I had a few people ask to be updated on my project to re-seat my
portlights, so here it is.
I haven't finished, yet. It is a very labor-intensive process,
because I haven't found a solvent to safely remove the old sealant.
The process I've used seems to work, so far. I've had a few good
rains since my first replacement, and no leaks. I offer no guarantees
on this procedure, however!
1. Unscrew the portlight. Just do one at a time. You may want to put
down masking tape around the light, to make clean up easier and to
protect the fiberglass.
2. Use a sharp (but not TOO sharp) putty knife to separate the
portlight flange from the fiberglass. I did this with the putty
knife flat against the fiberglass, and worked the edge underneath the
flange. I just pushed it straight in. A little tough going, but slow
and steady pressure seemed to work. Once I got the putty knife all
the way through the old sealant at one point, I worked my way around
the light. On the bottom, I had to use a different strategy, because
the deck was in the way. I used a narrower putty knife, and pushed
it toward the middle from fore and aft. Once it was more-or-less free
of the fiberglass, I went inside and pushed the light out. On the
first one, I also removed the interior trim, using the same procedure.
But doesn't seem to be isn't necessary unless the portlight is
binding on the trim too much.
3. Now the fun part... cleaning the old portlight! I used my thumbs
to rub the old sealant off. This hurts. *sigh* I used the square end
(handle) of a round file to get the sealant out of the crevices. If
anyone has some ideas on how to make this part easier, let me know...
I still have most of them to do. I've considered leaving the most
stubborn stuff, but haven't had the guts, yet. I don't want to have
to do this again soon.
Two responses to cleaning off the old sealant: one suggestion was to
use a roto-tool (Dremel). This one scared me. Another suggestion was
to rub, but with a rubber sheet to save my thumbs. I haven't tried
this either yet, but may try the rubber sheet idea. May try a pink
4. I used essentially the same process to clean the fiberglass, but
that was much easier.
5. To actually re-seat the light, I put a reasonably thick bead of
silicon sealant on the fiberglass. You should be able to easily see
where the flange of the old portlight was. I put the bead of sealant
just inside this line. I allowed this to set-up for about 15 mins. I
put another bead of sealant on the portlight flange, just inside of
the screw holes.
6. Then I put the light onto the fiberglass, but not too tight.
Leave about 1/8" space between the plastic flange and the fiberglass:
i.e., don't squeeze all of the sealant out. When reading up on this,
I read that you shouldn't really think of this sealant as an adhesive
on a boat. Instead, think of it as gasket material that will form to
the space you need to fill, then cure-up. The source I read
recommended using wooden shims to maintain this space. I didn't do
this, because I didn't want to have to go back and fill the holes
left when I removed the shims. I'll probably try it in the future,
however, because the light doesn't follow the contour of the boat
very well, and shims would let me tighten it down a little better,
yet maintain a relatively constant distance. If it leaks in the
future, you can just tighten it down a little more.
7. Then I put a dab of sealant on the underside of the screw heads
and put them in. (not too tight)
8. Wait for it to cure. I waited overnight.
9. Tighten down the screws (remove the shims first, if you used
them), carefully trim the excess with a razor knife and remove the
10. Attend to your sore thumbs and fingers.
I hope this helps.