dransy wrote:
and how do i know if its the correct curvature?

Sail specifications / trim guides should quote the recommended 'IMCS' (International Mast Curvature Standard?)rating, or range. It is also normally printed on the sail. You need to ensure the IMCS rating printed on the mast is similar. They generally will be though if the mast is the right length for the sail, unless you have a very old mast or sail. Some masts are built as 'stiff top' or 'flex top' which can also affect how a sail rigs on them.

As per above, a sail of 6.6 would normally rig on a 460 mast (with, as you say, around 10cm of extension if the quoted luff length is 470) and most 460s will be around IMCS 25.

Hi, not written on the forum before. Mast are set by IMCS (Index Monkey Centrally Suspended) A Monkey is a weight of about 20 to 25 kg. The sail is suspended at its top and bottom and the Monkey (weight) is pleace in the middle of the mast. The distance that the mast moves (bends) is the MCS and these measurements are indexed due to differnet mast lengths. Manufacturers automatically build their masts to the sails requirements, so most sails of the same size are identical in IMCS.

If you do use a 430 mast rather than a 460, I would just advise to see if the IMCS is with atleast 2 of the recommended, i.e. if you need IMCS 23 a 21 or 25 would be OK but the masts reactions in gusts are slower if u use a 21. This means, the mast tries to keep the sails best and most efficient shape and as a gust hits the sail the mast flexes. The mast responds and tries to retain the best shape of the mast. If the IMCS is low and the mast is soft then the leach of the sail will be too loose and the wind and power will exhaust from your sail too quickly. There are some good articles on the Boards website.

Hope this is of help, Getrad