A large rope or cable used for mooring or towing a vessel, typically greater than 25mm in diameter.
In practice
OCIMF's Mooring Equipment Guidelines and BIMCO publications on towing both emphasise the importance of selecting hawsers with sufficient minimum breaking load for the intended application and applying an appropriate factor of safety. All hawsers in service should be regularly inspected for cuts, abrasion, kinks, heat damage, and corrosion of wire cores. Synthetic HMPE hawsers require special attention because they fail with little warning and release energy with extreme speed in a snap-back event. Safe working load labels must be visible, and personnel must be trained to identify condemned equipment before use.
Regulatory detail & full definition
A hawser is a large-diameter fibre or wire rope — conventionally understood to be greater than 25 mm in diameter — used for mooring, towing, or kedging a vessel. Fibre hawsers may be constructed from natural materials such as manila or from synthetic fibres including nylon, polyester, polypropylene, or high-modulus polyethylene (HMPE) such as Dyneema. Wire hawsers are typically of independent wire rope core (IWRC) construction and are used where stretch is undesirable, such as in towing applications.
OCIMF's Mooring Equipment Guidelines and BIMCO publications on towing both emphasise the importance of selecting hawsers with sufficient minimum breaking load for the intended application and applying an appropriate factor of safety. All hawsers in service should be regularly inspected for cuts, abrasion, kinks, heat damage, and corrosion of wire cores. Synthetic HMPE hawsers require special attention because they fail with little warning and release energy with extreme speed in a snap-back event. Safe working load labels must be visible, and personnel must be trained to identify condemned equipment before use.
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