View Full Version : mast combinations
5th December 2007, 11:08 AM
I've got a 5.3 Severne Blade that has a 435 luff. Reccomended mast is a 400. To me 35cm of extension is too much. Looking at mixing my 430 and 400 PowerX skinnies for a better fit. Should I use 400 base and 430 top or vs verse? Thanks
7th December 2007, 04:25 AM
Its nt that much to get correct mast flex. (Some NP use as much as 40cm)
Think you will be ok with the skinnies to get correct mast lenghth but on SD I`d stick to using the extension.
Nothing ruins a sails feel more than an over stiff mast; they recommend the combo for a reason.ie sail was designed around 400 mast and its flex pattern.
Suck it and see ???
28th December 2007, 02:57 AM
The correct combination would be 400 base 430 top
29th December 2007, 07:58 AM
Hmmm... I would have used 430 bottom and 400 top. The reasoning is that the 400 bottom with rigid mast extension would make the bottom stiffer in it's curve, much like a 430 bottom.
Using a stiffer 430 top would make the curve very different from what the sail was designed for.
I don't think the Ezzy recommendations are a good guide as they probably have designed that particulat sail around that specific curve.
But, as always, the answer is as stated above: Suck it and see.........
29th December 2007, 11:56 PM
Least he can try it both ways, I use a 340 bottom and a 370 top, works swell on a SuperFreak, without being a mast genius, come to think of it I just figured out how to work my solar caculator, the stiffness on a combo setup has to a % of the 2, I have no clue which way it would be biased.
I rather like David Ezzy, so his site is a Bible to me.
30th December 2007, 04:17 AM
To Clarify, I mean that the Ezzy way of combining masts may not work for other brands with different sail design and construction techniques. It clearly works perfectly for the Ezzy sails which are designed around these combo's.
With all masts the top part has more bend than the bottom part. Also, as you go shorter the IMCS flex tend to get softer. My assumption is that the smaller bottom section would make the mast combo more Constant Curve biased and the smaller top section would make it more Flex top biased. However, since this is an 'indexed' mast system, I am not totally sure. I may have to do an IMCS test on some combo's to find out.
30th December 2007, 04:50 AM
I have a 5.3 Severne blade and it rigs beautifully on a 430 (PWX) RDM. It has an adjustable head strap that is easy to adjust. The top does not stick out very much at all.
I have heard Derek Rijff of Windsport magazine say that a 400/430 combo mast is an excellent travel mast (to keep travel weight down). So, it can't be that bad. But, if I had a choice, I would pick one that has the correct bend. I would rig the 430.
30th December 2007, 06:15 AM
Sorry, but I have no sailing experience on Severne.On this sail the 430 may be the way to go, I say try it both ways, AC/DC !!
Derek on the other hand is very, make that VERY informative and can be found at Delta Windsurfing , Rio Vista , California. lottering.... I think is the phrase they use....
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