Raccoon is on a mission: Every day its six-man crew cruises San Francisco Bay and pulls anywhere from six to 30 tons of trash from the water.

For more than 50 years the U.S. Army Corps of Engineers has used the 100-foot catamaran to pull up everything from cups to telephone poles, human corpses and damaged boats.

In a previous life Raccoon was a seaplane wrecking derrick known as YSD-14, San Francisco TV station KTVU reports. Built in 1940 on Mare Island in Vallejo, Calif., the ship would collect downed aircraft all over the bay, the West Coast and the Pacific.

It was transferred to the Army Corps of Engineers in 1960, which almost immediately put the vessel to work clearing the bay. This video from KTVU has more:

Serious efforts to clean up the bay began after 1942, when a seaplane that attempted to land there struck floating debris, which caused the plane to capsize. The pilot did not survive, but the passenger — Adm. Chester Nimitz — did.

The incident spurred the San Francisco District of the Corps of Engineers to create a hazard collection debris program, at first using tugs crewed by civilians and enlisted Navy servicemen to collect floating hazards.

Today the fleet includes the 50-foot tug Grizzly and the 87-foot John A.B. Dillard Jr.