Fitting a new plastic (or nylon) skin fitting

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steve yates

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I have removed the originals of these 1" White Plastic Deck Drain Socket Drainage - GS Products and got replacements from dauntless chandlery in benfleet, any tips on refitting them?
Can I use butyl tape as a seal around the flange before tighening up the nut? or should a smear some epoxy under the flange to ensure it sticks to the hull when I tighten up at the other side? or is sikaflex preferred for these?
One is the cockpit drain so below water level, the other is the sink drain and on the waterline.
Thanks.
 
steve yates said:
sticks to the hull
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One is the cockpit drain so below water level, the other is the sink drain and on the waterline.
Thanks.
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Perhaps I misunderstand, but I believe these items are intended as 'through-decks' rather than 'through-hulls'.
If you want skin fittings that are located under or near the WL, you should use them together with valves, so need to be threaded. TRU design make plastic/composite ones.
 
Butyl tape is really fabulous for deck fittings. I wouldn't use it below the waterline though. TEK7 IS GREAT, OR CT1, sikaflex etc. Below the waterline.
 
If near or below waterline, I would use epoxy with colloidal silica. Many others use sikaflex or similar.
 
Saying "I wouldn't use plastic below the waterline" is like saying "I wouldn't use metal below the waterline". There lots of plastics and lots of metals.
I wouldn't use some of either under water. How many who say "no plastic below the waterline" have metal log or depth transducers?
 
I said "I wouldn't use "plastic" thru hulls below the waterline" I'd want to know what sort of plastic. I'd be quite happy with Marelon.

"The Forespar Marelon Ball Valves and Thru-hull fittings meet and exceed the ABYC ... Marelon meets or exceeds ABYC (American Boat & Yacht Council) and ISO"
Marelon ABYC & ISO
 
I have no problem with the right plastic underwater, indeed I have such through-hulls and sea-cocks (though Trudesign rather than Forespar, which also meet those standards). Indeed I have a "plastic" boat - glass reinforced plastic - much of which is underwater.
My issue is in the dismissal of "plastic" which includes Marelon etc. which though its manufacturer studiously excludes the term, is a plastic.
But I am sure we also agree that many plastics are not suitable for marine applications.
 
Graham376 said:
Personally, I wouldn't fit the type the OP has linked to anywhere near or below waterline. Composite ones such as Marelon or Trudesign are obviously OK.
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This be the crux… there’s plastic (cheap/weak - but handy as semi-disposable for locker lid drains etc.) then there’s composite (strong!) e.g. TD/Marelon.

If you epoxy in the type of fitting above, you’re eventually just likely to end up with a bit of broken plastic requiring mechanical removal.
 
RJJ said:
If near or below waterline, I would use epoxy with colloidal silica. Many others use sikaflex or similar.
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That's seriously permanent. You might want to remove the fitting at some point. An adhesive sealant such as the Tek7 or CT1 mentioned above, or even the wrong type of Sikaflex is unnecessary where the component is non load-carrying, a simple sealant is all thet is required. I have read in other posts on these forums that Butyl is fine.
 
Yes, it's permanent all right. Trudesign recommend it along with other options.

When I want to remove it, I'll drill the whole lot out again.
Spirit (of Glenans) said:
That's seriously permanent. You might want to remove the fitting at some point. An adhesive sealant such as the Tek7 or CT1 mentioned above, or even the wrong type of Sikaflex is unnecessary where the component is non load-carrying, a simple sealant is all thet is required. I have read in other posts on these forums that Butyl is fine.
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RJJ said:
Yes, it's permanent all right. Trudesign recommend it along with other options.

When I want to remove it, I'll drill the whole lot out again.
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This is the method we’re currently using now to fit new TD skin fittings all round. I was initially sceptical - then thought: Why not make it ‘part’ of the hull? Why open a new tube of sealant (when there’s always epoxy on the go)? And why - barring some disaster - would I ever need to remove it again in our ownership?

Hopefully don’t come to regret it…!

But - as above - don’t try this on plain/cheap plastic skin fittings IMHO! (If possible, don’t use them anywhere through the hull at all)
 
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