[Douglas]

Currently, I am in process of installing bronze Muray halliard winches on my aluminum mast, but using Delrin plastic pads between the two, and using SS flathead machine screws, to secure them.

I am not sure just why you decide to use rivnuts, and not just thread the mast wall for your fasteners.

I guess that you are familiar with Heli-Coils, as if you had to redrill the fastener holes to a better angle, then insert the Heli-Coil to bring the thread size back to your original size ?

Nigel Calder's book says he doesn't like welding on the aluminum mast tube especially when that welding goes half way around the mast, like at a spreader base.

It is good that you are asking questions when you are not sure, and I have always liked Brion's words, "build in a reserve of neglect, when ever you can" ,,,, there is great wisdom in his words.

Douglas