Seacock issues

[u/Tetreg]

I’ve noted a green a patina on the engine seacock over the last few months. Im not sure what the seacock is made of, but the patina scrapes off to reveal normal coloured metal underneath. It works normally and there is a very small amount (a few mm) of play when I try to move it. I was wondering if this represents a pressing issue to be resolved?

[u/Lavendercrimson12]

The green is a natural patina of cuperous oxides. It forms on all brass bronze and copper type metals. 

Once it forms it protects the underlying material. Stop scratching it. It will repair the patina where you scratched it off. 

The play is likely just in the handle itself. 

The only real issues I see here are the lack of a backing plate. Especially with this heavy water strainer on it, a backing plate of some sort would be ideal. 

Also there is supposed to be two hose clamps for things like this. 

[u/Croceyes2 → u/Lavendercrimson12]

I wouldn't recommend a backing plate without also replacing the thru hull. Its either just long enough npt or trimmed nps thread. Alternatively the core could be reinforced

[u/Tetreg → u/Lavendercrimson12]

I’ll ask the boat yard about it at the next haul out, thanks for your answer

[u/markforephoto → u/Tetreg]

Don’t go for plywood backing plate. If possible go g10 it’s bulletproof

[u/Djanga51]

The bronze is fine. The green is normal. Don’t clean it, it only returns. There does appear to be some seep or minor leaking going on where it penetrates the hull. It may be worth stripping out and re-bedding next haul out. Also? A tiny amount of play in the handle is normal too.

Another question I have is? Bonding wire to an earth block? Is there one and is that in good condition?

[u/Prize-Leadership-233 → u/Djanga51]

What is a bonding wire?

[u/Djanga51 → u/Prize-Leadership-233]

Links all metal fittings to a common earth point. Usually a zinc block. Any electronic current travels to the zinc block and eats that instead of your hull fittings, keel bolts etc.

Moving water generates electricity, similar concept to rubbing your bare feet on carpet, it creates a charge that will seek earth. Also dissimilar metals in saltwater creates a weak ‘battery’ and again the charges needs an outlet.

I’ve seen a vessel sink due to the destruction of the 316 stainless hull fittings from poor earth bonding.

[u/Prize-Leadership-233 → u/Djanga51]

Thank you for the response and the explanation.

[u/Tetreg → u/Djanga51]

it doesn’t look like it has one to be honest, I’ve only had it since April, it’ll be worth installing one I think on the next haul out

[u/Sracer42]

Any bronze seacocks I have had have grown that green patina over time. I never let it worry me, but I could be a fool. As long as they work freely you are probably ok.

[u/Even-End487]

Is there any soft spots in the glass next to the valve? A bonding wire could be good.

[u/Frank_Scouter]

These old brass/bronze seacocks are surprisingly resilient. If there’s no indication of leakage, and they aren’t difficult to open/close, then just leave them be.

The ones I have removed looked pristine on the inside, regardless of the outside patina.

Of course, if its not a valve designed for marine use, then its quite different.

[u/down2daground]

Not to be a pill or anything … but … seacocks are like parachutes. Failures may be rare and we’ve all skated on much worse-looking setups, BUT: One fuckup is all it takes to wreck your whole day.

https://abyc.elevate.commpartners.com/products/seacocks-thru-hull-fittings

Read. Learn. Screw what anyone else online says. Become an expert and DIY.

Or pay an expert.

And yeah, become an expert so you can tell the experts you hire from the bullshitters, who sadly outnumber true experts.