Saltwater intake valve corrosion

Aurelia · Posted: Thu Apr 29, 2010 1:17 am Post subject: Saltwater intake valve corrosion

Take a look at the two pics and my album and give advice if you can. This is the intake valve for the head and washdown pump and was corroded when I got the boat and so are a few of the L brackets under the step below the door. The brackets are a relatively simple fix but how about that valve? I think some water sat in there for a while during her former ownership because it has been bone dry for us. Notice how the valve specifically is very rotten looking. I am just wondering how long before I turn it and it snaps off and if it will cause a leak as well. Time for a backup bilge perhaps.

Note: we don't have a trailer or tow vehicle for an easy look underneath but I am willing of course to have it hauled out if there is work to be done.

Is your 25 like this? Has anyone replaced this valve? What does that involve?

Greg

Captains Cat · Posted: Thu Apr 29, 2010 8:18 am Post subject:

Greg, the L brackets are a common problem. Dr. Bob (thataway) replaced several of his with Stainless ones. When you take them out, you've got to see if it's anchored into a cored section of flat stuff. If it is, you've got to "undercut" the core, refill it with epoxy and then drill to mount the new brackets.

Hard to tell about the valve. Looks, from the pictures that it may just be the handle/nut that is rusted. If the body of the valve is bronze, it may be OK. If the body is OK, just take off the handle (carefully) clean up the shaft and replace the handle and nut. Put a lot of penetrating oil on the mechanism before you try to get the nut loose, beware of wringing it off, that would be catastrophic.

If you need to replace the valve, it would certainly require hauling. If you do, make sure you have all the correct parts prior to the event to minimize time out of the water. That part of the bottom of the boat is probably cored, so with replacement, undercutting, etc. will be the right way to go.

Charlie

stevej · Posted: Thu Apr 29, 2010 9:41 am Post subject:

Greg, both the nut and handle on my valve were mild steel and looks like you have the same. The handle shaft in the valve is stainless so if you can get the nut off it should clean up and be ok. I struggled to find a replacement handle and ended up having a friend make me a new one out of SS.

stevej

AstoriaDave · Posted: Thu Apr 29, 2010 9:49 am Post subject:

Greg,

It is hard to tell from the photos, but that valve appears to be of the same type I initally installed in my inboard as a raw water seacock. The handle is likely the source of the rust you see. Further, it may be that the valve has pipe (tapered) threads, which do not mate well with the threads on the thru-hull (straight -- no taper).

I replaced mine with an all-bronze unit having a wide base which screwed to the hull (had to add some backing to make that work); the replacement also had a straight (no taper) thread, which increased the thread engagement over the thru-hull fitting by several turns. If yours is the same type I had originally, it may be that yours needs replacement.

Likely if you get someone familiar with correct installations to look at it, he can tell you if my suspicions are correct. Mating a pipe thread on the valve to a straight thread on the thru-hull is a common error, driven usually by the much lower cost of the incorrect valve.

Here are some photos of the change-out. Might be you can pick an identifying feature off my old valve to confirm my suspicions: http://www.pbase.com/bartenderdave/seacock

thataway · Posted: Thu Apr 29, 2010 10:31 am Post subject:

I did use a a few SS brackets on the Tom Cat, but on the C Dory 25, we drill out the holes, removed any water--and then filled with epoxy. The bracket was replaced with fiberglass (in this case triaxial cloth--something I happened to have , but biaxial is fine) and epoxy. No more screw holes, no more potential water intrusion and no more rusted brackets.

Agree on the handle. The valve itself may be teflon, plastic or SS depending on the brand)--you can just replace the handle. But it may be a good time to haul the boat, and replace the thru hull also (the valve screws n the thru hull). The core probably is not sealed at this point, and should be.

lloyds · Posted: Thu Apr 29, 2010 10:56 am Post subject:

There are probably millions of those thru hull valves out there. Many of the boats I have owned previously had two or three of them. The handle gets rusty but the rest of it is probably fine. They almost all look like that if they have been sitting in a bilge or something similar for awhile. It wouldn't bother me to take the handle off and clean it up and put it back on. The valve itself should be sound.

journey on · Posted: Thu Apr 29, 2010 12:54 pm Post subject:

The above advice is all good. This post is to mention a problem that was present in some 2005 C-25's and may explain the rust.

As you may be aware ( I wasn't) when a C-25 is in rough water, water enters through the drain tube, and then goes right back out. The anchor locker bottom wasn't sealed and allowed water to drain under the V-berth. After it filled that cavity, it then drained out through any holes in the aft part of the liner. One of those holes is the outlet for the fresh water supply. The water then would go along the inside stringer and end up in the rear of the cabin.

We found this out one summer when we were up in the Strait of Georgia. We even had a couple of inches on the cabin floor and thought we were sinking. Judy found the leak and I plugged it. We called the factory and they didn't offer any clue said they had never heard of that before. Ron/Meander told us that was not uncommon and to go to the factory. We did. They may not have ever heard of it before, but they sure knew where to look for sitting water and how to fix it.

If this happened to your boat, there would be rust in the places you found it. By the way, I use 5200 to seal the holes before I re-install the screws. Home Depot has it cheap, and it's certainly easier that routing, sealing and re-drilling. Never failed yet.

Boris

Aurelia · Posted: Thu Apr 29, 2010 1:12 pm Post subject:

Thanks for all the advice. I will see about carefully removing and the replacing the handle and nut first as well as checking the anchor locker for any potential leaks. I guess if I pull a few screws out of the floor in that area, I may be able to find wet material in the holes if water is intruding that space. I have been systematically removing and re-installing and sealing all of our L brackets on the boat. Most of them have been fine but this area is the worst. I do notice variations in the brackets as one will be corroded and the one next to it and lower on the floor looks good.

Greg

AstoriaDave · Posted: Thu Apr 29, 2010 3:30 pm Post subject:

Greg,

I was not very clear on the problem of mating a pipe thread valve body with a straight thread thruhull fitting. These photos may illuminate the issue better than any more words from me: http://www.pbase.com/mainecruising/replacing_thruhulls

Your thru-hull looks good; I don't think it needs replacing unless you find that area is cored, and the core is wet. Replacing the valve, if you decide to do it, is not a major job. Hauling out is the big bummer.

hardee · Posted: Fri Apr 30, 2010 3:01 am Post subject:

Astoria Dave,

Nice photo documentation of the valve replacement. Thanks for sharing.

Bartenders -- neat boats.

Harvey
SleepyC Moon

Aurelia · Posted: Thu Jul 29, 2010 11:21 am Post subject:

You were right, it was really just a bunch of scaly corrosion on the nut that I was able to remove and clean/lube and now it looks like new again and I am not worried about it coming off in my hand one day. I took the opportunity to replace and seal some corroded L brackets in the little bilge area as well.