Glass in porthole

[Machpoint005]

I'd like to know how the glass is supposed to be fixed in a standard brass (non-opening) porthole (NB: NOT how the porthole is fixed into the steel cabin side - that much I can see!).

 

I noticed the glass was slightly loose in a 12" porthole frame, and investigated further today by removing the internal lining. There seems to be nothing holding the glass in place against the outer brasswork except

(1) a solid piece of chipboard 40mm thick, with a 295mm diameter hole in it, behind the cabin lining, and

(2) 'orrible black gunge and what looks like a perished "rubber" seal, all of which was obviously applied by the painter some 7 years ago. 

 

Is it a question of using a suitable adhesive to stick the glass to the porthole frame,  or is there a bit missing from the setup? I've not been able to find a sectional drawing to tell me what the whole system should look like. 

 

[jacko264]

If it’s sealed in place any pu type sealer will bond and seal  try something like tiger sealer make sure the glass and frame is dry and grease free

graham

[Tracy D'arth]

Seal the glass into the porthole frame with black PU18 sealant adhesive and seal the frame onto the steel  with the same or better neoprene tape so that you can get it of again someday.

[roland elsdon]

We use glazing putty.

[Chewbacka]

2 hours ago, Machpoint005 said:

I'd like to know how the glass is supposed to be fixed in a standard brass (non-opening) porthole (NB: NOT how the porthole is fixed into the steel cabin side - that much I can see!).

 

I noticed the glass was slightly loose in a 12" porthole frame, and investigated further today by removing the internal lining. There seems to be nothing holding the glass in place against the outer brasswork except

(1) a solid piece of chipboard 40mm thick, with a 295mm diameter hole in it, behind the cabin lining, and

(2) 'orrible black gunge and what looks like a perished "rubber" seal, all of which was obviously applied by the painter some 7 years ago. 

 

Is it a question of using a suitable adhesive to stick the glass to the porthole frame,  or is there a bit missing from the setup? I've not been able to find a sectional drawing to tell me what the whole system should look like. 

 

It sounds like a butyl rubber tape which is a none hardening sticky stuff.  PU adhesive is much more permanent but I think much better.

Edited October 1, 2020 by Chewbacka

[Phil.]

2 hours ago, Machpoint005 said:

I'd like to know how the glass is supposed to be fixed in a standard brass (non-opening) porthole (NB: NOT how the porthole is fixed into the steel cabin side - that much I can see!).

 

I noticed the glass was slightly loose in a 12" porthole frame, and investigated further today by removing the internal lining. There seems to be nothing holding the glass in place against the outer brasswork except

(1) a solid piece of chipboard 40mm thick, with a 295mm diameter hole in it, behind the cabin lining, and

(2) 'orrible black gunge and what looks like a perished "rubber" seal, all of which was obviously applied by the painter some 7 years ago. 

 

Is it a question of using a suitable adhesive to stick the glass to the porthole frame,  or is there a bit missing from the setup? I've not been able to find a sectional drawing to tell me what the whole system should look like. 

 

It depends on what glass you have. If it is normal toughened or laminated glass then sikaflex 291i, if it is plexiglass or similar, then sikaflex 295 uv. Both are marine grade sealant adhesives. Make sure the area the glass sits in the porthole frame is clean. Apply enough sealant so that when the glass is pressed into place, the sealant beads fully around the hole on both the inside and outside. Both are low sag products so glass will be held in place during the curing time. Allow to fully cure, then with sharp knife remove excess from outside, leave inside untouched and replace liner.

 

[Machpoint005]

Thanks for all replies - sounds good. I'd wondered if the product used before was Sikaflex of one sort or another - the question was, which one! It's toughened glass, so now I know which is the right one.

 

All I need now is a nice piece of board 400mm square and 33mm thick, and a steady hand with a jigsaw. 

 

 

[Higgs]

 

    If the brass porthole was to be taken off, the procedure goes like this:

 

1. After cleaning the porthole, lay porthole front facedown. Run a decent bead of clear silicone around the ledge the glass is going to be seated on. 

2. Place the glass onto the silicone. Apply just enough pressure to see that the glass is seated well on the silicone all around. You don't want to squash out the silicone.

3. Pick up the assembly and turn over, onto a flat surface, so that the back edge of the porthole is now on the work surface. At this point, the glass will fall back and will now      be level with the back edge of the porthole, leaving the glass set back slightly from the seating edge. 

4. Wet finger and run it around the exposed silicone, to smooth. 

5. Leave to set, for a few hours. 

 

 

 

Edited October 2, 2020 by Higgs

[Machpoint005]

21 minutes ago, Higgs said:

If the brass porthole was to be taken off<<

 

Thanks, but although that was the original intention, it would mean buggering up one of the brass set-screws - so I decided it was best to leave well alone.

[David Mack]

On 01/10/2020 at 20:53, Machpoint005 said:

I'd like to know how the glass is supposed to be fixed in a standard brass (non-opening) porthole (NB: NOT how the porthole is fixed into the steel cabin side - that much I can see!).

 

I noticed the glass was slightly loose in a 12" porthole frame, and investigated further today by removing the internal lining. There seems to be nothing holding the glass in place against the outer brasswork except

(1) a solid piece of chipboard 40mm thick, with a 295mm diameter hole in it, behind the cabin lining, and

(2) 'orrible black gunge and what looks like a perished "rubber" seal, all of which was obviously applied by the painter some 7 years ago. 

 

Is it a question of using a suitable adhesive to stick the glass to the porthole frame,  or is there a bit missing from the setup? I've not been able to find a sectional drawing to tell me what the whole system should look like. 

 

If the hole in the steel cabin side is the same size as the hole in the porthole ring, then the glass is trapped between the two, and more or less any sealant will do. If the hole in the cabin side is the same size as the glass, then the glass needs to be glued to the porthole ring.

[Machpoint005]

Apologies for resurrecting a zombie thread, but having been to the boat today for the first time since last autumn, I found that my porthole remounting and resealing using "something like Tiger sealer" (see above) has been 100% successful - no leaks, no evidence of leaks (no puddles on the floor, nor even any mucky residue from a dried-up puddle), everything bone dry. Thank you, Canalworld Forum.

 

Not only that, but the engine started first kick despite a rather tired cranking battery I was expecting to have to recharge.

 

Happy bunny, beer to celebrate.