Probably one of a boat's greatest vulnerabilities is thru-hulls... ie. holes in the bottom of the boat. A seacock is the valve attached to the thru-hull that keeps the water we're floating in from becoming water that's flowing in.
Traditionally, below the waterline thru-hulls and seacocks are made of cast Bronze.
Like copper, bronze may develop a green patina. The patina itself is not a problem, but I like to clean it off with baking soda paste and a brush just to expose cracks or pits.
If there was a leak on a clean valve, like the one to the right, the green patina would show first near the problem spot.
I think the galley sink seacock has a leak from the drain hose, but it is so slight I can't see it leak... So I buffed it up and I'll watch the valve for the first signs of staining.
Sedna's seacocks resemble Wilcox-Crittenden Seacox and the link has full installation and maintenance instructions.
I won't be taking my boat out of the water for the winter, so I did want to grease the valves in place.
This is done by removing the little 1/8" drain plug(s) on the housing body. (The plug is to allow all water to escape the valve when winterizing your boat).
Screw a Grease Zerk into the hole and squirt grease into the hole. I loosen the retaining nuts on the end on the valve plug and work the valve handle to move the grease around. Then I adjust the retaining nuts, remove the grease zerk, and replace the bronze plug.
The square head of the 1/8" plug on this valve was corroded, so I replaced it with a new one for $5. They aren't necessarily easy to find, I had to order mine online from West Marine. I was able to find brass plugs for a $1.20 through a plumbing supply store, but feared they would corrode too quickly. Out of 6 seacocks on the boat, I only had to replace one drain plug and bought one as an extra.
This shows the difference in appearance between a Brass (left) and Bronze (right) plugs...
