Guys,
Talk to Henry at Layline. They have a great riser material (nylon I think). Happily, Henrey used to won a J30 and is quite helpful. Here's how I solved the damming problem after the rise is installed...before installing, I routed out three 1.5" tracks on what would later be the bottom side of the riser. One near each end diagonally drained water the the center and the third "spillway" was in the center to drain directly back.
Never any water damming. Maybe once a month I have to flush the dead bugs, food assorted stuff that has built up.
