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?

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QuadMan said...

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?

I have a simialr setup . I rigged the 4m sail on the correct mast (400) and then on my 430 with the adjustable head used. With the correct mast the sail had a nice shape..a belly for power lower in its range & a nice loose leech for twist when necessary. When we rigged it on my 430 ( actually prob a bit shorter as it has a bit cut off it) I could get the leech to loosen ( not as well ) but I noticed it had no real belly as the mast was too stiff.So it would be more gutless low down in its wind range and not quite as controllable as it should be in the upper range.I think my 430 was also a bit stiffer than the sail required too..
So the sail won't perform as well as its designed but still its better than I expected for a mismatch & will get me out on the water..

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

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QuadMan said...

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?

Depends on the type of mast/s, whether it matches the sail and what type of sailing you're doing. May be more of a problem with flex-top Pryde masts than with constant curve masts from other manufacturers due to the fact that the bend in the top of the Pryde masts appears very critical to rig performance. Have you ever seen a Pryde wave sail with an adjustable head? (was told by a Pryde dealer that adjustable heads, particularly on Pryde sails, are a no-no and stuff up the leech tension in the head of the sail as well as the twist). Also, if the sail manufacturer fitted an adjustable head to the sail then surely it would be ok to use a longer mast?

I've got a Severne Blade 4.5 and the recommended mast is a 400 rdm. I've sailed it with the 400 but prefer using a 430 rdm in it (both Ezzy rdm's), though if I was actually using it for what it was intended (i.e. for wave sailing and not high wind bump n' jump), then the 400 may be the better option.

From what I can gather, using a 400 mast where the manufacturer specifies this mast will make the sail slightly softer and more responsive (than 430) whilst the 430 will stiffen the sail slightly (assuming both masts are same brand/model). Really boils down to what you're using the sail for. If it's for blasting & bump n' jump then 430 would probably be fine, though for wave sailing I'd go for exactly what the manufacturer recommends.

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.

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QuadMan said...

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.

My KA 5.3 Koyote freeride sail has a 423cm luff and rec mast is 400 IMCS 19 (also has adjustable head). I asked KA sail designer why not 430 and he said that putting the sail on a mast with a stiffness of IMCS 21 (which all 430 masts are) would compromise the sail.

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)