Towline

Line connecting tug to tow, sized for the dynamic load expected during the operation. Conventional ocean tow is a steel-wire pendant with shock-absorbing chain and synthetic spring; harbour tug operations now use high-modulus polyethylene (HMPE / Dyneema) lines that are lighter, easier to handle, and have higher minimum breaking load per diameter than wire. The operator selects the towline length, sag (catenary), and material to suit water depth, expected weather, and tow stability. OCIMF Mooring Equipment Guidelines (MEG4) provide selection and inspection guidance.