I turn it on every time before I start the boat, and I don't turn it off until it's back at the dock and the motor is shut off. Every now and then if I'm driving and we're under way I'll shut it off (back on when we stop), but that blower is pretty cheap and easy to replace so I won't be upset if it burns up and I have to replace it. Never had to replace it in my Launch after 7 years of doing the same thing. I don't really do it because I'm afraid my boat will blow up from fumes in the engine bay, but I figure it helps with overall air flow and doesn't hurt anything so why not...also now it's just habit.