Marty wrote in part: I DO NOT KNOW HOW YOU CAN GRAVITY FEED FULEL FROM THE KEEL TANKS. Doulos will have eight keel tanks, each triangular in shape, pointy end down. The pick up will be as low as possible. I will have one transfer pump for each two tanks. (Easy for end-to-end tank mounting configurations. Put one pump between each two tanks.) While each tank will be about three feet high, the pumps will be mounted near the bottoms of the tanks. That way, the pumps will have a nice gravity feed, until the tanks are almost empty. These transfer pumps will push the fuel up a head of about six feet to fill a bulk tank that feeds the day tank. Even the day tank, however, is still lower than the engines. Everything is pumped up hill, yet all transfer pumps will be gravity fed. Paul Kruse