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Sail recommends longer mast than the luff
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aleko.petkov



Joined: 10 Sep 2014
Posts: 6

PostPosted: Sat Oct 11, 2014 11:13 pm    Post subject: Sail recommends longer mast than the luff Reply with quote

My sail, an HiFly X-Ride 5.5, has a luff of 447, but recommends a 460 mast. It is rigged on a 430 mast, with a 34cm extension. This combination was chosen by the windsurfing shop where I bought the whole setup (board, mast, sail, boom).

Why does the sail recommend a longer mast than the luff? Is that the maximum mast length it would fit, i.e. the limit of the strap adjustment?
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cgoudie1



Joined: 10 Apr 2006
Posts: 1274
Location: Killer Sturgeon Cove

PostPosted: Sun Oct 12, 2014 12:42 am    Post subject: Re: Sail recommends longer mast than the luff Reply with quote

Nope, it's more likely the amount of mast length the sail needs for the
geometry to bend it appropriately, but on that sail, a 430 with 30cm of
extension should work fine, if you're not at the maximum on the extension.

Have you measured the actual luff length? It's not something you should
get hung-up on, but that might be interesting. It might also be interesting
to know who the real manufacturer of the sail is.

-Craig

aleko.petkov wrote:
My sail, an HiFly X-Ride 5.5, has a luff of 447, but recommends a 460 mast. It is rigged on a 430 mast, with a 34cm extension. This combination was chosen by the windsurfing shop where I bought the whole setup (board, mast, sail, boom).

Why does the sail recommend a longer mast than the luff? Is that the maximum mast length it would fit, i.e. the limit of the strap adjustment?
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manuel



Joined: 08 Oct 2007
Posts: 148

PostPosted: Sun Oct 12, 2014 1:27 am    Post subject: Reply with quote

The 460 will give a touch more stiffness while the 430 will soften the sail. Lighter guys tend to like softer masts and bigger guys stiffer masts. If you notice a slight lack of power when a gust hits, try the longer mast.

Only vario top sails (like yours) can take longer masts, fixed ones cannot.
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joethewindsufa



Joined: 10 Oct 2010
Posts: 188
Location: Montréal

PostPosted: Sun Oct 12, 2014 6:47 am    Post subject: Reply with quote

http://www.the-house.com/hfmotcxr558zz-windsurfing-packages.html

clearly shows a luff of 447 and an included Chinook mast of 460

for the OP this is the first time I have heard of putting max vario-head + extension on the bottom
usually one does one or the other
like 430 mast + 17.5 cm extension with NO vario-head
or 460 mast with vario-head extended

has the OP tried the 430 mast with 17 cm+ extension and NO vario head ?
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dennis_c



Joined: 05 May 1998
Posts: 652
Location: Rio

PostPosted: Sun Oct 12, 2014 10:30 am    Post subject: Reply with quote

X-Rides appear to be from Gaastra, with some really long mast lengths for sails designed this century. http://www.totaloption.com/search/product.asp?product=35
Dealer probably did you a favor selling you the 430, as you will not need a 460 mast until you get a 7.5 or larger, and you will probably want high carbon content for that.
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aleko.petkov



Joined: 10 Sep 2014
Posts: 6

PostPosted: Sun Oct 12, 2014 2:06 pm    Post subject: Reply with quote

joethewindsufa - I haven't tried that combination. Wouldn't that move the mast curvature off from where it should be?
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aleko.petkov



Joined: 10 Sep 2014
Posts: 6

PostPosted: Sun Oct 12, 2014 2:25 pm    Post subject: Reply with quote

cgoudie1 - Ah, it's the curvature... That makes sense. On the other hand, I would think a 460 mast with no extension bends differently from a 430 with 30cm of extension, no?

I have not measured the luff, but I did measure the mast, and it is definitely 430cm. The sail is made by Gaastra.

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adywind



Joined: 08 Jan 2012
Posts: 222

PostPosted: Sun Oct 12, 2014 2:29 pm    Post subject: Reply with quote

Sailworks sails do this a LOT and I hate this about them. It just ruins the whole aesthetic of the rig. I have few of they're Retros and Revos and for me /on the shorter and lighter side/ the sails feel and look better with shorter mast and longer extension. Experiment and find what works for you regardless of what the manufacturer says. I also use skinny masts only ,even on my 9.0-contrary the recommendations -sorry but I like it this way Smile
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swchandler



Joined: 08 Nov 1993
Posts: 5881

PostPosted: Sun Oct 12, 2014 2:53 pm    Post subject: Reply with quote

manuel is spot on. Given a comparison between 430 and 460 masts of the same brand, the bend will be the same but the stiffness will vary, with the latter being the stiffest of the two. A 430 has a usual stiffness of 21 IMCS, whereas a 460 is usually around 25 IMCS.

Normally these days, there is a tendency for sail brands to recommend buying masts where the top isn't extended, and all the adjustment in done with the base extension. Still though, even today, sail manufacturers will incorporate an adjustable head as a feature in smaller sail sizes up to 6.0 to 6.5 to give the customer some overall flexibility. It's important to remember that in the past, there wasn't so much focus on having multiple mast sizes. Back in the 80s and early 90s most folks would have a 14 footer for high wind sails and a 15 footer for medium to light wind sails. These days with all the emphasis on a loose leech, it's pretty hard to get there using small sails on larger stiffer masts.
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DanWeiss



Joined: 24 Jun 2008
Posts: 1958
Location: Connecticut, USA

PostPosted: Mon Oct 13, 2014 11:15 am    Post subject: Reply with quote

swchandler wrote:
SNIP Given a comparison between 430 and 460 masts of the same brand, the bend will be the same but the stiffness will vary, with the latter being the stiffest of the two. A 430 has a usual stiffness of 21 IMCS, whereas a 460 is usually around 25 IMCS.

SNIP


For clarification, while the bend shape will be scaled as a percentage of overall length, the location of maximum bend in real numbers is different for masts of different length.

Simply adding 30 cm to the bottom of a 430 will not locate the maximum bend at the same place as the 460 simply because the location of 430's maximum bend is less than 30cm lower than the 460. Adding 30cm to a 430 will then place the max bend higher than if you simply used a 460.

Does this matter? Sort of, and more so when comparing a 370 to a 400 rather than a 460 to a 490, for example. It remains true that the most noticeable effect is caused by the different stiffnesses.

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