OK if I have a wave sail that is supposed to use a 4m mast and the sail has an adjustable head turbin and I use a 430 mast in it. How will it affect the sail? I think the tip won't flex off in gusts and it might be harder to downhaul so the leech probably won't twist off and open up, which means the top end probably wont be that good if so does that mean the bottom end would be better to get going earlier? will it rig fuller in the main body or flatter?
Quadman depends on how much it is dropped down. All your changes you listed are right
My 5.2 rigs on a 400 with 28cm extension so on a 430 it is sweet for a heavyweight guy as being dropped down the mast about 4cm makes it ever so slightly less twisty and with a stiffer foil so thus more powerful - so it can be a good thing
But a 4.5 that is designed to rig on a 400 and you drop it down the mast a good 15cm or more is starting to get sus and it won't be setting right - so it can be a really bad thing
Also check luff length on your sail as some sails that recommend a 400 mast have luff lengths that are not far off 430!
i have a 6.7m severne code red,luff is 464cm. the correct mast is 430 enigma, it snapped at join.
i now use instead the bottom half of a powerex490 and the top half of a tushingham 430.
the sail rigs so weird,luff material is very loose down low, it actually shakes while sailing and fullness in sail is very deep.
biggest problem i have is the cams keep falling of the mast,apart from this it sails ok.
Thanks for the replies my sail has a luff just under 430 I would have thought they would recommend a 430 rather than a 400 with a lot of extension. But I guess for some reason it was designed on the shorter mast.
The top of the mast is softer than bottom. A so called constant curve of say 12, deflects 12% more at the top than at the bottom, even a so called stiff top is softer at the top. So when you use a longer mast than what it was designed for, the curve of the mast does match the curve that the sails luff was designed for, so it may not work as well.
I would be interested to know when they manufacture masts of different sizes, if they just cut stiffer bottom part to make the appropriate size (within a sensible range and type, considering SDM tappering etc). Bit silly cutting a 530 down to a 370, but afterlooking at how the IMCS formula works and doing some sample calculation do they really make for example both 430 a 400 masts or do they just cut the bottom of 430?
For example I get a 430/21 deflects 175mm at the middle with a 30kg weight and shorter
400/19 deflects 155mm at the middle, just 2cm difference...
BTW the IMCS formula is
IMCS= length[cm cubed]/(deflection [cm] * 216225)
