The bollard pull certificate plays an important role in the sale and delivery of a tug as well in commercial deployment and contracts. Although tugs have been around for a long time, a uniform standard of a bollard pull trial has not been available. Classification societies, ship yards, operators and propulsion manufacturers all have developed their own procedure to conduct their trials. As a consequence there are large differences in the way the bollard pull trial is executed, bollard pull is defined and under which conditions. In 2014 MARIN evaluated a number of trial procedures and found large inaccuracies and differences. To develop a transparent and reliable guideline for bollard pull trials MARIN initiated in 2015 the joint industry project “Bollard Pull JIP”. The Joint Industry project is supported by a group of 31 international maritime businesses, and has the objective to understand all factors affecting bollard pull and to create a comprehensive and uniform industry standard for bollard pull trials. A thorough investigation was made to understand the factors affecting the bollard pull of a tug and sensitivities in the trial execution based on model tests, CFD, hydrodynamic calculations and full scale validation campaigns on several ship types. The effect of the following parameters were investigated:

• Distance tug to quay
  
• Water depth
• Circulation in enclosed harbours
• Water density
• Wind
• Waves
• Current
• Propeller and hull roughness
• Vessel sway and Yaw
• Towline characteristics
• Draft and trim
• Accuracy of the load cell
• Air temperature
• Fuel characteristics
• Data logging requirements
• Power measurement
• Definition of bollard pull and power rating.

Based on the research conducted and discussions with specialists in the group the International Standard for Bollard Pull Trials was developed. The standard has the purpose to ensure that the reported bollard pull figure represents the true performance of the vessel that can be met in service conditions at an acceptable level of accuracy, irrespective of the specific conditions met during the execution of the bollard pull trial that are known to affect the vessel’s performance. This standard facilitates a repeatable performance figure in accordance with clear definitions.