On the subject of holes in hull. I once saw a commercial boat with a single sea chest that was rectangular in shape. The top of the chest was just above the waterline. A single big opening 6" + diameter with a top notch seacock fed the whole chamber. Since the top was above normal water level you could open up the lid and get at the opening to free up any debris that clogged it. A crow bar or ram rod could be poked down to unblock anything short of a cement plug. Various take-offs fed water to all interior equipment requiring cooling water. Each take-off had suitable strainers sized to fit the hose. A 4" or 6" stand pipe with a good seacock at the bottom would suffice for most recreational boats. I used a similar setup for installing Wesmar side scan sonar that retracted into the hull when boat was under way at speed. This allowed removal of the scanner head for service, without hauling the boat. Cheers Arild