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Replacing Seacocks

PostPosted: Mon Aug 09, 2010 10:15 am
by Shaun
Hi,
I thought we had discussed this before, but couldnt find it on a search of this site.

Has anyone replaced a seacock before?
How did you do it?

I need to replace my raw water inlet, on the next haul-out.... it looks like a bronze seacock, do you think i can replace it with a stainless steel one?(is SS better?) or should i keep all seacocks the same metal?

cheers
shaun

Re: Replacing Seacocks

PostPosted: Mon Aug 09, 2010 2:40 pm
by Dolphin
G'Day Shaun,
recently when I had the diesel replaced the inlet water cock was a 1/2 inch PVC that I had put on. The mechanic replaced it with what he called a "marine valve" that I think is a stainless ball in a brass housing with teflon seals. He said the PVC is not allowed by the insurance companies. Don't know why? I'd have thought that any dissimilar metals would be a no no.

I replaced the 42mm brass toilet outlet with the boat in the water. I wrapped a rag around a plug inserted in the skin fitting from the outside and mopped up any water that leaked in.
For what its worth.
Greg.

Re: Replacing Seacocks

PostPosted: Tue Aug 10, 2010 1:14 pm
by john lewis
Hi Shaun:
If you are going to replace seacocks on your boat this is how you should do it. Slip the boat, antifoul, while its up, replace all skin fittings, their is only a few,my boat has three! replace all seacocks,renew all hoses,with marine grade hose, double clamp all hoses with new stainless hose clamps, pay a bit extra and use all stainless cocks and skin fittings, get a ship wright to do it for you,at least fitting skin fittings and cocks, do it properly, i have seen many people over the years cut corners below the water line, only to find their boat sinking or sunk!! cheers John :P :P :P

Re: Replacing Seacocks

PostPosted: Tue Aug 10, 2010 1:15 pm
by john lewis
Also use stainless ball valves, cheers john

Re: Replacing Seacocks

PostPosted: Thu Aug 12, 2010 7:45 pm
by bearmcnally
Hi Shaun

Are you replacing the skinfitting ?


Regards Bear

Re: Replacing Seacocks

PostPosted: Fri Aug 13, 2010 5:13 pm
by Shaun
Hi,
I will most likely also replace the skin fitting.
Do you put sealant around the skin fitting & also the backing block etc? If yes, which one?

Getting someone else to do it is not an option here, (no shipwrights as far as i know) & not always a guarantee of getting a good result, anyway i prefer to do interesting stuff like this myself, to learn about the process.
No chandelries either, the nearest one would be a 2 hour drive(our local chandelry closed down when BCF opened up in town).
However we do have a lot of plumbing supply shops, & i wonder if they sell SS or bronze "body ball valves" , any plumbers here?

Greg, your a braver man than i, do you use sealant on the in water replacement?

cheers

Re: Replacing Seacocks

PostPosted: Fri Aug 13, 2010 6:41 pm
by bearmcnally
Hi Shaun,

Skin fittings easy but remember I'm old School. If the skin fitting has been epoxy glued in then you will have to get a fine hacksaw blade and cut the bond between old fitting and the outside of the hull.Do not cut through the fitting.Once this is done get a pair of stilsons or similar and twist off'. If it won't move hit the stilsons with a hammar this should make it let go.Clean the hole with a ratstail file and sandpaper,then clean with acetone including the new fitting.Mix some epoxy and talc together to make a putty .Butter the fitting and push into the hole(tap a timber bung into the fitting prior so you have something to hold on to)Tighten the fitting up until the fitting touches the hull,clean off ooze then nip it up.Smooth remaining epoxy around the fitting let dry and that's it in a nut shell.

PS Do not use stainless steel skinfittings underwater cause they will corrode.


Regards Bear

Re: Replacing Seacocks

PostPosted: Sun Aug 15, 2010 7:35 pm
by bornfreee
Hi guys i have just finished watching lin and Larry Pardey on dvd and he brings up this topic he uses a type that has two bolts that go through the hull, way more secure than what we use here maybe Phyl will see this post and tell us more about them as they are his dvds that i have been watching :D

Re: Replacing Seacocks

PostPosted: Sun Aug 15, 2010 10:42 pm
by Dolphin
G'Day Shaun,
I used teflon tape on the valve to skin fitting joint. I didn't replace the skin fittings, there is no way you can replace THEM in the water.
Brass valves de-zincify in water and the brass goes green and turns to mush. The spindle thread just erodes away. That was the toilet sea cock that I replaced the morning that we were leaving for the trip up the coast.
The diesel mechanic replaced the diesel in the water. He only slipped it when he needed to replace the stern tube which was leaking between the hull (fibreglass)and the brass fitting. I've got one of those silly offset long shafts.
My skin fittings have two short webs or keyways, inside the fitting, that look as though they are for a plate or bar to hold it from turning when tightening it up. I had to remove the guts of the valve to get room to turn it and when it gets to the right position I just replaced the guts. A Ball Valve probably wont have that problem. I don't like dissimilar metals in sea water.
Stainless steel will corrode badly if it can't get oxygen around it.
For what its worth.
Greg.