PocketShip.net

I'm spending this summer fixing up my Pocketship, and one of those is the portholes. During construction I made my portholes with a flange on both sides, so I could avoid drilling the plexiglass. Well, I'm going to remove the sun-damaged exterior flange and make mine exactly as in the plans. I'm confused however about the "marine bedding compound, preferably in black" the manual talks about. I have seen posts talking about butyl tape vs. silicon, and read on one retailer's site that for portholes, silicon is preferred (?). At this point, I think my default would be to paint the exterior-facing flange surfaces black (to hide the plywood behind it) and use clear silicon sealant. The black-tinted marine compound I have seen is <adhesive>, which I don't think I want.

If you have any advice on that or on what you think I should do, I'd be all ears!

I have repaired many boats and would never use silicon. It works for a while but when it fails it's a mess to clean up. I prefer butyl tape because if installed well it doesn't leak. When you do need to replace something butyl is easy to remove and clean up. Pick your color grey or black. Never ask a retailer for recomendation because he is in the busness of selling the product that he has. Real portholes, bronze , stainless steel, or aluminium. silcone nope never , never! Call CLC and ask them what they recomend.

Great point on silicon, thanks! You're right, it sure is a pain to clean up afterwards. I'll use butyl tape.

I second the butyl tape bedding method. I used it it many places on my PocketShip build, portholes, lazerette hatches, etc. About a month ago I had the hinge on one of the hatches break and needed to replace it. When I took the old one off the butyl tape was still pliable and easily removed and I had installed it about 8 years ago! The thing to remember about the butyl is that it will continue to squeeze out for a while after installation. So I found it's best to snug down the fasteners and then wait a few day (preferably on hot days). Do a final snug down wait a couple of more days, then trim the squeeze out with a plastic scraper. Not nearly as messy as something that comes out of a tube.

I used a MS polymer caulk for my portholes (and many other things.
That is so strong that I only need one flange on the inside and no bolts.
It stays flexible and when i want to replace the window I can cut it out with a sharp knife.
When still wet it easily can be removed with some acetone.