The "rusty rings" in your bilge are connected to the boat's "external ballast" in the keel. The "pigs" are/were loose blocks of lead just sitting in the bilge. About 200 lbs worth to compensate for the missing Atomic-4. If you have an inboard engine, no pigs. Oink, oink.

Removing the pigs makes the boat more "lively," which might not be comfortable for some. But, if you race . . .