Installing Frameless Ports

[triton318]

I have been reading and researching (here and elsewhere) and my head hurts. Sika Flex 295, Dow 795, butyl tape, mechanical fasteners or not. I'd like to run by you what I've tentatively come up with to get your thoughts and suggestions. First, decisions already made and criteria:

• Using 3/8" polycarbonate (already purchased three years ago after not doing enough research; probably would've gone with acrylic)

• I won't be reusing the old frames; ports will be installed on the outside of the cabin sides

• Strength, watertightness, and longevity (of watertightness) is primary concern; aesthetics are secondary

Given these criteria, what do you think of the following? If you think something won't work, please tell me why and explain what you would do differently. Thanks!

[mitiempo]

Jay
Looks like it will work. But why not run the bolts in from the outside instead. You could use nyloks inside, acorn nuts, or hide the fastenings with trim.

[triton318]

But why not run the bolts in from the outside instead.

Thanks for the reply. My thinking is that by drilling and tapping holes through the cabin side and screwing the bolts into the threaded holes and sealing with epoxy, I would essentially have studs and would have one less location to worry about water finding its way in. Replacement of the port would then be possible by removing the nuts on the outside. I know most of the members on this forum are going to cringe at the thought of having nuts/flat washers up against the port on the outside, but again, aesthetics are secondary and I'm fine with the proposed appearance.

[earlylight]

You may wish try barrel nuts similar to these from Jamestown Dist.

[Rachel]

I'm probably missing something obvious here, but could you run the fasteners in from the outside (nuts on the inside) and still tap the fiberglass cabin sides (and have the holes through the poly oversized, as you plan already). Or is there some reason that the fasteners have to go through the tapped section first, and then go on to the nuts on the outside?

Rachel

[mitiempo]

I think most would go from the outside with the tapped section acting as the nut, possibly the only nut as you could even do a blind tap (Not go completely through the inside wall) and seal the hole with epoxy on the threads. There is not that much force outwards on a port - the danger comes from it being pushed in. If it is thick enough for its size it should have no problem with that. Or you can use barrel bolts as pictured earlier. All the bolts do is hold the plexi or polycarbonate to the cabin side with the sealant in between. And they should not be too tight. The outside of the port should not look scalloped from bolts tightness. Just last week at a marina I saw a Cal with smoked plexi ports that were too tight and you could see it's obvious waviness as it was pulled against the cabin side with each bolt but bulging out in between them.

[Quetzalsailor]

Toooo easy.

Mount the port from the inside. Bury the nut and tapped hole with filled epoxy in the thickness of the house side (not exposed outside). Fill, shape and paint the sawn edge. Gasket and sealant on the inside. Cap screws through port into the prepared holes. Copy Hirilonde's bonded wood trim to hide the cap screws.

Mistakes I made when replacing the Morgan 27s ports included: using flathead bolts in lieu of the original flathead screws (both are wrong since the countersink shape tends to act like a wedge and split the plexi); fitting too closely within the rabbet in the Morgan's house; no clearance around the bolts; wrong sealant.

Earlylight's 'sex bolts' or 'Chicago screws' in stainless is a nice thing to know about; I'd seen them in aluminum years ago.

[sail_fix]

We replaced our four large fixed ports in '95. Lexan, frameless, and screwed down with a pan head 3/4" ss screw about every 6 inches around the perimeter. Your screw length will be calculated so that the points will not quite show on the inside. The "trick" is to have the external lens float on a bed of sealant about 1/8 to 3/16" thick. You will need several full tubes of black LifeSeal. This will adhere to plastics and not dissolve them.
You already mention over-drilling the holes in the plastic. Good.
Have the lenses routered all around the edge, quarter round.

And the aforementioned "trick"....... once you get the holes done, and all the dry fit done, and all the blue 3M tape on all around... mark each hole with a toothpick. Then gun on a thick layer of black LifeSeal. Then put little 1/8" thick O rings over each toothpick, and then put lens on. Press the lens down with hands to force out excess sealant, and then note it rests on the O rings. Remove the picks one by one and insert each ss screw. Tighten to where the lens bears on the O ring, and no further -- do not dimple the lens at each fastening.
Oh yeah, sand the lens bearing-surface around the edge with some 80 grit only where it will bond to the sealant. Also sand the cabin side frp with some 80 grit only where the lens will cover/adhere to it.

Have a plastic bag in a 5 gallon bucket at hand and a helper to hand paper towels to to throw away. You will still probably have sealant in your hair and not remember how it got there. :)

Once you have all the excess goo off, it's time to have one beer.
After a few hours, remove the protective paper from the lens on both sides where it was left on everywhere it was not intended to bond to something.
Have another beer at that point!

We went thru this process in '95, and have not had one leak since.
Our four fixed ports are all a little over two feet long and there is considerable expansion coefficient in the Lexan compared the frp cabin side.

L

ps: other boat restorers may have other methods, and whatever works is just fine.
pps: some folks worry about strength... but I would note that once the sealant cures, the screws are just there for looks........