Here is To Know, WHAT is Bollard Pull?

Bollard Pull is a measure of the pulling power of a vessel, comparable to the horsepower rating of conventional vehicle engines. This is crucial in maritime as it quantifies the maximum force that a vessel can apply to a stationary object, such as a dock or another ship, while maintaining a steady state. The measurement is usually expressed in tons and is determined through specific tests where the vessel is secured to a fixed point, allowing for the assessment of its capability to generate thrust as it directly influences the effectiveness and safety of the maneuvering process in various marine environments.

Bollards are short, stocky structures generally built out of metal, used on piers or docks to help moor the vessel to the port by anchoring the tow lines. In general, people are more familiar with bollards being found in major cities to prevent car-ramming incidents in public places.

Bollard pull is calculated by connecting a pier bollard with a towing mechanism on the vessel and computing the force or tension developed in the connection using a load cell or similar component.

The bollard pull closely resembles that of the drawbar pull, which refers to the coupling strength utilized between trailers and trucks. This measurement is commonly applied to tractors, trucks, and trailer haulers to assess their capacity to tow substantial loads or trailers effectively.

The bollard pull measurement is typically essential for vessels like tugs and is expressed in kilonewtons (KN) or alternative force units such as short tons (STF) or tons of force (TF). Any tugboat or vessel that must exert a pulling force beyond its own weight is mandated to obtain a Bollard Pull certification from a recognized international classification society.

IMPORTANCE OF BOLLARD PULL

Waterborne vessels utilize a standardized unit of power that is universally recognized, facilitating communication and understanding across different maritime contexts. In contrast to traditional road transportation, where the relationships between torque and speed are typically aligned, tugboats and similar vessels, which are tasked with towing substantial loads across water, must function effectively under low-speed conditions.

Thus, while their speed may appear to be extremely low, the total torque and power developed by their thrusters and propellers would be significant.

The reason bollard pull measures the force exerted at zero speed in the forward direction to confirm that a tug or support vessel can maintain a ship's stability while the towed vessel generates thrust in the opposite direction. This ensures stability and control during operations where tugs are utilized in ports to assist incoming vessels in their navigation.

However, since the larger ship moves under its own propulsion, and might not be able to quickly alter course in the event of a collision, tugs must be able to immediately stall the motion of the ship and then correct its course. This requires a near-maximum thrust to be developed in the propulsion system of the vessel. The bollard pull provides operators and manufacturers with a quantifiable value of the force exerted by the tug in such situations.

 Unscrupulous tug operators are often able to manipulate horsepower ratings on their vessels without any repercussions, since it is difficult to actually verify that the value noted down in the manuals of the vessel is accurate, especially for waterborne crafts.

Another reason for implementing bollard pull is to efficiently manage the logistics involved in the shipping industry. Heavy-duty vessels that are used to move and guide large loads, tankers and ships through a port or busy channel must be aware of the actual amount of load that they can pull.

How is Bollard Pull measured?

Measuring bollard pull involves determining the maximum static pulling force a vessel, typically a tug, can exert while stationary. The details of how bollard pull is measured by preparation for vessel setup and measuring equipment. With measurement procedure, which is towing gear, engaging propulsion, and recording the force, but by calculation and reporting data, and standardization or measurements are often standardized to account for variations in environmental conditions and equipment calibration. However, considerations always happen for measurement in environmental conditions, equipment calibration, and test procedures.  

Due to the sensitivity of the trial, minute parameters such as the salinity of the water must be kept constant. The main function of the propeller is to move a certain mass of water in a unit time, that gives the vessel the required thrust.

SUMMARY

The bollard pull of any vessel is extremely important to be able to classify its load-pulling and bearing condition by carefully controlling the testing environment and accounting for water density. Generally, it is a measure of how much external load the tug can pull. It also indicates whether a vessel can keep any larger and heavier ship or tanker in a steady condition. However, this helps in assessing the true performance capabilities of the vessel and in planning for its operational use effectively.

It is essential to conduct bollard pull tests on tugs and ancillary support vessels, as it provides the operator and manufacturer with an idea of the capability of the vessel. Bollard certifications provide a seal of quality on the propulsion of the vessel, similar to other standardizations offered on conventional items.