Gate Valve

[Norway_31]

I recently acquired a 1985 Scanmar 31. I found that all of the thru-hull valves were open. All were ball valves, and I closed those when not using, except I found one gate valve for the galley sink that doesn't look that great (see pictures). The only markings on it are "1 1/4" and it looks to be a 1 1/4 inch gate valve. I've read about gate valves and understand they should be replaced. The boat was just hauled-out in Dec 2020 for bottom painting and replacement of the zinc anode. It has been in the water since then. I live in a rural part of Norway, about 1.5 hours sailing / motoring to the nearest boat yard for haul-out.

Considering how the valve appears with salt / corrosion, should I try to close the gate valve or just leave it open until I can get it hauled-out and replaced?
Thanks!

 

[Tally Ho]

If it were me, I would inspect the hose very carefully (and the clamps). Squeeze the hose to check for weak spots, cracks, etc. If the hose and clamps are really solid, I would leave the valve open (assuming you want to use the sink drain). Opening and closing the gate valve may be worse than just leaving it open.

if the hose or clamps are not in good shape, or if you really don’t need the sink drain, then close it and leave it alone until you can haul out and replace it.

You might also want to keep a wooden plug handy to plug the valve if the hose were to let go ( or the thru hull if the valve breaks off).

Greg

 

[PaulK]

Each of our through-hulls has a correspondingly-sized wooden plug tied to it - just in case. That gate valve looks like it was due for replacement ten years ago. It should have been replaced the day after it was installed. Gate valves have no place on a through-hull.

 

[jssailem]

@Norway_31 Welcome and congrats on your boat.

I can understand your concern. You identified a really risk to your boat, the possibility of corrosion to destroy your through hulls from within.

I am a believer that if I feel uncomfortable I should act and protect my boat.
You can take this approach or you can seek a more scientific based approach. Silver/Silver Chloride Reference Electrode to test your system to see if you have electrical currents eating away at your metal parts.

Silver/silver chloride reference electrode

corrosion-doctors.org

I had a near scare last year. I was concerned about my thru hulls because one of them became stiff to open or shut.

I had two through hulls that bothered me. One looked ugly, the other looked and worked ok. When I started to remove the units the ugly looking one was difficult to remove, but it needed replacement anyway. The one that was operating fine, self destructed in my hands. Here are images of the one that was working. The one that I discovered was only time before it failed and potentially sink my boat.

 

[BigEasy]

Considering how the valve appears with salt / corrosion, should I try to close the gate valve or just leave it open until I can get it hauled-out and replaced?
Thanks!

The photo may not be clearly depicting the thru hull fitting, gate valve, tail piece, clamp, and hose. BUT, the entire assembly has me very concerned. The gate valve appears to be severely corroded, then there appears to be clear fiber reinforced fresh water hose attached to the tailpiece and sink drain (that type of hose is not adequate for your intended use), and only a single hose clamp. Had a boat sink on my dock a few years ago when an old hose attached to a sink drain burst with the valve remaining open. So, as inconvenient as it may be, I would go back to marina and do an overnite quick haul to replace the thru hull fitting, proper seacock or at least a ball valve, new tailpiece, approved drain hose, and two SS clamps on each end of the hose fitments. Meanwhile, as bad as the valve is corroded I would be very concerned about touching it! As others have mentioned, wooden plugs to fit the thru hull fitting are very important things to have on board.

 

[Benny17441]

Don't try to close the valve. Make sure the the hoses are good and double clamped. The piece most likely to fail is the top part where the gate shaft goes through. Had that part disintegrate on me while trying to close the valve. In retrospect keep a cloth rag handy to curtail the inflow of water. Test the integrity of the rest of the valve body. Remove the broken piece from the rest of the valve, extracting the valve shaft and the gate. Run to the hardware store and find a threaded cap to close the opening. While it may seem a disaster, with a rag blocking the opening and some duct tape to hold it in place it will give adequate time to run to the hardware store and find a cap. If the failure extends to the main body then try to remove and use the wooden plug.

 

[senang]

Hammer a wooden plug in it from the outside untill you have the possibility to do a correct repair.

 

[scarletmoffett]

Maintenance of Industrial Gate Valve requires the regular intervention of specialists, periodic testing of the entire piping system, and comprehensive maintenance. And this is just not one of the advantages of these devices. However, the possibility of repeated repairs brings gate valves to the level of convenient and practical valves capable of working for decades without replacement. The best remedy against failures and malfunctions - is correct operation and preventive maintenance of devices. The most acceptable frequency for a complete gate valve cycle is once a month. The equipment cleans the rubbing surfaces of scale, small particles, sludge, and other things.