The only place silicone should be used on a boat is in the boat babes hooters. If the insert is black, do it on a real hot sunny day after its been laying out in the sun for a while. I used 5200 as well when I replaced mine. I also used screws and fender washers and nylock nuts for the whole thing. What a pain in the behind but much stronger now.

Griff,

Although it does sound like a pain in the ass, I really did notice a difference after I upgraded the rub rail in this manner.

Strength is not really an issue on my boat. The deck on my Pantera is screwed to the hull from the outside and glassed together from the inside. The only thing the rubrail screws do is hold the rubrail on. They are only 1 1/4" screws.
I see your point about the strength issue on boats that are not built this way.

Pantera's kick ass. That is a great boat you have there.

My boat is screwed together and glassed from the inside out as well. The screws from my original rub rail though started to loosen up after 10 years, thus the tighter feel after the upgrade...

it wasn't hard,just use a rubber mallet & take your time. i gave up trying to match the plastic rubrail & switched to stainless.