Which of the following is NOT permitted on motor vessels regarding fire extinguishers?

The choice indicating that B1 extinguishers are not permitted on motor vessels is not correct. In fact, B1 extinguishers are indeed permitted and serve a vital purpose in ensuring safety onboard motor vessels. These extinguishers are designed to handle specific classes of fires, particularly those involving flammable liquids, which are common hazards on vessel operations. They typically have a good balance of size and effectiveness, making them suitable for the marine environment.

In contrast, B2 extinguishers, which can handle larger fires, as well as hand-portable extinguishers and fixed system extinguishers, are also permissible on motor vessels. Hand-portable extinguishers offer flexibility and convenience for immediate use, while fixed systems are designed for specific areas such as engine rooms, providing automated fire suppression. Each type of extinguisher is permitted due to its ability to meet safety requirements and effectively manage fire risks associated with vessel operation.