PDA

View Full Version : Mast breakage


John Kemsley
9th May 2008, 12:51 PM
Just broke my North Sting 490, it was right where the bottom cam was. Nn investigation i discovered on of my cam rollers had become loose one side and one was not at the correct angle. I believe that this "point loaded" the mast, leading to the breakage.

Check your cams, or you will end up like I did.

Roger
9th May 2008, 07:40 PM
Hi John,
How much above the top of your extension is this can located.
I've seen a few masts break where a tall extension was used and the lowest
cam and the top of the extension were about the same height from the bottom of the mast.
The mast then gets "point loaded" on both the inside (the top of the mast base) and the outside (the cam).
The Sting was a 50-75% Mast, right?
Was there a groove in the mast where the misaligned cam was rubbing?
Hope this helps,

steveC
10th May 2008, 12:54 AM
If one uses cambered sails, it's a good idea to inspect the mast often for signs of wear caused by cambers. If you catch a wear problem early, you can often make camber and batten adjustments or implement some lubrication strategies to help preclude mast breakage.

John Kemsley
10th May 2008, 09:38 AM
Roger - It was a 30% mast - tough as.... and Cam was nowhere near top of Extension and there was no sign of wear, I think roller had popped off one side last time i derigged - I never checked cam when I rigged, downhauled sail (fully) and as i checked rotation - bang - mast went.

Roger
10th May 2008, 08:48 PM
Hi John,
Well, it was an older mast, so I guess it just got to the end of it's life cycle.
Unusual for a 30%. Most of them are reinforced from the base to the boom
clamping area.
How the heck did you get used to such a heavy 490 cm mast.
I hope you are planning to replace it wth at least a 75% carbon mast.
Should save several pounds in weight.
If sure you will notice the difference immediately and you will like it I'm pretty
sure.
Hope this helps,

John Kemsley
12th May 2008, 05:35 PM
Hi Roger - hope your feeling well - You get used to what you can afford. I also use alloy booms. But the good news is lost 3kg in weight so have offset weight of rig lol

windsurferdagg
13th May 2008, 08:52 PM
I will agree with you there John. Sailors on a budget end up with heavy kit. I also have a 30% 490 and a chinook comp slalom boom. Even on a 7.5 the setup is so blagh. I can get going and put the boom higher and the boom gets all floppy! Pumping? Forget about it. Thats why I am selling the big kit. Nothing bigger than a 6.5 now.