What is the definition and importance of the bollard pull in a vessel?
A bollard pull is a measure of the maximum pulling force (horizontal) that a ship’s engine(s) can generate in full power.
It is typically measured in tons or kN (kilo Newtons).
It is defined as “the thrust generated at zero speed ahead”.
Just like horsepower is a universally understood unit of power used to measure the performance of road vehicles, the bollard pull is a universally understood unit used to measure the pulling power of ships, mainly tugboats.
In road vehicles, the torque and speed have a close relationship. Ships like tug boats, which are designed to tow large vessels on the water, often need to generate maximum thrust/torque at low speeds.
The bollard pull is a criterion for measuring the performance of tug boat which have propellers optimized for maximum thrust at close to zero speed.
The bollard pull of a tugboat cannot be determined accurately by analytical methods; therefore, it is usually measured through a bollard pull test.
The Classification Societies have created procedures for the certification of bollard pulls.
You may follow the below link to reach a Lloyd’s Register guidance on the matter: