Which term describes a J bar used on ships?

The term 'J bar' refers to a specific device used on ships primarily for the purpose of hoisting rescue swimmers or boats. This equipment plays a critical role in marine rescue operations by facilitating the safe and efficient retrieval of personnel from the water or the launch of rescue boats. The J bar typically features a structure that allows for the smooth operation of hoisting and lowering actions, making it essential in emergency situations at sea.

Understanding the function of a J bar and its importance in rescue scenarios illuminates why it is categorized as a device specifically designed for hoisting rescue swimmers and boats. It is not part of a pulley system in a general sense, nor is it used for navigation or flight control, which would not align with its practical application aboard naval vessels.