Which action can help prevent electrical fires onboard a vessel?

Using appropriate fuses and circuit breakers is critical in preventing electrical fires onboard a vessel because these safety devices are designed to protect electrical circuits from overcurrents that can lead to overheating and potential fires. Fuses and circuit breakers serve as automatic safety switches that will interrupt the power flow when they detect a fault or an excess load beyond their rated capacity. This automatic disconnection helps to minimize risks associated with electrical faults, safeguarding both the vessel and its crew.

In contrast, the other options would increase the risk of electrical fires. Ignoring maintenance on electrical systems can lead to undetected wear and tear or faults that can spark a fire. Overloading circuits for extra power can create excessive heat, increasing the likelihood of ignition. Extensive use of extension cords can also pose dangers, especially if they are not rated for the load or if they are frayed or damaged, leading to further fire hazards. Thus, using the correct fuses and circuit breakers ensures that electrical safety measures are in place, making it an essential practice for fire prevention onboard.