How long shall the J-bar davit hoisting line be at a minimum when attached in length with the rescue hook?

The J-bar davit hoisting line should be a minimum of 20 fathoms when attached in length with the rescue hook to ensure sufficient reach and safety during operations. This length allows for adequate maneuverability to safely deploy or retrieve a swimmer or a rescue basket from the water without putting excessive strain on the equipment or endangering those involved in the rescue. A minimum of 20 fathoms provides a balance between being long enough to operate effectively in various conditions while also considering the operational constraints typical in rescue scenarios.

Using a length shorter than this could result in compromised safety and effectiveness, particularly in rough water conditions or when the victim is at a distance. Therefore, having the correct minimum length is essential for maintaining operational effectiveness and safety standards during rescue missions.