You are operating a boat with a power ventilation system. you have just fueled this boat. how long should you let the ventilation system run before starting the engine?

You should allow the ventilation system to run for at least four minutes before starting the engine. This is necessary in order to allow the odour of the fuel to be blown away by the blower. After ventillation for four minutes you must re-check for the smell of the fuel. The boat should not be operated yet if the fuel odor is still very strong. 

26.4 is about the right time