Suppose There are two masts of the same size with the same mast curve % but a different overall stiffness for instance 28 Vs. 30.5
Couldn't one just apply more downhaul to the stiffer mast to get it to the same bend to fit the sail intended for the softer mast?
You often see a sail that can be rigged on two sizes of mast - each mast has a different stiffness but the same bend curve. The sail will set roughly the same on both masts but will behave differently due to the stiffness. The softer mast will potentially handle gusts better, bending more easily and bending more. The stiffer mast will return (reflex) back to its original position faster, potentially providing a more efficient sail. Some heavier sailors might prefer a stiffer mast, some speed sailors might prefer a softer mast.
Bend curve is a measure of "where" the stiffness is in the mast - for the same IMCS (stiffness measured in the middle of the mast) one mast model/brand can have a relatively stiffer top than another. Hopefully all masts from a single brand have the same curve.
As a total newbie to this sport I thought I had no clew,then was told there is one on my sail!! pfffttt.I was lucky enought to be given an awesome 5.2 ezzy wave sail 07. I went and bought a SDM 430 mast for it,but have found that it may be to stiff for this sail as the battens get caught behind the mast and when the sail sets it clunks like Im sticking it into gear with out using the clutch Ha.
So is it mast with wrong curve(to stiff)?do I need to buy the recommended mast and use this one as a marlin rod?
With the same bend curve you wouldn't have to apply more downhaul. The sail will fit with the same amount of downhaul, but it won't react in quite the same way. The sail would have more foil tension, which may make it feel more direct but also the stiffer mast would affect how the sail exhausts. When the mast bends sideways at the head the leach tightens and effectively stops it from twisting further. A stiffer mast would require more force to bend sideways and therefore the tightening of the leach would occur later, perhaps making the head twist further. I'm just guessing here, 'cos I haven't tried it. Is it even possible to get two masts with the same bend characteristics but different stiffnesses? The only way I can think of testing this is if you compared (fx) a 490 against a 460 with a long base or extender, but that wouldn't be a true test because the bend curve would change.
Make sense?
Edit: must have been asleep there.. 2 posts down before I got mine in.
^^^ yep, what he said
I learnt this lesson trying to rig a Gaastra Manic on a Neil Pryde mast. The Manic was designed for a Stiff Top mast and Neil Prydes are Flex Top. The result was as you describe mybrosweeper - floppy top of the sail, but lower battens pushing past the mast and not rotating. I had to change the mast.
Now if someone can answer why a sail designer would choose to design around a particular mast curve I would love to know! What are the design trade offs? If the trade offs are minimal - which I think the are given the closeness of pro results - it would appear the sport would be much better off standardising the bend curve. Locking a consumer into one brand (or a least putting a significant barrier in place) is not a big picture strategy. Grow the sport, the overall pie gets bigger, all brands get a bigger slice. [/rant]
With those stats you will not notice any difference. I reckon 90% of sailors would not notice.
Still seeing as though they are both Hawaiian brands there would have been plenty of mix n match going on over there so ask Ezzy as suggested above, or does Hot Sails have a forum maybe?
Dave Ezzy or Jeff Henderson would let you know straight up
The mast curve helps determine sail shape, that's why it's important to get a mast close to the correct bend curve.
Mast stiffness affects the amount of skin tension in the sail and the sideways flex of the top of the sail.
If the mast is too stiff, it can feel "wooden" and non responsive, too soft and it losses power.
Generally heavy sailors prefer stiffer masts, and light sailors softer masts.
If your mast isn't ideal, rigging your sail is about getting the right compromise for you. If your bottom batten isn't rotating you can do two things to resolve it, either put more downhaul on or put more outhaul on to pull the batten away from the mast.
More downhaul will loosen the leach at the head, making the sail lighter in the hands and bringing the pull position forward. Too much will make the sail feel gutless, twitchy and difficult to handle.
More outhaul will flatten the lower battens more, also bring the pull position forward but most importantly taking away the power at the bottom of the sail. Too much and the sail will feel very unstable and gutless and with the power coming from higher up it may make it feel less manoeuvrable.
So, I'd start by putting on a bit more downhaul until the bottom batten unsticks. The bottom batten doesn't need to sit off the mast, just enough so you can rotate it with your thumb. If the leach loosens more than half way across the head then take some off and apply a little more outhaul instead.
When you think you've got it right, go sail it.
