took the sail off the hook at the top but the sail did not fall down. I then wound on prebend until the sail fell down. Thus implying that the sail shape matched the mast shape.
4, I then tipped the boat on it's side and measured the prebend by tieing a cotton from the top of the mast to the gooseneck and paied it tight to the mast. I then measured the gat at the spreaders - 22mm.
5, When I did this the mast actually looked quite bent and so I was not sure this was right. I went sailing in lightish (F3) wind with a spanner in the tramp bag and sailed for 20 mins, reduced the prebend and sailed again. Boat was slower so I convinced myself that the mast with this much prebend was right so I put it back in.

I never changed the prebend setting, I just left it. I just used the downhaul, and with the Alu mast, you should be aiming to get the bottom of the sail touching the mast spanner (my sail had the luff eye at the bottom of the sail, some had the eye further up).

I also cross validated but putting the sail back up, Max mast rotation, max downhaul, sheeting the mainsail in tight and then ensuring that the aft diamon wire was not too slack.