Corrosion question: what is going on and what do I need to do about it?

Northbeach · #1 (**permalink**) 07-25-2008

The boat is a 1973, 24’ fiberglass Cal T/4 that is kept in fresh water. Inside the cabinetry below the sink (that is never filled with liquid) on the bottom of the boat is a valve that has two hoses attached to it. One hose is the drain from the sink, the second hose leads to a water pump that feeds the sink. I have owned the sailboat for approximately 4 years and have never used the pump or the sink. The valve does not leak, however I don’t like the looks of this at all. What is going on with the discoloration? I believe this valve is a through hull but I am not 100% certain. Why is the underlying surface of the hull discolored next to the valve? Is there any reason not to remove the whole thing on a boat this size? Here is a link to Flickr.com that has some pictures of the corroded valve that I took tonight. Flickr: T/4's Photostream

camaraderie · #2 (**permalink**) 07-25-2008

Northbeach ....I think it is highly unlikely that you have followed those two hoses correctly. I believe they are both water supply hoses...perhaps you have a head or head sink pump that one runs to? Anyway...no matter....you have a garden hose type gate valve on there and that is a definite NO NO!! Corrosion is bad but does not appear to be an urgent issue. In looking at the fitting I am thinking that it may be a water tank fitting rather than a through hull, in which case there is no danger but you probably should replace all th hose and fittings anyway when you get a chace to. The two ways to check on whether it is a though hull are:
1. dive under the boat and look for a hole in the same position.
2. CLOSE the valve and remove the clamp and one of the hoses. Then open the valve. If you get water bubbling up it is a through hull...if not...it is your fresh water tank which holds 15 gallons according to specs.

sailaway21 · #3 (**permalink**) 07-25-2008

I'm not familiar with that boat but that flange looks more like a tank flange than a thru-hull to me. The corrosion doesn't look too out of the ordinary; you might clean it up when you change that gate valve out for a ball valve. If it's off a tank a brass/stainless valve will work alright-if it's a thru hull, you'd best use bronze.

sailaway21 · #4 (**permalink**) 07-25-2008

AFOC comment of the night. Garden hoses are generally attached to sill cocks and sill cocks, be they anti-siphon or conventional, are globe valves. Globe valves, most commonly seen in boiler drains, have a rubber seat. Gate valves, which are used as block valves in most applications, have a brass gate and no seat. The valve pictured is a gate valve and, after removal, will be of little marginal utility in any gardening scenario.

I'm sorry, Lord. I just couldn't help it. It was just a Larry the Cable Guy kind of moment. Cam, I'll just bite myself, thank you. (g)

Northbeach · #5 (**permalink**) 07-26-2008

Cam, Sailaway thanks for the feedback. I ask questions because I don’t know, I appreciate the information. I am headed back to the boat again tonight to look at it. I am almost certain that one side is hooked up to the sink drain and the other side to a pump. I agree it looks like a tank rather than the hull. Frankly I am afraid to touch the valve as it is not leaking. I think I will wait until the next sunny day and go for a swim and a look see. I have some pictures of the last haul out but they are inconclusive.

camaraderie · #6 (**permalink**) 07-26-2008

Hope you tasted good...if not I'll have CD send some bar-b-q butt sauce over!!

SEMIJim · #7 (**permalink**) 07-26-2008

Thing is, Northbeach, it wouldn't make any sense for that to be hooked-up like you say it is, with one hose going to a pump for the sink and the other going to a sink drain. That is: Unless somebody at some point unthinkingly got some lines crossed. (It still wouldn't make any sense, but it'd explain how it got that way.)

Jim

SEMIJim · #8 (**permalink**) 07-26-2008

Quote:

Originally Posted by camaraderie

Hope you tasted good...if not I'll have CD send some bar-b-q butt sauce over!!

Bar-Butt-Q sauce?

Jim

sailaway21 · #9 (**permalink**) 07-26-2008

Quote:

Originally Posted by SEMIJim

Bar-Butt-Q sauce?

Jim

The boy's in North Carolina and he's done gone native. (g)

Northbeach · #10 (**permalink**) 07-26-2008

I went back and did some more investigation. As you are looking at the “T” valve under the sink, the right side hose connects up to the bottom of the sink. It is in fact the sink drain outflow. The left side of the “T” valve connects up to a hand pump that supplies water into the sink. Since the hoses are clear, I placed a lit flashlight on top of the drain hole in the sink and it illuminated the tube below the sink that led to the “T” valve.

Once I operated the pump at the top of the sink I could see water and some debris flowing from the “T” valve up the transparent hose (left side) to the bottom of the pump that was discharging water into the sink. I could also see water draining from the sink flowing down the tube and back to the “T” valve.

Presumably this system was to be used while underway, so as to provide some water exchange; otherwise you are just recycling the sink discharge back into the pump and into the sink – weird. There is a second hand pump that discharges into the sink with a separate supply line; apparently this one comes from the water tank. I have never had an occasion to use the water tank. Nothing came out of this second pump when I tried to pump it.

Cam, Sailaway what do you recommend; do I replace the through valve with a new one and keep the system, cap it off and be done (as was done with the originally installed toilet discharge through hull), or remove the whole thing and fiberglass over the hull where the through valve is located? If the through hull isn’t there, then it can’t leak. What is the advantage of this filthy system? If I really need a drain, for the sink I never use for liquids, I can drain it temporarily into the bilge just like the ice box is currently plumbed.

This boat has two Achilles heels that keep me from using it for more extended voyages. One is this valve. I have the wood plugs, but should it fail I would have a real problem. The second thing that troubles me is the tube that connects the cockpit drain to the discharge hole in the bottom of the hull in front of the rudder. The ‘tube’ looks like it is rubber and I have no idea what condition it is in. Nothing is leaking now. If that “rubber tube” fails it will flood the entire boat, and the water around here (Seattle Washington area) is really cold.