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Best way to seal portholes to steelwork


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1 hour ago, Jen-in-Wellies said:

You are all wrong. The best way to seal a porthole is to weld a circle of steel across the hole. Absolutely no chance of any water getting in. Or light for that matter.

Jen :)

 

Like it!

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Previous portholes were held in with a sticky backed rubber tape like a narrower weed hatch tape. The windows came off easily but I'm not convinced about the sealing. 

Presumably butyl tape is sticky both sides so should absorb uneven surfaces better?

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Tried butyl rubber tape on the little portholes in the pidgun boxes. It worked but was not very neat and difficult to take the portholes out later. More recently have made gaskets out of neoprene sheet for both the pidgun boxes and cabin portholes. This is much better. Had to do the bolts up quite tight to compress the neoprene enough to seal. Not viable with m6 brass bolts so did it with steel studding and nuts, then replaced with the brass bolts one at a time.

..............Dave

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2 hours ago, Boredrider said:

Roof and Gutter sealant from a DIY shed. Cheap as chips, and cleans off with white spirit.

Second for that just been using it on my windows. Not sure why windows only leak when its raining, lol.

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On 6/11/2017 at 11:34, starman said:

What do the pundits recommend? Window tape or Sikaflex? My worry about window tape is that it will leave a visible dark circle round the porthole against light paintwork. 

Arbomast BR Butyl based Sealing Compound,Butyl Rubber Joint Sealant,recommended for Marine Bedding applications

Much less fiddly than the Tape and available in Standard 380 Mill Cartridges

CT

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4 hours ago, blackrose said:

I would just use Sikaflex, Marineflex or Stixall. The only reason being that all 14 of my portholes are sealed with Marineflex and have never leaked in over 12 years.

never had a leak in 12 years?  ...................   you must be bursting by now Mike :rolleyes: 

Edited by Murflynn
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Just now, blackrose said:

Not in my experience.

I sealed my bullseye glass to the brass rim & the rim to the roof with sikaflex about 7-8 years ago....this winter it started to leak...when I removed it the sikaflex had turned to a powdery dust on both parts. UV is my only answer. I have used it a lot in the past but I now use butyl tape where possible instead. It seems to cope much better with expansion and keeps a good seal...it's also much tidier to apply

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20 minutes ago, frangar said:

I sealed my bullseye glass to the brass rim & the rim to the roof with sikaflex about 7-8 years ago....this winter it started to leak...when I removed it the sikaflex had turned to a powdery dust on both parts. UV is my only answer. I have used it a lot in the past but I now use butyl tape where possible instead. It seems to cope much better with expansion and keeps a good seal...it's also much tidier to apply

Interesting you say that, our windows were put in with foam tape then the edges sealed with a rim of Sikaflex EBT+ and a year later it's all crumbled to dust. Again I suspect UV damage. I wonder whether one of the marine grades would have performed better. 

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1 hour ago, starman said:

Interesting you say that, our windows were put in with foam tape then the edges sealed with a rim of Sikaflex EBT+ and a year later it's all crumbled to dust. Again I suspect UV damage. I wonder whether one of the marine grades would have performed better. 

I used sikaflex 221 which is supposedly marine/automotive grade. 

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3 hours ago, frangar said:

I sealed my bullseye glass to the brass rim & the rim to the roof with sikaflex about 7-8 years ago....this winter it started to leak...when I removed it the sikaflex had turned to a powdery dust on both parts. UV is my only answer. I have used it a lot in the past but I now use butyl tape where possible instead. It seems to cope much better with expansion and keeps a good seal...it's also much tidier to apply

To be honest I was thinking about Marineflex and Stixall. I never use Sikaflex simply because it's more expensive and I'm sure the others are just as good. But I have bedded in all sorts of fittings to the outside of my boat with Marineflex and Stixall and never had a problem with UV degradation.

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