Skin fitting advice - Tru Design

MagicalArmchair

MagicalArmchair

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My raw water inlet sea cock is looking a bit naff, so when we take Triola out this spring for her yearly spruce up, I'm looking at replacing it with one of these:

http://www.leesan.com/index.asp?m=3...t=Tru Design Seacock Kit 2" (50mm) 120 degree

Whilst the seacock is looking a bit grim, the through hull is made of good quality bronze and I am loathed to change it unless I must. Is it bad form to put a plastic sea cock onto a bronze through hull fitting? I note in the kit they do supply a through hull fitting...
 
I replaced all our underwater (except engine) with TruDesign through hulls, seacocks and tails. Don't see the point in leaving an old skin fitting but, if it's fairly new then don't see a problem.
 
MagicalArmchair said:
Whilst the seacock is looking a bit grim, the through hull is made of good quality bronze and I am loathed to change it unless I must. Is it bad form to put a plastic sea cock onto a bronze through hull fitting? I note in the kit they do supply a through hull fitting...
Click to expand...

I couldn't say, but do know that Vetus very strongly advise against mixing plastic and metal fittings in their raw water strainer plumbing, perhaps for reasons of differential expansion. If you wish to retain the original skin fittings, perhaps a DZR ball valve would be better?
Incidentally, your link is to a 50mm seacock. Surely it's not that big?
 
Thanks all, I'll just replace the through hull fitting too - metal thread on plastic doesn't seem like a desperately great idea, and that through hull is about six years old too. And recommendation on sealant?

http://www.force4.co.uk/sikaflex-291-white-300ml-cartridge.html#.VO3CRp2sU1I

Edit: And Mac, quite right! That is just one I picked at random, need to go for a crawl in my bilge to find which I need - the joys of boat ownership...
 
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MagicalArmchair said:
Thanks all, I'll just replace the through hull fitting too - metal thread on plastic doesn't seem like a desperately great idea, and that through hull is about six years old too. And recommendation on sealant?

http://www.force4.co.uk/sikaflex-291-white-300ml-cartridge.html#.VO3CRp2sU1I

Edit: And Mac, quite right! That is just one I picked at random, need to go for a crawl in my bilge to find which I need - the joys of boat ownership...
Click to expand...

I used 291i but they can also be epoxied in. See Leesan website for fixing instructions. http://www.leesan.com/uploaded_files/datasheets/tru design seacock kits install sheets.pdf
 
Sikaflex 291 is fine for bedding the skin fitting, but the technique is to tighten it gently, let the sealant set completely (24 hours) then tighten the nut fully. As for sealing the threads on Tru Design fittings the makers recommend PTFE tape, but the threads are a fairly slack fit so you need to use a lot. When I did my boat with new Tru Design skin fittings and sea cocks throughout I was given a tube of Loctite 5331 to use instead. It allows a small amount of re-orientation of fittings after setting, but still maintains a good seal.

P.S. Look up Tru Design recommended retail prices, then look at Lee San prices. I did not buy from them as their prices were higher than recommended retail quoted by the importers, who are Bainbridge.
 
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Must say I find the idea of discarding a bronze seacock that is only six years old rather wasteful.
Contrary to the advice above, I've read that mixing trudesign parts with metal (bronze/DZR) parts should be perfectly OK. Actually it was proposed that your combination, metal through-hull and plastic valve, tail etc, is likely the ultimate choice.
This was based on the zero corrosion risk on the plastic parts and the greater strength of the metal through hull in case of an impact (hitting some half sunken object).
 
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