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manuel
Joined: 08 Oct 2007 Posts: 1158
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Posted: Tue Oct 20, 2015 10:56 am Post subject: |
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bred2shred wrote: | I wouldn't be concerned about the impact on mast bend up there. What I would be worried about are 1) the fit of the luff sleeve around the now much larger diameter mast tip and 2) sand migrating into the tip extension joint and causing the tip to get stuck on the mast. |
1) For sure that can be a problem on modern RDM-only sails. The sleeve was cut out from roughly the mid-point of a top mast section.
2) Good point, I love fresh water and grass rigging areas, no sand, no corrosion, but I don't have any of this here, only warm salty air and lots of sand! My masts don't get stuck here though, but my boom extensions yes! So I'll be sure to add electrical tape to both junctions. There's a cap on the tip and a cap inside the top mast section. _________________ *NEW* - Manu's Windsurfing Blog, The STORE! |
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U2U2U2
Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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manuel
Joined: 08 Oct 2007 Posts: 1158
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Posted: Thu Nov 05, 2015 11:06 am Post subject: |
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The sail rigged without issues with no perceptible difference, the extension works like a longer vario top cap.
On a more modern sail design, it did seem that there was enough room for the thickened mast tip to fit (I can shove the vario strap inside the luff sleeve beside the mast) although I didn't try, it might be manufacturer specific.
The key is to make sure that everything is snug and that there's no play anywhere. I didn't end up trying on the water as I purchased a 4.5 instead! It's such a short extension anyway that I doubt performance would be affected in any way.
My 5.3 Manic luff length is 426cm so I might try it on there although I do trust my Streamlined extension at near top setting. _________________ *NEW* - Manu's Windsurfing Blog, The STORE! |
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dllee
Joined: 03 Jul 2009 Posts: 5328 Location: East Bay
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Posted: Thu Nov 05, 2015 5:55 pm Post subject: |
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I used a homemade 80% carbon PX top for over 7 years, with a one foot extension later cut down to 9".
The collar epoxied to the mast was 4" for lots of holding power, while the exposed tip of the top was 5" for lots of overlap and safety from breakage.
Funny thing. When you cut a tip, the cut part becomes BIGGER in diameter than it was before the cut. Lucky epoxy resin goes there to take up the space. |
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outhaul
Joined: 27 Sep 2011 Posts: 254
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Posted: Fri Nov 06, 2015 10:36 am Post subject: |
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What's wrong with 26-28cm of base extension?
It's not uncommon even when using the sail's own mast line to specify exactly that.
A quick look at Ezzy specs shows several sails calling for 25-28cm of base extension.
I don't understand the issue here. |
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manuel
Joined: 08 Oct 2007 Posts: 1158
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Posted: Fri Nov 13, 2015 2:04 am Post subject: |
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It's not a worry unless sailing waves. Extensions near their max setting tend to bend (alu) or break (carbon) more easily. Sinking the sail helps save the sail and mast, however the leverage against the extension area cannot be avoided when pulled under. _________________ *NEW* - Manu's Windsurfing Blog, The STORE!
Last edited by manuel on Fri Nov 13, 2015 1:56 pm; edited 1 time in total |
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dllee
Joined: 03 Jul 2009 Posts: 5328 Location: East Bay
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Posted: Fri Nov 13, 2015 12:59 pm Post subject: |
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When you use 30cm of base extension, and you're short or prefer low booms, you're basically placing your booms right where the reinforcement ends on the mast, so you potentially cause a risk of breakage between the reinforcing glass and the non reinforced mast. This has happenned a lot of times in the past, known only to the industry or the shop employees who have to deal with the problem. |
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swchandler
Joined: 08 Nov 1993 Posts: 10588
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Posted: Fri Nov 13, 2015 2:15 pm Post subject: |
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As long as you have the required 5-6 inches of the extension in the mast, there is no real worry of breaking the mast at its base. In 30 years of windsurfing, I've never broken a mast at the base, and I've often used my extensions on their top most position. Also, I will say that I've never broken or bent any extensions using them at full extension, and I like a bit more downhaul than most.
That said, using a lot of base extension can affect the bend curve and how it works in the sail, particularly if you are using a softer shorter mast. For example, if you want to use a 430 mast in a sail normally spec'd for a 460, the upper part of the sail will have a much softer leech with the correct range of downhaul. However, it can work very well if you are a lighter sailor. I did it for years with a number of 7.0 sails, and I really liked the setup.
Lastly, LeeD is right about extending a mast and attaching a boom beyond its reinforcement. That's the biggest risk one faces about using king-sized extensions over 30cms. |
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outhaul
Joined: 27 Sep 2011 Posts: 254
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Posted: Mon Nov 16, 2015 11:43 am Post subject: |
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swchandler wrote: |
Lastly, LeeD is right about extending a mast and attaching a boom beyond its reinforcement. That's the biggest risk one faces about using king-sized extensions over 30cms. |
Great point, something I haven't had to worry about but it makes sense. |
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dllee
Joined: 03 Jul 2009 Posts: 5328 Location: East Bay
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Posted: Mon Nov 16, 2015 7:25 pm Post subject: |
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I"m sorta light in weight, so mostly like the idea of using a softer mast on most of my sails.
Extending the top of a 430 to around 465 allow me to use the small diameter tip section for more flex, while keeping the boom reinforcement on the mast away from transition wrappings on the mast.
While that also flattens the belly of most of the sails, that's fine for lightweights who are good at pumping onto a plane, and who generally ride floaty boards (90+ liters for sails bigger than 6 meters).
It seems even the old aluminum tip extenders work to soften the mast flex on my bigger sails, and yes, the tip extensions don't flex at all, but they do give more leverage for downhaul to bend the mast. |
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