Lexan Port replacement

[Morgan33mike]

I want to replace my non-opening ports on my Morgan 33 (classic) with new lexan windows. I also want to install these by surface mounting them without the use of any mechanical fasteners only using adhesive/caulk.

I have read the reviews in Practical Sailor and saw where the Ace Hardware/Clear Sealant had the best flexibility and adhesion. Does anyone have any opinions or experience in doing this. The boat will only be used on an inland Texas lake so offshore work is not a consideration.

Thanks,

Mike

[CaptKen]

After struggling for month with leaks around my plexiglass windows that are also externally mounted I stumbled across this bit of knowledge. 100% Silicone is the only thing that will stick to plexiglass. I would assume Lexan would be the same. With all the heating and cooling cycles the windows go through, I'm not sure the silicone itself will hold them. I think I would at least put small screws in each corner.

[a1sailor]

mike,
Try the Sikaflex web site and look for re-sealing marine windows, they have an excellent article. I have used their system on a previous boat and it worked well but you need to use the primer and cleaner as well. I heard that Dow makes a silicone that works too, it may be their 7000 series.
Some builders use a 2 part epoxy but I like a window seal to flex with the boat.
Why not use Acrylic? I hear cast Acrylic is very good.

[renoir]

Silicones are not good adhesives and ultimately they fail to seal. Silicones work well as formed gaskets wherein the sealing properties are realized within mechanically confined places. In addition, once applied it is almost impossible to remove all silicone residue so that a proper adhesive will workl You need a good adhesive/selant combination that will not attack plastic.

Most polyurethanes are not compatible with plastics, especially polycarbinates and plexiglass.

Use Sikaflex 295UV which is designed for just what is your application. As was mentioned already consult the Sikaflex web site for specific application information.

[maritimeplastics]

Here at Maritime Plastics, we have been doing this kind of repair for over 30 years, and Silpruf is our preferred sealant. It has more flexibility after curing...and we have had failures with Sikaflex products. Ace sealant and other silicone sealants are not worth it in a boating application. There are numerous steps which make a difference in the finish, and we'll be glad to pass those steps on if you do not have someone to "clue you in".