Not sure which "power vent" you are referring to. If it is the bilge blower, being a 500 I presume it is deisel powered, I recommend running it when you get back to the dock for 5-10 mins just to clear and oil blowby vapors out of the engine room. On a gasoline powered vessel it needs to be run for 3-5 mins prior to startup and 5-10 mins post shutdown to clear fuel vapors from the engine room.
If you are just hanging out at the dock for the weekend there is no reason to have it running.
