I have got the same Ribcraft problem.
When I did my rewiring I had to vacuum the water out of the duct before threading the cables through. The most annoying thing is that the duct always fills up then when I go down a big wave the water rushes into the console
I have lifted the rubber boot in the console which has reduced the problem slightly. This problem has been bugging me for a while. I can't see an easy way to drain the water out as the duct is too low.
How about getting hold of a vacuum speedo pickup. Mount it on the transom or use the engine vacuum pick up which is usually located on the top of the gearbox. Connect it up and slide the open other end into the duct which should suck the water out of the duct.....This may work reduce the weight on board and should be cheap..... what do you think?