Watch them batteries
We have two day/night units on our center cockpit O'Day 37. Both are set to exhaust and both run all the time. They keep the atmosphere clean and sweet and were an excellent investment, though, like everything marine, vastly overpriced.The batteries are not removeable. They are soldred in and you have to take the unit apart to get at them. This voids your warranty. battery failure is considered under warranty but after a year it costs you 40% of the purchase price to send the unit back and have a new battery installed. Batteries on both my units failed in less than two years. The batteries are "C" cell Ni-Cads (1,700 mAh, I think). You can get larger capacity "C" cell Ni-Cads (2,200 mAh) from Radio Shack and with a little care and ingenuity replace the existing ones and make your new ones easily replaceable. The larger capacity will also keep the units running longer in sunless weather.