Originally Posted by caltexflanc
we always run them because never put the boat on plane for any long period of time. They also specifically stated NOT to run them when fueling.
I run my blowers whenever the engines are running and for about 4 hours after. That said, even without the blowers, my engine room temperature remains less than 10 degrees F above ambient when the engines are above 1000 rpm, and I tend to cruise at 1060 rpm. I suspect that if you don't want to run your blowers all the time, you may not need them at your normal cruise rpm.
As for not running while fueling, I can't imagine the logic. I typically keep my blowers on while refueling because by the time I get to a fuel dock, the engines have been running long enough to become two hot potatoes.