Here is a picture of the pieces I used for the pipe. It is all 3" PVC drain pipe. The top piece that attaches to the deck is a toilet flange. I made a plywood piece that will get epoxied to the hull then the toilet flange will get screwed to that. You can see I cut some of the flange off because it was hitting the bowsprit bolts. Then there is about 24" of straight pipe then a 45 degree elbow, then a 12" straight.
The area that the chain gets diverted to does lead to the low bilge. That way any water that comes aboard with the chain can drain into the low bilge. Plus there are holes on port and starboard sides for air flow.
This pipe is not permanent yet as I want to see where I mount the windlass before I epoxy all the piping in.