Bollard Pull
Bollard Pull (BP) is the standard rating of the towing capability of a tug. It is the steady pulling force the tug can exert on a line secured to a fixed bollard, measured during a trial and quoted in tonnes.
Bollard pull determines which ships and tasks a tug can safely handle: port authorities and terminals specify a minimum bollard pull for berthing given ship sizes, and ocean-towage jobs are planned around the required steady and dynamic pull for the tow in expected weather.
Bollard pull is the number that decides whether a tug is big enough for the job. Too little and the tug cannot control a large ship in wind and current, or hold a tow in a seaway — so matching bollard pull to the ship and conditions is the core of safe towage planning.
How is bollard pull measured?
In a bollard-pull trial the tug pulls at full power on a line connected to a shore bollard through a calibrated load cell; the steady maximum reading is the certified bollard pull.