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jfeehan
Joined: 27 Jul 1998 Posts: 156
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Posted: Thu Oct 19, 2017 9:06 am Post subject: |
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U2U2U2 wrote: | NOVAAN wrote: | Do not remove the collar and set the mast all the way down. You will break your mast |
I've done this a few times never a problem, never heard of one |
i've wondered about this as well.
it certainly seems as though the loading is not as intended, but i think it would take a lot to split a skinny mast |
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U2U2U2
Joined: 06 Jul 2001 Posts: 5467 Location: Shipsterns Bluff, Tasmania. Colorado
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NOVAAN
Joined: 28 Sep 1994 Posts: 1555
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Posted: Thu Oct 19, 2017 9:22 am Post subject: |
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The cone shape of the extension has a wedging effect on the bottom of the mast. It will eventually split the mast. I did it years ago with a standard mast.
Might be better with a rdm mast but why take a chance. Mast expensive proper extension cheap. |
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jfeehan
Joined: 27 Jul 1998 Posts: 156
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Posted: Thu Oct 19, 2017 9:38 am Post subject: |
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NOVAAN wrote: | The cone shape of the extension has a wedging effect on the bottom of the mast. It will eventually split the mast. I did it years ago with a standard mast.
Might be better with a rdm mast but why take a chance. Mast expensive proper extension cheap. |
exactly - it's the tapering of the extension that is potentially problematic. it will impart a circumferential stress that the mast is not designed to withstand.
it might not be enough to matter.., or it might be... |
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bred2shred
Joined: 02 May 2000 Posts: 989 Location: Jersey Shore
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Posted: Thu Oct 19, 2017 10:02 am Post subject: |
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It's been discussed before.
Removing the collar is certainly not how the extension was intended to be used and likely puts undue "hoop" stress on the bottom of the mast as the extension tries to wedge itself into the mast. I suspect the mast could also start to wear into the base extension since the load is not being dispersed over the entire bottom surface of the mast and instead only right along its inside edge.
There's no real way of knowing whether or not the mast will break (until it happens). But this is a risky move if the only benefit is to shave off one or two centimeters of mast height.
If you're going to do this, you might want to consider wrapping several layers of half inch or one inch wide uni-directional carbon around the bottom of your mast to increase the hoop strength and prevent splitting. Also take a piece of 100 grit sandpaper and knock off any sharp edge on the inside circumfrence of the bottom of the mast to make it nice and "friendly" where it contacts the base extension.
sm |
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dllee
Joined: 03 Jul 2009 Posts: 5330 Location: East Bay
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Posted: Thu Oct 19, 2017 11:29 am Post subject: |
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All this for 1.25 inches, on a wave sail? |
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manuel
Joined: 08 Oct 2007 Posts: 1158
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techno900
Joined: 28 Mar 2001 Posts: 4184
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Posted: Thu Oct 19, 2017 2:19 pm Post subject: |
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As zirtaeb said.......... If racing slalom, then closing the gap 1.5 inches may be a good idea, on freeride or wave set ups, little if any advantage other than it may allow the perfectionist to feel better. |
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dhmark
Joined: 04 Sep 2007 Posts: 376
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Posted: Thu Oct 19, 2017 3:47 pm Post subject: |
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Perfectionist wouldn't have this problem because a sail wouldn't be designed for a mast with only 6 cm extension, would be designed for the next smaller size mast. |
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isobars
Joined: 12 Dec 1999 Posts: 20946
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Posted: Thu Oct 19, 2017 5:37 pm Post subject: |
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1. The 6.9 has a 486 luff according to Goya.
2. Why would anyone make a sail with a non-adjustable mast cap?
3. Do NOT remove the collar, for reasons stated. Log splitters are wedge shaped for a reason.
Each chop impact or hop landing is another hammer blow to a base without its collar ... aka a mast splitter. One second, it's fine; the next bump or chop hop the mast is destroyed.
Do I feel lucky? Well, do ya, punk?/
4. Nobody not competing for a World Speed Record gives a damn about an inch or three of gap between the sail and the deck. That inch or three gap will matter infinitely less than an improperly tuned sail, and matters only when the entire foot of your sail is rubbing the deck in a broad, pure speed run on flat, flat water with a race sail on a speed board with the reigning world speed champ on your tail.
5. When's the last time THAT happened?
6. 5. US base Chinook skinny aluminum bases have a 10.7 cm/4.2" minimum extension. |
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