The aft emergency towing system fitted to tankers will typically consist of a wire towing pennant on a poop deck storage drum and a storage box containing the messenger and pick up gear. Frequently, the system is designed with the messenger line led from the storage box, through the fairlead and permanently attached to the wire pennant connection on deck to ensure that the equipment can be easily and quickly deployed in an emergency.

However, this means that the messenger, which may be of synthetic fibre or wire rope construction, will be exposed to the weather elements. A wire rope will quickly corrode with exposure to sea water and synthetic fibre ropes will perish if not protected from direct sunlight and funnel soot. These effects may significantly reduce the breaking load of the messenger line, possibly resulting in failure of the system in an emergency situation.

A protective sleeve fitted on to the exposed section of the messenger line will greatly reduce this risk. This sleeve may be of canvas or taken from a section of fire hose, for example, but it should still be capable of being removed to allow periodic inspection of the rope. Where wire rope messengers are fitted, the exposed section should be kept well lubricated and preferably covered with a water repellent tape.