Through-Hull Fittings

[Randall Schmidt]

I have a 1984 O’Day 28. When I got her about 8 years ago I replaced the 3 frozen thru-hull fittings along with associated hoses. Alas I have been negligent in exercising the valves on a regular basis. I replaced the brass fittings with mareLon ones. They are once again frozen. I’m planning to haul her out in March to do the bottom. While she is out I can try to exert more force to get them open. If they break I’ll be sure to have replacements on hand to install. I assume if I order the replacements close to my haul-out schedule I can return them if unused. What are my chance that I can force the Marelon fittings open without breaking them? Will I know they are broken or is there a chance I think they are good and only discover the failure with a leak when I splash her? Finally do I go brass or Marlon this time?

 

[dlochner]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

 

[Randall Schmidt]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

I’m sure you are right it would be bronze. Is that better than marelon? One is connected to galley sink, one is sea water input to the diesel motor and one is output from the head when at sea. Only thinking ordering in advance to minimize costs of on-the-hard storage. Do you think there is a chance I get get the fittings to open and close w/o breaking them?

 

[Randall Schmidt]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

I do have the hull cleaned of growth regularly by a diver.

 

[dlochner]

If you have been using the overboard discharge for the head, the problem may well be calcium build up. That can be removed by removing the build up. I had the same problem, it was cured by removing the vent cap on the vented loop and injecting some acid based hose cleaner (Amazon link) and waiting several weeks. It dissolved the crud and the valve worked.

I do have the hull cleaned of growth regularly by a diver.

critters can get up into the valve and seize it.

If they are stuck closed, you could remove hose and inspect them. Seee if there is something on the inside that is causing them to freeze. If the motor intake is frozen, that's a big problem because the engine won't be cooled and the exhaust system will over heat the hoses.

 

[JoeWhite]

Do not order unless you need them. I would remove the hose and pour 1 ounce olive oil into the through hull then try to move the handle back and forth until it moves through its range. Do not use excessive force.
I regularly exercise the through hulls every 3 months. The sea water intake is closed when I leave the vessel and open when engine running.
All my through hulks are Marelon and closed when i leave the vessle. The only bronze 3 way valve is used on the holding tank between pumpout and macerator setting.

 

[Ralph Johnstone]

I would have thought that Marelon would spell the end of all problems regarding thru-hull valves. The only reason I don't have them is the lack of money to travel in such elevated circles.

I've had my bronze valves in place for 26 years now and have never had a problem with them. They will all get exercised for 6 months during the sailing season but no movement during the winter.

For your Marelon valves, try applying heat from a hair dryer when you try to free them. Maybe about 110° F max. to see if they'll move. Once they do move, try some non-pertoleum grease to keep they free.