I know to use the blower for at least 4 to 5 minutes before starting the boat to make sure there are no gas fumes in the engine compartment, but do you keep the blower on the whole time you are running the boat or do you shut it off?
Do people still use gas detectors now, I put one on a boat years ago and it really gave a feeling of security every time I hit the key.
It worked very well, tested it with a tiny amount of fuel nearby and it was pretty cheap too.
I put a fume detector in my boat that turns the blower automatically...... If the fumes remain for more than a few seconds it sounds an alarm.... GOOD STUFF
I use the blower anytime I'm not running at planing speed (and let it run for 3-5 min. on startup). If I plan on running at idle speed a fair amount throughout the day (ie pulling a tube or the like) I will just leave the blower on all the time (easier than remembering to turn it on or off).
Engine compartment is vented so it isn't necessary to run it if you are moving. It also helps to inspect the engine compartment before launching so I raise the motor cover while I am preparing to launch and run the blower while I am backing down the ramp. Always open the engine cover when you refuel to look for leaks.
I do open the engine cover and run the blower for 4 to 5 minutes before starting the boat and then I leave the blower on so I don't have to think about it. we start and stop alot so as long as I know it won't hurt anything I will run with the blower on.