Replacing seacocks

[tompug]

Hi,
I bought a boat last year and am now trying to sort some problems before the new season. I'm also new to working on boats, so coming to this forum hoping you can help reduce the chance that I screw something up
One of these seacocks is stuck open and the other is not exactly filling me with confidence either. I'd like to replace them with ball valves. Can I simply unscrew them from the through-hull fitting and screw on new ones. Or am I at a big risk of snapping off the whole assembly?
Anything else I should be aware of?
Cheers,
Tom

 

[vyv_cox]

In theory you can simply unscrew the gate valves and replace with ball valves. The problem is that the skin fittings are almost certainly brass that could well have suffered dezincification. Replacements in DZR are relatively cheap and it would be false economy not to replace them.

 

[Laysula]

Replace the whole lot, skin fittings as well. I got a good price for plastic replacements by Tru design from Leesan. Plenty of videos on Youtube on how to do it.

 

[Sandy]

Welcome to the forum.

As @vyv_cox says in theory yes, but!

Personally, if you have room I'd replace them with plastic peacocks and fittings, a bit more expensive. Why stuff a bit of metal through a GRP hull when you can stuff some non corroding GRP through it?

 

[jwilson]

As the gate valves are probably brass not bronze or DZR there is a fair chance the skin fittings might also be brass. I'd change the lot either for DZR or bronze, or plastic Marelon fittings. Careful angle grinding from outside the hull is probably the easiest way to get them off.

 

[KevinV]

Anything else I should be aware of?

You ARE out of the water, aren't you?
(I once got a bit carried away fixing a raw water intake issue )

 

[tompug]

Thanks all. I think I'll be replacing them then! Looks like it will be a fun little project.

>> You ARE out of the water, aren't you?
:-D That sounds like it was a bit stressful.

 

[neil_s]

Having just done this job for the second time on my boat I would say that it's most likely that the through - hull seals will break when you apply the spanner, allowing them to rotate in the hull. Then it will be a monster pain trying to separate them and jwilson's angle grinder solution above is much the easiest. Use good quality DZR components to replace.

 

[Daydream believer]

It is OK for some to glibly tell you to change the lot but if the actual through hulls are sound then they can stay for a while & you will have enough expense just changing the valves. My ones are 19 years old & I have only had to replace the one to the black water outlet.
I suggest unscrewing the valve first. When you do this have a look up the void from outside. You may see a small " dimple about 3-4mm. Perhaps 2 of them opposite sides of the hole. If so get a flat bar & cut or grind it so it just fits inside the hole & cannot turn because it engages on the dimples. Start with the biggest one & the bar can be reduced in size as you go. Bend the bar at right handles so it forms a sot of spanner. Get someone to hold it. This will stop the seal between skin fitting & hull breaking when you undo the gate valve & fit the new ball valve. From what I have seen in chandleries the dimples are more often found on better quality DZR ones. So it is my guess if no dimples you have brass. If you have dimples it is a good chance you have DZR. It is NOT a given & you have to make your own decision on that.
When you get the ball valve off have a look at the condition of the skin fitting. Give the whole threads a clean up & look for dezincification. They show a pink tint.
If OK fit the new ball valve with tape on the thread etc & refit the hose. Again use the bar to avoid breaking the skin fitting seal.
If you have trouble getting the hose off the old fitting wrap some rag round it & keep pouring boiling water on it. This will help it expand & make it easier to pull off.
I have wood bungs of the correct size hangiing on a cord next to every sea cock plus a roll of duct tape on board for emergency. In my experience one is more likely to have failure due to a split pipe than a failed skin fitting. Skin fittings tend to fail when the operator is trying to change the hose( following blockage) or open/close a stuck valve. Thus applying side pressure on the fitting

Of course others will disagree & It is for you to weigh up the options as proffered. This only my take on it & not the definitive answer. If you have the cash & the time there is no better than replacing the lot. But cash, time & availability of parts come into the equation at some point

 

[stranded]

Having just done this job for the second time on my boat I would say that it's most likely that the through - hull seals will break when you apply the spanner, allowing them to rotate in the hull. Then it will be a monster pain trying to separate them and jwilson's angle grinder solution above is much the easiest. Use good quality DZR components to replace.

Or plastic!

 

[veshengro]

I'm sure you have already thought of it, but at least 24 hours before you even pick up a spanner, soak all the fittings/threads with something like Plus Gas or Release oil. It will make life easier when the wrestling starts.

 

[Laysula]

Back in November Sandy P was going to strip and service his gate valves. He was pretty insistent that he wasn't going to replace them or the skin fittings despite them looking pretty grim. Wonder how he got on?

 

[Birdseye]

Welcome to the forum.

As @vyv_cox says in theory yes, but!

Personally, if you have room I'd replace them with plastic peacocks and fittings, a bit more expensive. Why stuff a bit of metal through a GRP hull when you can stuff some non corroding GRP through it?

I wouldnt. The almost new enormous plastic valve on the waste system of my new boat is almost impossible to turn and with no obvious way to lube. In contrast the Blakes valves work eaily despite 20 years use. The plastic one can break as the Marelon
manual warns.

 

[langstonelayabout]

Replace anything that is brass with bronze or DZR brass.

Marelon? Never again. I had Marelon (plastic) seacocks crumbling, cracking and jamming.

 

[stranded]

Did you though. I presume you reported that - what did they say?

 

[Boathook]

I wouldnt. The almost new enormous plastic valve on the waste system of my new boat is almost impossible to turn and with no obvious way to lube. In contrast the Blakes valves work eaily despite 20 years use. The plastic one can break as the Marelon
manual warns.

I've fitted a tru design valve and skin fitting and not a problem with it what ever, apart from it being bigger than the metal fittings it replaced. One more fitting to do in the future and that will be a tru design as well.

 

[bobgarrett]

If it is too cold for sikaflex 291i for sealing a skin fitting and sealing between skin fitting and sea cock what sealant is suitable?

 

[Boathook]

I prefer arbomast br butyl for skin fittings. For the threads I use ptfe tape and a back nut so that I can lock the valve handle in the correct position. So far no problems ...

Edit. I also have this on board Fernox LS-X Leak Sealer 50ml - Screwfix Seems to work fine with saltwater and has sorted out a few minor on board plumbing leaks over the years.

 

[LiftyK]

If you are going to replace your seacocks with the metal ball valve type, in my opinion it is only a matter of time before they fail again. Despite greasing from below, my seacocks would eventually become stiff and then seize, even with regular exercising. I can’t speak for plastic seacocks as I’ve no experience of them. As Birdseye already commented, Blakes seacocks seem to last forever as it is so easy to strip them down for service. Also, as they are bolted into position, you can be sure your skin fitting will never budge.

 

[PlankWalker]

Ball valves are not the best cocks, cone cocks are, and the ones you can take apart and grease the cone are the best of all.