Bob, I agree the splice must have been done to solve a problem. When I removed the hatch panel from under the forward starboard settee, I could see past the bulkhead separating the water tank from the forward stowage space. I do see that it is a poly tank and not a molded fiberglass tank, which was the case on my previous Tartan 30, so I am sure that when I remove the screws from the aft part of the settee, I will get to the water tank. In my Tartan, that plywood section of the settee was actually the top of the water tank and was very difficult to remove, hopefully the Ericson will be easier.
Even without exposing the entire tank, I can see from the stowage area that there are two hoses coming off the end, one at the top and the other at the bottom. The top must be a vent line, the bottom hose is a solid grey plastic hose which I am sure goes to the sink in the head as well as to the galley sink.
The hose that I see in the splice is definitely not that supply hose, so it must be the vent hose. So now the mystery is why would the PO splice in a vent hose, it normally does not carry any water so who cares if there is leak in the hose? Even more of a mystery, is that the vent hose coming off the water tank is a clear hose reinforced with fibers, like normal water hose. The hose that I see at the splice in the head area has that same clear, fiber reinforced hose going aft probably to the transom where other vent hoses terminate. But the hose going forward is a solid black hose, looks very old and suspect, hence maybe it was bad and replaced with the splice. So is there yet another splice forward of the one in the head?? Very strange.
Right now the leak appears to have stopped, again very strange if it is a leak associated with either a bad water tank or a bad hot water tank. Now I have just started to replace the head (toilet) discharge hose which developed a leak just after the hose clamps which attach that hose to the head outlet. Phew, the smell was pretty bad, the hose leaked all over the cabin sole in the head. So if that hose also leaked some urine into the area behind the wall of the head sink and that liquid found its way forward and drained out just forward of the head area, I sure am glad I did not taste to see if was fresh or salt. I might have tasted salt for obvious (and disgusting) reasons!! You gotta be very careful what you taste.
I am now trying to pull the old head discharge hose out through the sail locker and attach a new, white sanitation hose, hope that goes well. If the leak forward disappears, well and good, if not, back to my mystery.