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One thing that could affect the wear rate of the extrusion attachment hole is the bolt itself. Check to be sure that there are no threads in contact with the surfaces that bear the torque stresses. The smooth part of the bolt should in other words be long enough to allow tightening when bottomed. It may be necessary to have a custom bolt made to attain the correct length. One can think of the threads of the bolt as a sort of a file that will chew out a bit of aluminum each time the joint is loaded.
The internal bushing sounds like an interesting idea.
On Jan 28, 2020, at 12:10 AM, Mike Longcor (SV Trilogy) <svtrilogy53@...
If there is noticeable play back and forth between the main foil and the bolt, is there anything one can do to slow down or minimize the metal-on-metal wear and tear? Perhaps a bushing or sleeve on the bolt would eliminate the gap, but there probably isn't enough space above and below the bolt as all the wear is horizontal.
Waiting until the foil shears itself would probably create some unneeded excitement at sea. Cutting/shortening the foil before it fails seems wasteful. Has anyone tried what Nick has suggested? An internal bushing slid up inside the foil to spread the loads and reduce fatigue seems like a good idea. Or perhaps with proper care the "three lives" provided by design is enough to cover one's lifetime if not the boat's lifetime. If that's the case, would it be advisable to cut my foil preemptively?
Graham, will you attempt any extra reinforcement when you do your repair?
SV Trilogy - SM23