I have no idea. Depending upon the age of the boat and the location of the boat, perhaps there was no holding tank. That was back in the days when the poop was pumped right out into the water, the same water you might be swimming in. My '65 Roamer has a large discharge pipe coming right up next to the head (toilet) for attaching the direct discharge hose. Don't worry, it is capped, I've never removed the cap. Cap removal is reserved for when I want to flood the boat quickly while in deep water.