definitely for making divers weights for their weight belt as about 15 people have stated and know cause they probably used them
Marketers got into the diving world in the early 80,s i believe. That is when all the coated lead weights in different colors started.. And only the old schools divers cast their own, or just picked up brand new gear that the newbies had lost .
Tanks used to be steel and 72 cubic feet of air , when pumped to the labeled psi, bit most of the wreck divers would overfill them and replace the Buiron disk, as crazy as it was. Wet suits were black, nothing else. We made pony's out of O2 tanks .
Marketers got in and took over and came out with all there money schemes like deep diver masterbat diver, diivemaster, with zero open water no hand held dives, you could buy an instructors card for a couple thousand, be a certified instructor and never had made any real dives. lot of people died in the 80's , mostly instructors, diving in the area i dove which was off NY and NJ no idea on what the industry is like now, but i was fortunate enough to learn from the ships were wood and men were iron days..
The good thing is they got 1000% better safety with mixed gas , i am sure at a very steep price.
I thought it was south Hampton NY at first reading, a lot of the tropical fish would be very close to shore in October as the gulf stream moved up, People would fill their salt water aquariums, Even off shore on the wrecks i would see angel fish and other tropicals, Doing an hour plus hang after a deep dive on air for deco and having a pilot fish for company was always interesting.

Definitely a diving weight mold. Had onne just like it.

hi - it is def. a diving weight mould. there is no "other half" as divers don't care if it has a slightly rougher side. i started diving 47 years ago and as a teenager made many lead weights with one of these. of course the dangers of breathing the lead fumes were not understood. I did help a guy use homemade wooden moulds which cost nothing to make but did not last long.

Absolutely , sorry to end the discussion. It is a diving weight mould. single process molten lead poured in and left to solidify and tapped out while hot cool mould off as needed. Belt goes through the slits from this side shown. Southampton being a port kind of confirms it?

I go with the diving weights theory. I have gone diving, and it looks very similar to the weights I used.

Is it the mold for casting the thing that holds the rails on railway track? Sorry, all technical terms have deserted me and I can't face Googling right now.

I believe this is a mold for lead weights. looks like the ones you would use for a scuba divers belt

it is a mold for making diving weights that fit on a belt

looks like half of a mould, not sure for what.

It's easy - it's a "SOUTHAMPTON" cast iron mold, that looking by the raised edges on the corners, it gets a flat plate pushed on the liquid contents, or it runs up under a vertical crucible, and the formed slits vent the air.

I'd say it's for casting lead, zink, tin, aluminium, "cupric" or white metal (alloy?) weights or packing or bearing / pillow blocks, or machine parts.

It's an Ingot mold

Bottom half of some type of mold?

This is clearly Spongebob's spatula.

How could you guys not notice that immediately?

definitely a mold for diving weight http://www.ebay.com/itm/Scuba-diving-weight-mold-for-casting-5-Lb-lead-weights-/110972566779?pt=LH_DefaultDomain_0&hash=item19d67afcfb

The casting mold for diving weight mentioned in previous posts seems to be correct... Do a google on "diving weight mold" and you will find images like http://www.lilmacmolds.com/Images/Products/A-Series/Belt_Weight_Mold/215000.gif or http://goldstar-leisure.esellersolutions.com/item/productImages/91_1.JPG

At first a lead pig came to mind.

This is what i found:
This is a Casting Mold for Diver belts, the inscription says the company "Swift"(something) and the location is "Southampton" UK.

Since it's made by a shipbuilding company, it could be for casting sacrificial (Galvanic) anodes.

Its part of a mold for making your own lead weights.

My thought is maybe some sort of tool (due to the handle) for tightning a certian shaped but or bolt or other fastner.

"SWIFT", "SOUTHAMPTON" say the letters.

Southampton is famous for ship building. My guess is it's something to do with that.

How big is this mould? How much does it weigh? Are there any tool marks or marks on the other side?

weight belt weights for scuba diving

It's a mold, probably for casting metal. Notice that the lettering inside is reversed. Of course, the question of what is molded with it is also quite interesting :-)

i'll start...
looks like something to pour molten metal in