Bluewater, as you know, my Clipper 34 did not come with the extended cover to the side decks and cockpit, so I had it added it via alloy tubing and Sunbrella canvas. However, the original aft corners of the cabin top did have drain holes, which just dumped water down onto the lower side deck near where the aft wall of the cabin joined the side deck. At least there it did not deluge into the cockpit itself, but still annoyed me, so I connected white electrical conduit (mainly because cheap and flexible, and looked ok, and not transparent like plastic tubing, which would then eventually show algae growth), to the drains and then ran it down the aft cabin corner, (fixed by cable ties screwed to the wall), and then out across the side deck and out the nearest scupper. Worked well.
Would it be possible to construct a bit of a water collection area, maybe using lengths of square section plastic, glued down and at the joins, at the aft end of the hard-top to sort of guide the water to that point and hold it there..? Then, drill out a hole through the GRP hard top where water collects the deepest, glue a tube of appropriate diameter into that hole so it's flush up top, but protrudes enough below to then fix something like the conduit drain I described, and do the same with that to run the water out the nearest scupper..? That's what I would do. It should be possible to run that conduit/tubing down the stern corner supports to the hard-top via cable ties to keep them out of the way and they would be quite unobtrusive done like that I would think.
