Mysterious thru hull under kitchen sink

[Joe500]

We have two thru hulls under the kitchen sink. One is the just the drain from the sink. The other we cannot figure out.

The mysterious thruhull valve has two hoses coming off of it, one white hose coming off the top and another semi-transparent webbed hose coming off the side. We lifted up all the floor boards, the white one has a t-connector to a black one that goes off to the starboard side while the white one continues toward the stern disappearing under the fuel tank. The semi-transparent one disappears as it goes to port. The hoses are fairly thin so we think maybe they’re drains. We’ve eliminated all the obvious things that it could be we think (bathroom, engine, bilge etc.)

In the picture below of the cabinet under the kitchen sink, you can see on the left side the sink drain hose and its thru hull. On the right side of the photo, is the mysterious thruhull I’m describing with long red handle neither open nor closed. Does anyone have ideas for what this could be?

It’s been in the closed position so maybe we don’t need it. It’s leaking so we need to either replace it or fill the hole, which is why I’m asking. Any suggestions would be much appreciated.

[Pandor]

I have something that looks similar to this under my galley sink, as well. I can’t think of how the piping works right now, but with the ball valve in one position the through hull provided sea water to a foot pump for a tap at the sink. In the other position, the same foot pump drains the fridge.