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Who uses a tall extension?
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rtz



Joined: 31 Oct 2010
Posts: 256
Location: Oklahoma City

PostPosted: Sat Aug 10, 2019 3:20 am    Post subject: Who uses a tall extension? Reply with quote

Are there any sails out there that call for that much extension? What is the purpose of such a long extension?

What is the setup you use one with that uses the additional extension?
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dllee



Joined: 03 Jul 2009
Posts: 4604
Location: East Bay

PostPosted: Sat Aug 10, 2019 8:45 am    Post subject: Reply with quote

Makes the total mast softer.
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manuel



Joined: 08 Oct 2007
Posts: 991

PostPosted: Sat Aug 10, 2019 9:13 am    Post subject: Reply with quote

Any time the luff length is just a touch over a mast size. So 398/405 requires a 370 mast with 28 to 35cm extension or a 370 bottom with 400 top.

I decided to salvage a broken mast top and create a mast extension tip which I've been using instead of running long extension. It gives the mast a bit more flex top and I feel safer running a not so stretched extension whether either are important is debatable Very Happy !

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cgoudie1



Joined: 10 Apr 2006
Posts: 2275
Location: Killer Sturgeon Cove

PostPosted: Sat Aug 10, 2019 9:30 am    Post subject: Re: Who uses a tall extension? Reply with quote

I'm running a Northwave 6.2 with a lot of extension and a 430.
That gets the reinforced section of the mast up by where I typically run my boom.
I also prefer the feel (which seems more pumpable and i'm usually
looking for as much planning power as I can get when on a 6.2)
to a 460 with almost no extension.

There's your purpose,

-Craig

p.s. If you're a minimalist, some sail quivers would reduce your
number of masts with long extension use. I personally like being able
to rig each size up and down next to the other, but I'm more of a maximalist. ;*)

rtz wrote:
Are there any sails out there that call for that much extension? What is the purpose of such a long extension?

What is the setup you use one with that uses the additional extension?
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U2U2U2



Joined: 06 Jul 2001
Posts: 5073
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Sat Aug 10, 2019 9:54 am    Post subject: Reply with quote

According to Pertermans mast article at

Www.peterman.dk/Windsurf-mast-article-gb01.htm

All masts keep (approx) their bend curves when they are extended.
All masts become a little stiffer (according to imcs standard) when they are extended.
Hard top become relatively 2-3% less stiffer.
Flex top masts become relatively most stiffer 6-7%.
Constant curve masts become stiffened up between hard top and flex top , around 3-6%.

As you can see itís a murky science, one first need to determine what the mast curve is.
Then forget about it.
The use of tall extensions to the longest length brings up the possibility of breaking or bending it. To me this is much more of an area of concern.

The use of a long extension, by the sailmakers POV , is use a 430 mast where the luff length is closer to a 460 mast length. The designers often scale down a sail size and this occurs. Very common. If the sail has a vario head strap, then a 460, could make more sense.

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grantmac017



Joined: 04 Aug 2016
Posts: 838

PostPosted: Sat Aug 10, 2019 11:27 am    Post subject: Reply with quote

Are we talking RDM or SDM masts? Small sizes (<430) or large ones (>460)?

I have a North Warp 11.9 that rigs on a 550 with a fixed 50cm extention (haven't rigged it in years, sold the mast). Clearly North wasn't afraid of a long extension.
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GURGLETROUSERS



Joined: 30 Dec 2009
Posts: 2330

PostPosted: Sun Aug 11, 2019 2:04 am    Post subject: Reply with quote

Agree with U2 in the worry of extra strain and possible breakage of using long extensions, especially in surf conditions.

My current North Session 6.0 sail is shaped and cut for a 430 mast and 30 cm extension, yet you can't use a 460 mast with its fixed head, because the bottom of the sail then sticks up too far above the base. I mean come on. All they had to do was fit an adjustable top cap to allow us retards to use the bigger mast.

I've had loads of 6.0 sails over the years which didn't need long extensions, yet managed to work very well, but hey, who knew we were so handicapped in the past, and we were sacrificing such wonderful efficiency? I can't imagine why I ever had such a big smile on my face.

P.S. I've never tried this 6.0 North with a 430 RDM mast and long RDM extension. I can't help but think that would be courting snapping in surf wipe outs. RDM masts may be tough, but long RDM extensions?? Besides, I prefer SDM masts for sails of 6.0 and above for general feel and power.
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manuel



Joined: 08 Oct 2007
Posts: 991

PostPosted: Sun Aug 11, 2019 8:07 am    Post subject: Reply with quote

Forgot... A friend of mine uses a long extension so he can use a shorter and therefore softer mast. He's a light weight. Uses it in the surf yes. Believe long Chinook carbon.
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U2U2U2



Joined: 06 Jul 2001
Posts: 5073
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Sun Aug 11, 2019 8:41 am    Post subject: Reply with quote

http://peterman.dk/


Correct link

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GURGLETROUSERS



Joined: 30 Dec 2009
Posts: 2330

PostPosted: Mon Aug 12, 2019 2:27 am    Post subject: Reply with quote

Thanks U2, an interesting find.

I must admit to being baffled by this trend for longer extensions in shorter masts, when a longer mast and short extension has always been the answer. Does a problem really exist?

When sails have reached the end of their working life, and need replacing, I bung them up in the attic. That has the advantage that, with over 25 old but still working sails, I can fish any back out to compare directly with the new replacement.

This thread, and the justification for this 'new' long extension short mast concept, is a case in point, so yesterday, I fished back out a 15 year old once favourite 6.0 sail which sets perfectly on my middle of the road 460 Tushingham C 40 mast, and along with the new North Session 6.0 sail set on my Tushingham C 40 430 mast with 30 cm extension, tried both, turn about, on my old Saxo (its 21st birthday fling) in average gusty 6.0 winds and sea. Less than perfect conditions, but a decent challenge to keep on the plane.

In short, for straight line planing in on/off conditions, no obvious difference. But in turning and gybing there was. It may be that the old Saxo (long and narrow) was not suited to this modern sail concept, but the pull from high up of the Session sail (it's an intended feature of that sail) clearly upset the feel and balance of the board. Perhaps it would have different had I used my modern Cross 94 board. I will, next time.

In the meantime, this new concept sail is not a favourite, so I may as well alter the top to an adjustable cap fitting and use it with the 460 mast and short extension. I'll see if that makes any difference. (Both masts used were SDM.)
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