Why you NEVER use brass below the water line!

[Maine Sail]

Hi All,Some of you may know that I have been replacing all the through hulls and sea cocks on my new to me CS36. Well on my last valve, the one under the sink, I discovered the PO had used a brass ball valve with a bronze through hull and bronze elbow. After speaking with him he told me he had installed that valve two years ago and got it in a pinch at a Home Depot and meant to replace it with silicon bronze but forgot.The picture below shows the serious toll the brass was taking at only two years old. On the sides, where the ball is, the valve is almost corroded through from galvanic corrosion. The brass acts like a zinc when used below the waterline on boats!Never, ever, buy ball valves from a home center they are brass not bronze and make sure any ball valve you buy is UL approved for MARINE USE!

 

[CharlieCobra]

Nice catch!

Better now than if ya had to close it at sea.

 

[Rick D]

And, Another Thing...

...be careful to not use brass nipples either. I did on my first boat and they almost fell off in a powder. Rick D.

 

[Ross]

There are two standard plumbing grades of

"brass" there is yellow brass which is about 35 percent zinc and there is red brass. I don't know the alloy but there is substantial differences. I have had yellow brass nipples collapse under the force of a wrench.

 

[Rob19574]

wow

My Catalina 30 was just hauled his week because of the same problem....I posted here just over a week ago about it. Same exact thing happened - sink-drain thru-hull. The PO had a yard install the valve and thru-hull. I am checking all of them while she is out.Rob