I won't mention the brand, but I've owned a 140-190cm Monocoque boom for two years. The mast clamp has given me nothing but headaches. Note: It's got an RDM adaptor, so it can clamp to a SDM or RDM mast. I use it with RDM masts.

The biggest problem (among others) is the clamp slips down, lowering the boom during sailing. Since owning the boom, I have used it with the RDM adaptor, which the clamp slips very badly no matter how tight the clamp is, and scratches the enamel off the mast. I have also used it without the RDM adaptor and with a plastic SDM shim. In this case, it doesn't slip as badly, but does slowly slip down over a period of a few hours. However, if I clamp is ready ready tight, it doesn't slip, but I'm concerned about damaging the mast. Just a couple of questions.

How much clamp pressure can an RDM mast take using a plastic or rubber SDM shim ? (Can I crank the clamp pressure without damaging the mast ?)

Does anyone have any opinions about this product for RDM masts ?:

www.surfsailaustralia.com.au/showProduct/Windsurfing/Boom+Max+Length+Up+To+200cm/tcwave/Chinook+Wave+Triple+Clamp+Alloy+Boom

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Thanks :)

Thats the boom I use, except I have the carbon model.
I use the rubber shim for rdm, and without the shim for sdm.

It never slips ever. (major crashes exempt of course)

With clamping pressure, I clamp it fairly firm, but not crazy tight.
Doubt you would ever crush an rdm no matter how tight you clamp it, a sdm however is much thinner and it is possible you could damage it if you clamp it "gorilla tight"

Hi jn1. Have you tried the rubber rdm shims? Take the rdm adaptor off and use a rdm shim. I have been using the ezzy shims for the past 4 years and they work great. Nice secure fit, much better then the rdm adaptors that come with the booms, from my experience.

I've read that the shims are better for the mast than the adaptors as the shim has a cushioning effect. The snap in adaptors are a bit thin and lack padding.

I really like the triple clamp head (discontinued now I think) on the Chinook booms. I have never hap slipping problems (I use a shim though) and have a really positive operation. Nice stiff boom too.

Agree with RDM shims.

The rubber grips the mast well, I used Ezzy (No Limitz) for ages and never had a slip, now use NP and likewise.

Sadly the new chinook clamps (not the triple clamp) are a little too tall to get the nolimitz shim into. I'm looking at trimming the clamp a bit...

Since owning it, I've tried a rubber Mauisails shim and a rubber Severne shim. Both don't fit. I then got a plastic severne shim (which came with one of my masts last year). This plastic shim has a smaller diameter then my two other shims, and fits perfectly... but because it's plastic, it's probably still not perfect. I'll try sourcing a rubber shim. Hopefully it's diameter compatible.

Thanks all for your advices :)

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jn1 said...

Since owning it, I've tried a rubber Mauisails shim and a rubber Severne shim. Both don't fit. I then got a plastic severne shim (which came with one of my masts last year). This plastic shim has a smaller diameter then my two other shims, and fits perfectly... but because it's plastic, it's probably still not perfect. I'll try sourcing a rubber shim. Hopefully it's diameter compatible.

Thanks all for your advices :)

Put some tape around the mast under the shim this caused more friction than just being against a smooth mast and thus reduces the chance of the boom slipping.

Line the shim with a few lines of black witch (or any rubber/neoprene glue), never slips then and adds more cushioning. Do it diagonally down the shim for maximum contact.

I prefer the built in shims on the chinooks than the supplied shims with my masts as one trapped my finger once when putting it on

Never had a triple clamp slip, and had 3 before I had to renew when I became a team rider. Must confess I preferred the older triple clamp, due to the ease of putting the boom on without faffing with hinges in tight luff tubes with hand eating zips.

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ikw777 said...

Sadly the new chinook clamps (not the triple clamp) are a little too tall to get the nolimitz shim into. I'm looking at trimming the clamp a bit...

Ian, I recently purchased a Chinook boom. I cut the raised lip of the ezzy shim (one end only) and all is good. Shim fits perfectly in the clamp.

Agree with ejmack, use the rubber shim and grind the raised lip off one side and then it fits

ejmack and Zachery: Sweet! That's good to know.

Yep, agree with the rubber shim. I used a fiberspar one for years with a chinook boom. Never slipped.

I also had to grind the end off the shim to get it too fit.