boom failure- this ever happen to anyone else?

[jfeehan]

When mounting stainless hardware on aluminum and carbon, sailboat riggers often use Tefgel to inhibit corrosion.

It forms a barrier between the materials.

I use it on my boat, and it seems to work.

[pacspeed]

Definitely a fastener issue. My Tripleclamp carbon wave lasted 5 years of some of the hardest sailing it could get...Gorge, Ca coast, and Baja, including getting washed in double to triple overhead. Never had even a hint of trouble. BUT: if I had a bad batch of screws...that would be the end of it.

There's nothing inherently wrong with the design...clearly room for improvement, but in this case, I think it's clearly a screw failure. A MIL rated 316 screw should sort it right out.

[richhotdog]

I broke chinook carbon boom at the head/arm intersection just like the first photo. I did it in a overpowered jibe. Chinook never answered my e-mail,but a phone call got me a new arm at a reasonable price quickly. Call them for problems.

[bred2shred]

Reviving an older thread here...

While sailing yesterday, I felt my Chinook triple clamp boom go "ping". When I got back to the beach I looked at the boom head and noticed that one of the nuts was missing. I looked a little closer and realized that three of the four screws that hold on the triple clamp head were broken and the boom arm was being held to the head by the remaining edge of the screw. Damn that would have sucked if it had let go...

My plan going forward is to replace the screws (obviously) and epoxy the arms into the boom head. IMO, it's simply not worth taking the chance that these screws could fail. I recommend anyone with a Chinook triple clamp boom inspect the screws regularly and keep a spare set o screws and nuts handy.

sm

[swchandler]

Are you really sure that you want to use epoxy? Without some structural reenforcement, epoxy has very questionable strength on its own. Moreover, if some other aspect of the triple clamp boom head fails, you might not be able to replace it.

What you might want to investigate is locating some highly spec'd aerospace rated screws instead of the run of the mill SS screws being made in China or elsewhere. Also, you might want to replace the screws at some reasonable intervals to better ensure their integrity.

[nw30]

Buying s.s. screws or bolts with a different type of drive (hex or square) is probably going to give you a higher grade of s.s., as they are not as popular, and probably made in the U.S.
I prefer the sq. drive heads, almost impossible to strip, as well as the sq. bit, great for foot straps and wooden decks as well.

[bred2shred]

[isobars]

After all, the primary obstacle to using adhesives exclusively instead of nuts, bolts, and rivets to fabricate automobiles, skyscrapers, and military and commercial aircraft is habit; it's already very widespread. As soon as the mechanical fastener Luddites retire, mechanical fasteners may all but disappear in large scale production.

[bred2shred]

Screws and other mechanical fasteners will always have their place as a proven, and easily installed/removed means of joining parts. In the case of the Chinook triple clamp, it is most likely just a case where they found a cheap supplier of low quality screws. Yes, some MIL spec 316 machine screws would most likely do the trick. But I'd rather sacrifice the ease of disassembly of the screws for some peace of mind that if the screw does fail, the arm will still be held in the head by the epoxy - belt & suspenders philosiphy.

sm

[MalibuGuru]

No need for epoxy because the mast/outhaul forces are holding the boom together.

This same thing (metal corrosion) has caused my older Chinooks to fall apart. Make sure you find the same shaped nuts that fit in their slots or you will have a problem. Best to just call Chinook and I'm sure they'll set you up with new stainless nuts/bolts.