What must happen if it is unsafe for the ship's crew to occupy the vessel during fumigation?

In situations where it is deemed unsafe for the ship's crew to remain on board during fumigation, it is imperative that all crew members are removed from the vessel. This requirement is rooted in safety protocols designed to protect individuals from exposure to potentially hazardous fumigants. When fumigation is in progress, the fumigants used can present serious health risks, including toxic effects if inhaled or if there is skin contact.

Therefore, ensuring that no one remains on the ship minimizes the risk of exposure and harm. This approach allows for a safe working environment while fumigation is carried out. Following this protocol is crucial, as it upholds both safety standards and regulations concerning the application of fumigants on vessels.

Postponing fumigation, allowing some crew members to stay aboard, or proceeding with fumigation as planned without full evacuation would compromise safety and expose individuals to hazardous conditions. Hence, complete removal of crew members is the correct action to ensure their safety during the fumigation process.