Thanks for posting the
pictures – that is an interesting solution for holes that have gotten enlarged
by repeated drilling out of old rivets.
It looks like you place
the threaded backing plates vertically so they each capture two of the Socket
Cap Screws up and down, but how do you hold the four backing plates in place
inside the furling extrusion when you lower it into the socket? Do you
use an adhesive of some type? Also, are the backing plates curved to
match the curvature of the furling extrusion?
That would be good for load distribution as well as giving a larger surface
I cannot tell from the
picture, but are the backing plates made of stainless steel like the A4-70 Cap
Screws? This assembly gets a lot of sea water on it and corrosion between the stainless
steel and the aluminum is concerning. Since those are just conventional Socket
Cap Screws (aka Allen Head Screws), they are readily available in Aluminum
which, combined with an aluminum backing plate, might be a good choice to avoid
corrosion and retain the "weak link" safety feature of the rivets.
(If you want more strength you might go up from 6mm to 7mm AL, rather than the
hugely strong SS bolts.)
One could also use bolts
with conventional hex heads that do not stick out so far as the cap screws do,
thus avoiding any snagging issues.
As for the issue of the
cap screws loosening, I should think either a conventional lock washer (split
washer) and/or using some Loctite on the threads when assembling would do
Craig Briggs, SN#68