Thread: Wishbone broken
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Old 27th July 2011, 12:21 AM   #9
Jean-Marc
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Join Date: Aug 2006
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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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