I've searched the forums and can't find mention of a second bilge hose. I have a second bilge hose on #511. But I'm not sure where it goes. I can't find the other end.
The center grey bilge hose drains into the aft bilge sump. I ran a snake about 5' aft before it stopped. This would be just under the steps.
I used a camera to inspect the engine pan sumps and don't see anything.