I’ve heard tell from a primary source that sailed with him that there was a Marine Engineer on a Greek passenger ship that was drunk all the time and basically completely useless except for one task.

Due to an unfortunate design flaw if one of the sewerage tanks overflowed it filled up the compartment that held the isolation valves to the tanks.

His only job was to swim into the raw sewage and dive down to the valves and shut off the overflowing tank so it could be pumped out.