If you get pooped by a good sized wave, you'll regret blocking the exit for the 1/2 ton or so of water that's now radically ruining the trim/sailability/seaworthiness of your boat (to say nothing of your pants and shoes <g>).That open transom is there for a reason, and is a big safety improvement over the traditional pair of 2 inch hoses and scuppers.If you need to screen beer cans and/or small animals from going through it, I'd suggest using screen material - preferrably the plastic stuff.(Been pooped, and was really grateful for that transom opening.)