Which of the following actions should you take after fueling a boat?

After fueling a boat, it is essential to put the fuel cap on tightly. This action helps prevent fuel spillage, which could pose a fire hazard and also ensures that no vapors escape. Securing the fuel cap also protects the fuel system from contaminants that could enter through an improperly closed cap.

Starting the engine immediately after fueling can create a risk of fire or explosion due to fuel vapors in the air around the engine. Opening all fuel valves without ensuring everything is secure increases the risk of leaks, and reloading passengers before ensuring the boat is ready can compromise their safety. Therefore, tightly securing the fuel cap is the most critical step in ensuring safety after fueling a boat.