After looking at the picture, the fitting looks like a garboard drain fitting. However, I am not sure why such a fitting would be so far up on the hull. If the threaded hole is smaller than 1.5 inches, then I would doubt the paddle wheel theory. Does it thread from the inside or the outside?
Surveyors here in N.E. often recomend the installation of garboard drain plugs in order to drain water out of the bilge when the boat is haul for winter storage. These drains are installed just above the bottom of the bilge or lowest point of the bilge.
This fitting looks too high for that, although I am not familiar with the W32. If a garboard drain was fitted, I would think it to be lower and more aft that what that it is.