The beam is well and truly siliconed in place from way back when it was probably first assembled, so splitting the beam away from the hull really was going to be a major PITA..... and I couldn't see why I needed to disturb it.

That meant I couldn't feed the bolt through the beam and then down the hole that easily.... went with the easy option of bolt up through the timber and thread and nut in the beam.
If in the future I have to drop the beams of then yes I'd put the bolt head inside the alloy beam as you've suggested



As for the traveller track.....
I have a couple of attachment ideas

option 1
The old self tappers stainless screws held quite well over the years but they created a corrosion issue, sure that took ~30years to corrode the anodising away and a slight pitting around the screw hole so it would be safe to say that the screws would last another 10years of trouble free work.... maybe

option 2
rivets....


option 3
tig weld it



then the grey matter started grumbling around and I ended up with a combination that will do for the time being (read I'm low on argon gas and don't have enough left for that amount or tig work )

So I dragged out the trusty old riveter, looked long n hard at the 30mm grip rivets I have, had a gander at the countersunk hole in the track and decided I know exactly why the rivets come loose....

lathe time

Obviously, one needs countersunk pop-rivets if one is going to put them in a countersunk hole because if you use pan head rivets in a countersunk hole then its only the very outer part of the rivet head that is gripping, the actual throat of the rivet is doing diddly-squat and its the throat that does the work and its there where the max strength of a rivet exists !

meanwhile back at the lathe.....
an anvil and a drift has been machined up to suit the pop-rivet, the anvil will form the underside of the pan head into a countersunk shape while the drift will be the forcing point and will also flatten the pan head out flat .....

and hey presto (actually 40mins later), countersunk 30mm pop-rivets are being fitted

I've also put a stainless countersunk nut n bolt assembly at each end for the shock loading factor on that wild gybe

The track has also been rounded off on each end so its now not only sheet snaring free but far more wetsuit friendly aswell

If or when the rivets begin to loosen up then I'll just save time.... clamp it down and tig it in place