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Re: Mast screws. How tight?

Posted: Wed Sep 16, 2020 9:47 am
by Foil
purdyd wrote:
Wed Sep 16, 2020 2:31 am
Another reason to lubricate the threads is to prevent galling. That is binding of the threads.

The reason you want your bolts to be tight is so that the two contacting surfaces are pressed together with sufficient force to keep them from moving or separating.

To do this proper preload on the bolt is needed. A loose bolt is actually bad.

It is best to have them under proper preload.
This for any of us with any sort of engineering background is a dilemma.adding lube to the mast to fuse connection- stainless to stainless- is not a great idea as there are a few problems, grease attracts fine sand particles so you end up with a grinding paste as you tighten up, and washing out and cleaning the threads before or after each session is not that easy, and grease on tools and fingers easily contaminate the wing and mast working surfaces and that can be a stability disaster about to happen, but as above- if you bind the threads(creak them tight :oops: ) then that's not great either
and its just makes me gasp when sometimes after a session I can easily undo my front screw, sometimes by just spinning out with two fingers lightly pinching the upright allen key shaft, and there was no indication when blasting around in the waves there was ever a loose fixing point, crazy!
as for the mast track bolts of stainless into brass, the problems I have seen is that the bolt not being long enough to grip all threads resulting in the main tightening force being applied to the very thin walls on the top small cylinder shaped part of the brass T nut, which just splits it apart when over tightened, or when you run into a sand bank,
check them as I have seen this 3 times with my own eyes over 3 years, so it must be a common issue that is out there right now, I always carry spares which a few of my sailing buddies have borrowed over the years,
same for the mast to fuse 6mm allen head cap screws, they do wear slightly and bend a tiny bit if you bash a sand bar hard, I carry a bag of these as spares and change mine every few months (but I rarely miss a day on the water)