What is the ONLY authorized synthetic line for use as a highline during personnel transfer?

The proper choice for a highline used during personnel transfer is double-braided polyester. This type of synthetic line is specifically designed to handle the dynamic loads and the requirements of personnel transfer operations at sea. The double-braided construction provides excellent strength and durability, while also maintaining necessary flexibility. Polyester lines have low stretch characteristics, which is crucial for providing controlled and safe personnel transfer, minimizing the potential for hazards caused by sudden stretching or breaking.

In contrast, other types of synthetic lines listed may lack the ideal properties for safe personnel transfer operations. Twisted nylon, for example, may not provide the same level of durability or resistance to abrasion compared to double-braided polyester. Polyethylene and polypropylene, while lightweight and buoyant, do not offer the necessary strength and can stretch excessively, which can compromise the safety of personnel during transfer. Thus, double-braided polyester stands out as the most appropriate choice for highline applications in this context.