water
John,
Bacchus pretty well nailed what I think we have, water just shows up. I can see it running down the inside of the hull by looking under the head counter, and behind the fuel tank on the port side. I caulked the tub rail and this stopped it, but will remove the rub rail in the winter or spring to see what is going on there.
Because most of the boat has the inner liner it is hard to see what is happening.
I cut two access hatches so I could change out the goofy tank vents that were plastic and broke when in sight of the first dock, so I can see in there too, and see where water is running down.
I don't have water in the locker under the v berth, but that is probably where it is coming from in your case.
Try caulking the rub rail and see if it stops if not it could also be the stantion bases need rebedding.
Rod