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Old 15th April 2007, 11:24 AM   #4
Roger
Dream Team - School Guru
 
Join Date: Aug 2006
Posts: 2,110
Default RE: the toes up thing

Hi Thomas,
The reason that the WS hardware guys make stubby (appox. 4" long inside the mast), short (approx. 15 cm of adjustment), medium (approx. 25-28 cm of adjustment), and tall (approx. 45-48 cm of adjustment) is so that you do not have more than about 15 cm of extension up inside your mast.
If you put a tall extension set at < 25 cm inside your mast, you end up "stiffening" the bottom of the mast so it cannot bend the way it needs to because it has a stiff extension inside it, which will not allow the mast to bend all the way down to near the base.
This can cause some real problems with sails that have a low foot batten as the batten won&#39;t rotate correctly because the mast is too stiff. It can also take alot of shape out of the bottom of some sails.
If you are using a 48 cm extension on your 6.6 m2 rig, with a 460 mast, you really need to get either a medium or short extension (depends on the luff length of your sail) to get the best shape and batten rotation in the lower part of your sail.
Can you use a 42 cm extension on your 460 cm mast to make it into a 490?
That depends.
If your sail is designed for a 490 luff length on a 460 cm mast with 30 cm of extension, then yes you can do this very nicely as it&#39;s the way the sail was designed. A 460 cm mast has a 12% bend ratio, and is rated IMCS 24-26.
If your sail is designed for more that 508 cm luff length, or is designed for a 490 cm IMCS 28-30 mast, then no your mast will be far too soft and you won&#39;t get the correct tension and shaping of the panels in the sail as the sail was designed to work on a much stiffer mast (490 cm IMCS 28-30).
Hope this helps,
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