Gasket for bronze thru-hulls below waterline

[Boh999]

Hi!

Exchanged all thru-hulls for new bronze ones. Really expensive! Now have to choose what gasket material to use when fitting? Most people would use sikaflex I suppose, but I am fan of this page:
http://www.pbase.com/mainecruising/replacing_thruhulls

Have been using butyl-tape successfully above the waterline. Should I use it below as well? I think these new thru-hulls will last +20 years so maybe better to use butyl-tape?

When removing stuff they fitted at the yard in 1974 using butyl-tape, the butyl-tape still looks ok! That cannot be said for 20 year old sika-like products used elsewhere on the boat.

Boat is now on the hard, of course.

Regarding fitting the thru-hull pieces together:
Thru-hull -> into -> Valve piece -> into -> pipe to hose thing.

Should I use this:
"Flax/Hemp" + goo
https://www.pswtradesuppliers.co.uk...RN-PIPE-JOINTING-MATERIAL-PIPE-FITTINGS-100G#

Rather than this:
https://www.clasohlson.com/se/Gängtätningstejp/30-8129

?

Cheers

 

[pvb]

You could use almost anything; there's virtually no pressure and if the fitting is suitably installed it's not going to move. Hallberg-Rassy used ordinary silicone sealant on through-hulls on my old 352, and that was fine 25 years later.

 

[Tranona]

I have always used polysulphide for through hulls. Seals well and easy to dismantle if necessary.

 

[AndyL]

Use Loctite 55 on the threads. It allows for adjustment after assembly.

 

[zoidberg]

There are many on here who will swear by the primacy of CT1 for that job.
I'm one of them.....

 

[PetiteFleur]

Butyl Tape is fine, used underwater several years ago and it's not leaking.

 

[ghostlymoron]

CT1/Sikaflex is suitable where their adhesive properties are needed but not where a sealant only is required.
It just makes subsequent disassembly much more difficult. Seek out a product with good resistance to salt water. Personally,
I'm a fan of butyl tape: cheap, easy to apply, excellent shelf life after use, comes apart easily and cleans up well with turps.

There are many on here who will swear by the primacy of CT1 for that job.
I'm one of them.....