What is a blower on a boat for?

It is a device to blow explosive gases out of the bilge so that they do not blow the boat up after fueling or in case of a small leak in the fuel system. The bilge blower should always be turned on and run for 5 minutes following fueling before starting the engine.  more

Too Funny Judge!!!!!! Anyway...the blower that you see the switch on the instrument panel, is for evacuating fuel vapors from the bilge of the boat. This IS EXTREMELY important to turn the blowers on for at least five minutes before you crank up the boat, whether you have just fueled up or not.  more

Judge Sludge has the most complete and accurate answer. You should try to keep a spare blower for inside the cabin, in case your main one won't work for some reason.  more