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Mark _australia said..
Anyway I will reserve judgment and wait til they've all had a couple of seasons use - but for now my preliminary thought is I think the joint will wear too much and I will have a lot of work to do tightening them again for customers. Like the GoFoil front wing onto fuse that gets loose. Interference fit is not a good idea for composites and when you add sand and salt it makes a wonderful grinding paste. Just look at the wet black goo that develops in your windsurf mast (that the sail rigs on) after one session.
Yeah, now looking at how the joint actually works i think you're right. Dyneema stretches with time and strain. Not sure how long that chamfer join will last without the tension. Things will get sloppy, probably sooner rather than later.
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airsail said..Subsonic said..
Yep, should be all good, but why move from m8 to m6? There is no good reason.
Actually there is a good reason, 4 x M6 screws are more than strong enough for mast mounting, many brands have been using it for years, never heard of a bolt failure. Smaller screws allow for more "meat" to be left in the mast plate, the slots are narrower which results in a stronger, lighter joint.
as to using m6 rather than m8, m6 bolts have definitely been known to snap under load in deep tuttle foil boxes. Treated the right way, tensioned correctly and swapped out for new frequently enough, they tend to do "ok". The main issues with them is the bolt itself doesn't have enough meat to survive a shock load if not tensioned correctly. The thread on them is also much finer than an m8 thread, which means they are more prone to stripping. If you over tension it you fatigue the metal very easily, which can lead to failure. Fair enough to say two (rear) bolts will cope with the loads much better than one, it probably will. But you are swapping out the better scenario of over engineering for no reason what so ever. If changing down to m6 gives the mast plate more meat, then mast plates have been under engineered on those foils made for m8.