i've read your review before, alan. that rings a bell and was some of what i'm looking for. i like the vent control idea. my tanks will be under the floor though.
i searched for calabria's system, there's a decent description on pg 5 of this brochure... http://www.calabriaboats.com/2007_Calabria_Brochure.pdf
gate valves, 1 for each side. fills up when the hull is in the water/drains when on plane. i think i still like the scooper pick-up better with a ball valve.
mcmaster carr has all kinds of them. has anyone seen or have pics of the valves calabria uses? how about pics of the valves on a calabria?? are the openings on the transom?