I want to improve the ventiltaion in my 240. I plan on adding a powered vent in the front hatch, and some clamshell vents at the rear of the boat. I've seen some pictures in the photo forum where folks have added small vents in the cockpit below the coaming. Does anyone have any suggestions or experince in adding these vents? Size? Location? I suspect that applications from 23.5's, 240's, and 260's would all be comparable. Of course, photos would be excellent! Thanks, Marc_B