Really I think we have been talking about two different types of deck drains here. The type drain I was suggesting was a straight horizontal tube exiting the hull at the deck level, 1-inch is a very common size used on boats below 20’. I think your boat's deck is at about the water level, this was a draw back on older boats. Hammer has a later model V-20 with a higher deck. If you use floor drains like Hammer has to get any real flow you would have to exit the hull below the water line and this obviously would not work except on the trailer. I think your transom has a gap between the inner hull? and the outer hull so no matter what type drain you use it would require some sort of tube in between. If you plan to attach a tube you need to use the flanged /barbed style like the plastic pic you posted (it can be had in stainless steel)
