Does anyone know what this is?

[eric boglio]

Hi All,
There's a series of these domes in the bilges above the keel on my Steel Roberts 53. I'm guessing they are some sort of containers which were used to fill the keel with oil but everyone I've asked has no idea. The one pictured is at the low point under the engine and has had oil leaking out at the base through a small hole. I'm guessing once the head volume has run out I can clean all the oil out and patch the hole, Don't know if I should then refill those header tanks with oil or leave empty, but maybe I'm wrong about what they are and someone has come across something similar and can shed some light on their function and how to deal with that hole?

[hellosailor]

Eric-
No idea what the cylinder is, but a common damage control for small holes is to get a self-tapping screw of similar diameter, slip an o-ring under the head, and screw it into the hole. Voila, plugged and sealed, and will last even when against pressure, for years. The hardest part is finding stainless self-tapping screws anywhere.

[eric boglio]

Thanks, that could work well. The cylinders are quite thin walled and the hole is pretty much where it's welded to the bottom. Not easy access and that would probably be the easiest without having to do too many contortions.

[FamilyVan]

Maybe it's where the previous owner kept his stash?

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app

[Tony B]

I never heard of anyone filling the keel with oil. If someone were to fill the keel, I would think it would be with something heavy.
The top of the tank looks like my old Halon tank.
Are the tanks removable?

[ZULU40]

The spool on the top is for a hose, its an old fire extinguisher.

[Imprezza72]

I have to agree. It looks to be an old fire extinguisher the top should have a place for the hose that is probably welded shut. Possibly it was being used for waste oil?

[farmall.dude]

Originally Posted by ZULU40

The spool on the top is for a hose, its an old fire extinguisher.

Retired Assistant Fire Chief here... Yes, it's a Fire Extinguisher. It's either pressurized by an air fitting (like a valve stem on a tire) or there's a compressed gas cylinder inside. This looks like a Kidde model that has or had a CO2 cartridge for pressurizing it.
From your description, I'd have to agree someone is using them for waste oil, but I am not sailing yet, so other than identifying the item, I defer to the experts for further analysis!

[Cadence]

Originally Posted by ZULU40

The spool on the top is for a hose, its an old fire extinguisher.

Damn, I think you are right, haven't seen one in many years. Good eye now the question what for? Doubt it is part of Robert's design. The stash theory seems to work.

[Wulf]

Eric, you mentioned a series of these? How many are there? All the same? Have you actually tried to unscrew the top?

[AfterHoursNLCT]

Are they placed over the keel bolts (if there are any)?

[Cheechako]

That looks like an old fire extinguisher. They were all over salvage places cheap years ago when they were phased out. Usually polished Stainless with bronze screw on tops. Useful for a lot of things, not sure why there though.
I made a great pressurized kerosene tank out of one.

[Cadence]

Originally Posted by Cheechako

That looks like an old fire extinguisher. They were all over salvage places cheap years ago when they were phased out. Usually polished Stainless with bronze screw on tops. Useful for a lot of things, not sure why there though.
I made a great pressurized kerosene tank out of one.

If I recall right they are soda ash, baking soda, extinguishers and made a mess. I can't recall ever seeing one made out of a steel weldable to a steel hull? Could be, that was a long time ago.

[crazyoldboatguy]

I, too, would wonder why anyone would fill a keel with oil. Oil is lighter than water - that's why oil slicks are found on top of the water.

They do look like a fire-extinguisher top. Weird.

[rdowall]

Often, inaccessable voids on steel boats are welded shut and filled with oil to prevent rusting. The fire extingusher caps are a clever idea to seal the void between the ballast and the steel plating in the keel area.

For example, Irving and Electra Johnson installed oval/half round steel rub rails on their Yankee III before they embarked on a trip through the European canals. To prevent rust under/inside the rub rails, they installed caps at each end and filled the voids with engine oil.

If my hunch is true, I'd leave them as is.