What must be operated during a fire and boat drill while the vessel is underway?

The operation of all watertight doors that are in use during a fire and boat drill while the vessel is underway is crucial for maintaining the safety and integrity of the ship's structure. Watertight doors are designed to prevent water from entering different compartments of the vessel, ensuring that if a fire or flooding occurs, the damage can be confined to one area. This compartmentalization is vital for both controlling the spread of a fire and for the vessel's buoyancy and stability.

During drills, the crew must practice the quick and efficient operation of these doors to ensure that they can close them promptly in an emergency situation. Familiarization with these operations is essential, as it can significantly impact the outcome of an emergency incident on board. Proper training ensures that crew members know how to handle watertight doors when they need to be closed swiftly, allowing for a coordinated response to emergencies, thereby enhancing overall safety measures on the vessel.

In the context of the other options, while fire extinguishers, emergency communication systems, and life jackets are undeniably important safety equipment, the specific operational procedure of watertight doors directly relates to minimizing risks during emergencies, making it a critical focus during drills.