I have a 17KW Onan in a soundshield with underwater exhaust that you can barely hear inside or outside the boat. During summer we keep the boat closed up to keep the mosquitoes out. I normally run it from dock to dock. It gets real hot here and we don't have an ocean breeze. I have four air-conditioners and I'm not afraid to use them. If cruising a long distance if i'll be on the flybridge i'll sometimes run my 4KW engine driven alternator with the boat opened up and forgo the use of the AC and stove. Although I have diesel heat, we don't go out as much in the winter and that doesn't justify changing my set up.