Yep I scored a small 40mm on a side, <0.07A fan from local Microcenter. She's a weeee tiny little thing, 5 cfm at 3200 rpm. Judging by the prototypes low, Ahem, signature I figure a few head box volume exchanges every 5 or ten minutes ought to t=do nicely. In my first vent attmpt I'll run an air flow through tubing the size of the existing holding tank vent on the boat as that will be my preferred method on board if it will maintain enough airflow out of the boat. Since this little fan draws so little, I'll atempt power first by a small solar charger. If that fails, then connection to house power via the old recirculating head pump circuit. If the little fan proves insufficient, then a bigger fan (i have several computer pullouts, as either solar ventillator or computer fan connected to the old pump-out fitting with a 1 1/2 npt elbow rigged to keep things dry.