Hi Roger! I just landed onto this forum recently, and while I have been reading for a while, you get my first post on the forum!
I'm not sure if this has been discussed previously on the forum, but I wanted to drop you a line because I just went through this exercise a few weeks ago with our "new" 1974 Trillium
. I used a small paint
scraper (rasor blade type) to delicately peel off the old silicone without scratching the gelcoat. I then used acetone to clean out the leftover bits using a brass toothbrush-like paint
scraper, used a dremel with a metal polishing bit to bring back the original shine to the entire aluminium trim, and finished it off with a Never-Dull type metal polish. I am very happy with the result, and there was no damage to the gelcoat at all.
One comment: If you drilled through the whole fiberglass wall to install the new rivets, you should really make sure that you seal it off properly to prevent leaks
. Silicone doesn't adhere well to fiberglass so you should pick an appropriate caulk, and keep it in check.
My understanding is that the original purpose of the trim was only decorative. There are small rectangular pieces of metal that hold each of the rivets from the inside, and those brackets were originally actually sealed off with a thick layer of fiberglass that covers the entire seam from the inside (to join the two half-eggs together before they put on the ensolite). Therefore, I believe you don't need to put silicone along that trim at all if you follow the original "design" and don't poke holes through the shell, as long as there are no leaks
caused by previous damage or repairs. I didn't put any new caulk on mine, and it looks much nicer without, considering I'm not very good with caulk.
I did discover one leak, but patched it up with fiberglass from the inside by carefully pulling off the ensolite with a scraper and then fixing the leak in the fiberglass seam.
There is one flaw with the metal brackets however: they tend to rust when water reaches them from the outside, and so would the original non-aluminium rivets. This is probably the only reason why some type of caulk would be useful from the outside. But this is just to point out that a caulk-free seam can be done if you feel like doing extra work.