Sealing an underwater through-hull?

[nigelmercier]

I've decided to remove my water maker and sell it, thus giving me a locker in which to stow the dinghy. The only problem that there is a 1" through-hull fitting and a sea-cock bang in the middle of it. When I next lift out I plan to glass over the hole (I'll be back for advice then) but for now I just want to temporarily seal the fitting so I can remove the sea-cock.

Obviously this will involve a temporary bung while I remove the sea-cock, but I wondered about filling with epoxy before adding a cap, probably from a plumbing emporium (unless anyone can suggest otherwise).

Any thoughts?

 

[vyv_cox]

The head of water is very small, just a few inches, so almost any form of capping will hold it. The first boat I owned had a plastic skin fitting below the waterline, probably had been for a log transducer. It had been sealed by banging a short length of broom handle into it, no screws or any other fixing. I didn't know it was there at first as it was hidden beneath a locker. It was a couple of years before I found it but had never leaked.

Not suggesting that this is good practice but illustrating the minimal requirements!

 

[prv]

If it's just "till you next lift out" I would be perfectly happy with a blanking cap screwed over the fitting. Preferably with appropriate rubber or fibre washer in it to seal against the end of the skin fitting (I assume the thread is parallel so sealing on the threads is not technically correct). Or failing that, just bungs lots of teflon tape around it like 90% of folk do...

Plumbers' merchant will sell you brass rather than DZR or bronze, but again given the temporary nature I would probably tolerate that. Main problem with plumbers is they tend not to have the larger sizes we use on boats - though you may be all right at 1".

I have two skin fittings blanked off this way - one well above the waterline which was blanked when we got the boat, and one right on the waterline which took the shower waste I have temporarily disconnected.

Pete

 

[Neeves]

Nigel,

You either have a very big watermaker or a very small dinghy!

Water maker intakes can be (maybe should be?) as low in the hulls as possible and the head (of water) might be a bit bigger than Vyv suggests. But I'd agree with Vyv that that the head will not be great and I might fashion a bung to fill the orifice (which if you ensure it fits another orifice of the same dimensions prior) and have a screw on cap on top. So the bung does not need to protrude internally nor externally. If the bung is correct you can then work on the basis the interior will be dry and your screw on cap can be sealed with CT1 or Sika. You can then dismantle when you next slip - and the bung and cap + sika should be good for years (after all no different to a removable log).

good luck

Jonathan

 

[nigelmercier]

This looks like it is good for the job: http://www.asap-supplies.com/marine...ttings/bronze-pipe-female-blanking-cap-415705

 

[northwind]

If you can, shoving a wooden bung in the hole from the outside, before you remove the fitting will reduce the amount of water coming in, and will provide you with a bit less stress while you screw the blanking plate on.

 

[Mrnotming]

Car filler, Isopon type sets underwater exothermic reaction style.does not seal, just blocks hole if a sheet of plastic used to smather it on underwater.Barge skipper I know used it in extremis to reduce inflow from rock damage so that bilge pump could cope until dry dock possible.
I must replace the large tin I carry on board, out of date now I expect.
So if it all goes pear shaped you can save the boat,esp if the water is warmish!