Old 20th July 2011, 02:13 PM   #1
Farlo
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Default Wishbone broken

Hi everybody,
The other day my wishbone broke suddenly when I was nicely powered up with 7.8 in some 15 knots. Water was rather flat so no particular shock that I can remember. It is a Nautix aluminium boom that I've been using for about seven years, mostly freeracing with sails bigger than 6. The inner tube (protruding from the head) is cut without signs of previous damage or rust. Can it be just stress and strain? I wonder because I'm relatively light (67 Kg) so I can't load it tremendously. Did any of you experience a similar thing?
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Old 20th July 2011, 05:42 PM   #2
BelSkorpio
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Me and my son have been breaking alu wishbones like it's going out of style.
Most of the times it's close to the head or the head itself.
I guess that the catapults of my son have something to do with it.
Also after a few years, most of the alu wishbones tend to loose their stiffness.
For me, the wishbone is the biggest consumable.
I don't think I have a wishbone of more than 3 years.
Don't know if the carbon wishbones are better, but for the price of 1 you can buy 3 alu's.
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Last edited by BelSkorpio; 20th July 2011 at 10:27 PM.
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Old 20th July 2011, 07:18 PM   #3
Farlo
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OK, I must have been lucky then because it is the first I break in 25 years. I will look for a more robust one, maybe a second hand Nautix carbon as they have very good reputation. Any other brand you can suggest?
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Old 20th July 2011, 10:41 PM   #4
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Quote:
Originally Posted by Farlo View Post
OK, I must have been lucky then because it is the first I break in 25 years. I will look for a more robust one, maybe a second hand Nautix carbon as they have very good reputation. Any other brand you can suggest?
from what I understand aluminum booms have 2 durability issue, salt corrosion and metal fatigue,
so sooner or latter they do break under usage and generally cannot be repaired.
Carbon doesn't have either problem, but there could be production defects like dry carbon, epoxy not penetrating all the way thru, etc.. good thing about carbon booms, you can repair them, and repair done
correctly will be better than original, so you can use them indefinitely. I hear good things about Maui sails
booms, North, NP and Chinook have nice carbon booms too. I see carbon boom as an investment,
cost more but over the years it pay off: better, lighter,stiffer, stronger and it lasts.
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Old 24th July 2011, 02:41 PM   #5
Farlo
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Thank you for the advice. There are a few second hand carbon booms in my shop. There is also a Nautix NXtrem with alumin tubes in the front (ergal) and carbon tail. It is the last one as they just discontinued this model in 2011. Have you heard about or tried such combination? I'm afraid it may break because of stiffness difference.
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Old 25th July 2011, 09:27 PM   #6
Ken
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Aluminum and carbon together oxidize. If it's in the head, it's a really bad idea, but a carbon tail in aluminum tubes? Not sure. The original Gulf Tech booms had a carbon body and aluminum tails, but they also transitioned away to all carbon. I think the stiffness is generally considered to be a boom body issue and not a tail issue, so carbon tails don't sound like a worthwhile idea to me.

In time carbon fatigue will surface. I have had two 100% carbon booms break at the head, but only after several years of use. On the other hand, carbon will most likely last much longer than aluminum.

And if you consider that you could possibly replace your aluminum booms every other year and spend less money than replacing your carbon booms once every 6-8 years, aluminum doesn't sound like a bad idea, especially if you are a fresh water sailor and use the booms on medium to small sails.
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Old 26th July 2011, 02:46 PM   #7
Farlo
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Thank you Ken, my biggest sail is 7.8 so I'd rather take a good aluminium boom, unless I find a used carbon at the same price but I doubt it. Maybe the difference is not that sensible for lightweight sailors with medium sails.
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Old 26th July 2011, 04:48 PM   #8
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heard of plenty of masts breaking, but booms ??
i am surprised
my aluminum and carbon booms have never had issues
windsurfing about 15 years, last three(3) shortboarding

if you know your boom is good for 2 seasons, should you just automatically replace it ??
or have a spare??

my concern now is modern sails
people are telling me your most used sails need replacement every 3 to 4 years
on the islands near the tropics i hear they replace them EVERY year
(they often stay rigged all day, etc)

my "modern" sail has seen about 2 full summer seasons and about 40 outings
the monofilm is starting to look grey and the creases sad
the stitching looks bad on one batten to sleeve joint
some people say ride it to the end with some repairs as needed - others say replace it

what say you ??
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Old 27th July 2011, 12:21 AM   #9
Jean-Marc
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Quote:
Originally Posted by Ken View Post
I think the stiffness is generally considered to be a boom body issue and not a tail issue, so carbon tails don't sound like a worthwhile idea to me.
Wrong. A carbon tail inserted into an aluminum boom stiffens up a lot more the entire boom as compared to that with an aluminum tail. The carbon tail does play a key role in boom stiffness.

Quote:
In time carbon fatigue will surface. I have had two 100% carbon booms break at the head, but only after several years of use.
True. My North Sails racing 220-260 carbon boom lasted 5 years before breaking at the junction between the head and the body tubing.

Quote:
On the other hand, carbon will most likely last much longer than aluminum.
Quite the opposite for me. An all aluminum North Sails boom lasted 15 years before snapping at the junction between the head and the body tubing.

Quote:
And if you consider that you could possibly replace your aluminum booms every other year and spend less money than replacing your carbon booms once every 6-8 years, aluminum doesn't sound like a bad idea, especially if you are a fresh water sailor and use the booms on medium to small sails.
True for boom less than 2 m long and if you're not a heavy weight racer. Otherwise, a carbon boom is stiffer than an aluminum boom of the same lenght. The german Surf magazine has tested 24 all-/hybrid-aluminum and 7 all-carbon booms in their August 2011 issue (*). Lab results have shown that carbon booms are 2x to 3x stiffer than aluminum booms : compare stiffness value of 60-70 N/mm of deflection when a weight of 40 kg is hanging at the middle of a carbon boom with that value of 20-30 N/mm of deflection obtained with an aluminum boom under the same conditions. The Severne Enigma carbon boom and the North Sails Platinum carbon boom are the 2 stiffest booms of the test.

Cheers !

JM

(*): http://www.surf-magazin.de/service/a.../surf-82011-2/

Last edited by Jean-Marc; 27th July 2011 at 12:37 AM.
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Old 27th July 2011, 01:13 AM   #10
kvda
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I do have two Neilpryde carbon booms (matrix 2000, 200-248 and 220-268); the're about 7 years in use and stil ok. 7 years for a Nautix alu boom is very good.

@JeanMarc: That test in the German Surf Magazine also showed that a carbon end in a aluminium boom doesn't make the boom stiffer, but it's much more expensive.
check the difference between the NP X3 and X6:
NP X3 € 230/ 27 / 22
NP X6 hybrid € 449/ 28 / 23
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