I'll be replacing one of my port lights and would like some advice on the best way to seal it. The instructions just say to use a sealant but doesn't specify anything in particular. I've read a number of bloggers who are quite vocal about not using any silicone sealant. 4200 gets a lot of votes. I'm a big fan of using butyl tape for deck fittings and was wondering if it's just as applicable for doing the port light. Thoughts?
Re-bedding port light with butyl tape
- Thread starter nestorph
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Check with the distributors of the product they should be able to tell you if your situation is good for the application.
The most important part is what type of ports are these and what material.....? Frame & material or are they frameless dead lights?
If they are Beckson use Dow795....
If they are frameless deadlights, there was a recent discussion in Ask An O'Day owner forum that I followed on my boat and was very pleased with how well they turned out. Dow 795 is a very different silicone than the stuff your hardware store carries.
It's a Beckson. Final question then: do I just use the Dow 795 or back it up with the butyl tape?
Beckons could be done with a combo but Dow795 for the trim ring. I would just use 795 seeing as you are dealing with silicone on the next round anyway... Do not use 4200, Lifecalk, UV4000 etc...
I concure with MS, 420, lifecalk UV 4000 etc are NOT the sealants you want to use as they don't stick well to plexiglass. Used 795 on mine and it (while messy) works great.
If you have a port that spans two openings you will want to consider that the span between the openings is white and you will be able to see a "less than full" covering of 795 in those places through the plexiglass when finished.
If you have a port that spans two openings you will want to consider that the span between the openings is white and you will be able to see a "less than full" covering of 795 in those places through the plexiglass when finished.
Messy?
I found it easy to work with vs other caulks. Tooled very easy by spritzing it with water. I laid painters tape on the plexy to get a perfect line. Gobbed on the caulk and then spritzed water and used my finger to get a nice rounded bead. After all the excess was squeezed out by my finger I pulled the tape and had a perfect line. One of the easier caulk jobs I've done and the best looking for sure.
I found it easy to work with vs other caulks. Tooled very easy by spritzing it with water. I laid painters tape on the plexy to get a perfect line. Gobbed on the caulk and then spritzed water and used my finger to get a nice rounded bead. After all the excess was squeezed out by my finger I pulled the tape and had a perfect line. One of the easier caulk jobs I've done and the best looking for sure.
Sikaflex 295i-UV. It's made for bonding plastics to fiberglass and other composites. Most Lexan windows in Houston skyscrapers are installed with this.
(BTW-- I am NOT a fan of butyl tape except for temporary installations. It lends no strength and can leak. NOT for responsible marine applications.)
(BTW-- I am NOT a fan of butyl tape except for temporary installations. It lends no strength and can leak. NOT for responsible marine applications.)
man i hope you are wrong about the butyl tape and Dow 795 i have everything on my boat re bedded with butyl including the aluminum toe rails all 56 ft of them and have installed all my Lexan with Dow 795
We replaced our fixed windows with the Sikaflex. Actually, the yard did. They fell out a year later and upon inspection by the yard owner, it was determined that proper prep was not done. You also have to use a primer and evidently, it's a very specific process. They reinstalled last fall and so far, so good. This is one reason why I had it done cuz I would not want to do it again.... The other is that caulks are worse than a virus with me. I dread when I have to do it. The owner and I had a serious discussion about using 795 and he assured me that the Sikaflex would work. It's evidently used on the Jeannaus..
