Final answer:
The exhaust blower should be operated before starting a boat's inboard gasoline engine to clear out flammable vapors that could ignite and cause an explosion when the engine is started.
Step-by-step explanation:
It is essential to operate the exhaust blower before starting a boat's inboard gasoline engine to ventilate any potentially explosive fumes present in the engine compartment. Gasoline engines can produce flammable vapors that, if not cleared out, could ignite due to sparks or heat during the engine startup, leading to an explosion. The role of the exhaust blower is to ensure there is a continual flow of fresh air, which dilutes and removes flammable vapors to maintain a safe environment within the boat. Additionally, starting an engine without properly using an exhaust blower can be against marine safety regulations and could be hazardous to both life and property.