If the boat is diesel you don’t have to have a blower to extract fuel fumes like a gas powered boat. Our diesel boat has a blower that takes air from the top of the engine room to extract heat after shutdown. We have never used it. You have a choice of many bilge blowers, almost any will work just depends on what will fit and what your budget is. You can go from cheaper blowers that will burn out with continuous useage or something high quality like the Delta blowers. There are inline blowers or flange type. Your choice since they don’t even have to be ignition protected in a diesel boat.