Neds suggestion.
John:If you want to try something like Neds suggestion, you can go to an electronic store (like Radio Shack) and get these computer fans. They have them as cheap as $5 is some places and they are primarily DC (that's what computers run on). You can make a bracket with some heavy gauge wire and try it out. The amperage of the fan is usually a direct relationship to the amount of air that they move. Higher amps more air. If you can test them out at the store you will be able to see how much noise they make.When I was comming home from Hawaii last summer we had Hella fans in the berths and they were great. Fairly quiet and move a lot of air. If you are going to be at the dock and have AC power you can get a box fan a lay it over the hatch opening, these work great.