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Any sailors ?

Any sailors ?

Any sailors ?

(OP)
hi guys,

I'm a big fan of the volvo ocean race. Twice now the mainsail track has failed. This connects the front edge (luff) of the main sail to the mast and so carries a ton of load.

The question ... why bond it on ? (instead of mechanically fastening it) and why put the bond in tension (and not shear) ?

another day in paradise, or is paradise one day closer ?

RE: Any sailors ?

I'd guess that mechanical fasteners would result in moving the failure point to the mast.

These boats are designed for minimum possible weight at very low safety margins.

RE: Any sailors ?

Designing joints in cf structures is always fun. In this case you've got an impedance mismatch between the track, which is a stiff system in its own right, and the underlying mast. If I were bodging it I'd get duct tape and wrap it around the entire mast and track. That is roughly what the correct joint should look like (OK you wouldn't be able to get the sail up and down, that's a secondary issue) . The aircraft industry developed a lot of bad practices when they started using composites, and the silly attitude has persisted as other industries picked composites up. The guy I learned about this from made cf motorbike frames, his metal bits didn't fall off the frames.

What's happening is that the mast is flexing one way, and the track is flexing a different way, and the glued joint is being prised apart.

Cheers

Greg Locock


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RE: Any sailors ?

(OP)
thx guys

@mint,
yes, i know low margins (someone said during AC if you weren't getting occasional failures then you hadn't slimmed down enough). I'd've thought you could design the joint to protect the mast ... if the mast has the highest MS, then the failure will either be the fasteners or the track, probably the track (in segments, as it is now, easy enough to replace).

@greg, so you don't think having the bond work in shear is a good idea ? I agree it'd need to be carefully designed. and i guess it does work well enough as is, just seems odd to have a bond in tension.

another day in paradise, or is paradise one day closer ?

RE: Any sailors ?

I guess the answer to how close can you shave your pencil has now been discovered on Vestas , and I guess the answer was " Too Close."

South Atlantic Ocean, March 30, 2018 - Vestas 11th Hour Racing has dismasted while racing in Leg 7 of the Volvo Ocean Race. The team is safe and reports there is no immediate danger to the crew.
The team reported that the mast broke at 15:59 UTC and Race Control was informed of the situation at 16:15 UTC on Friday afternoon. The crew was forced to cut away the broken mast to avoid damage to the hull. The boat is approximately 100 miles southeast of the Falkland Islands and as of 19:00 UTC was motoring under its own power towards the islands.
At the time of the dismasting, Vestas 11th Hour Racing was sailing in a 25 to 30 knot northerly wind with 3 metre waves. Other boats in the fleet are in the area and have been informed of the situation in order to render assistance if needed.

B.E.

You are judged not by what you know, but by what you can do.

RE: Any sailors ?

Quote (berkshire)

South Atlantic Ocean, March 30, 2018 - Vestas 11th Hour Racing has dismasted while racing in Leg 7 of the Volvo Ocean Race.

Quote (rb1957)

Twice now the mainsail track has failed.
Maybe the track failing is a good thing.

Bill
--------------------
"Why not the best?"
Jimmy Carter

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