The Merchant Shipping (Life-Saving Appliances for Passenger Ships of Classes III to VI (A)) Regulations 1992

Boat Propulsion

3.3  Unless the propeller is so arranged so as to avoid its rotation constituting a danger to people in the water adjacent to it, the drive arrangement between the prime mover and the propeller shall be such that the propeller can be brought to rest without stopping the prime mover. Provision shall be made for ahead and astern propulsion of the boat.