What is a Power Pull

A power pull is the maximum traction force a tug exerts, enhanced by advanced engines, thrusters, and winch systems for improved efficiency and reduced costs.
Force Transfer Efficiency
Advanced thrusters installed on modern tugs increase their power transfer efficiency up to 90% in comparison with about 70% for the traditional tugs. A modern tug saves 0.3 tons of fuel per hour. Considering the current price for fuel is at about $600 per ton, it manages to reduce the daily fuel cost by $180 and save up to $65,000 annually.
The upgrade enables the 360-degree rotating azimuth thruster to increase the general power transfer efficiency by 25%, and task completion is shortened by 15%. The port towing time is reduced from 40 to 34 minutes, saving over 200 hours in operating time per year and improving the working efficiency in ports by about 10%.
A streamlined hull design can cut down the water resistance about 20%, while a tug with 60-ton bollard pull may accomplish a job at 18 knots, the highest speed at which a conventional design tug would reach in similar conditions and operation is about 14 knots. Learn how tugger improvements can enhance workflow efficiency .
The ultra-high molecular weight polyethylene UHMWPE ropes weigh only a tenth of steel cables but boast a tensile strength of 180 tons, roughly double that of steel cables. These ropes serve for 5 to 7 years, reducing annual maintenance costs by 40% and increasing towing efficiency by 15%.
A professionally trained crew can increase tug operation precision by 20%, lowering the average task completion time from 50 minutes to 42 minutes and improving annual operating efficiency by 16%.
Bollard Pull Capability
Bollard Pull Capability: The maximum horizontal traction force which a tug is capable of exerting via a rope while not making any leeway. In general, it ranges from 20 to 80 tons for tugs operating in ports, although it could go as high as 200 tons for ocean-going tugs.
A 40-ton bollard pull of a medium-sized tug can easily tow an 80,000-ton cargo ship, meaning every ton of pull is approximately 2,000 times the weight of the cargo. In this respect, stronger bollard pull will reduce the accident rate by about 30%.
A tug with a 6,000-horsepower engine generally develops about 70 tons bollard pull, while 10,000 horsepower can yield in excess of 120 tons. The azimuth thrusters used in tractor tugs more efficiently convert engine output to traction, giving a tug an approximate 15% increase in pulling power. You can explore the compact tugger’s benefits for confined spaces .
These pulling tests are normally carried out in sheltered water conditions. In practice, heavy winds, sea currents, and wave height may reduce pulling efficiency by 10 to 20%. Under the extreme conditions of a rough sea with 5-meter waves, real pulling power could be only 80% of the value derived from bollard pull tests. Modern tugs may be fitted with dynamic positioning technology that could increase pulling efficiency by some 8% or so.
Where an 80-ton bollard pull tug can cost as much as $25 million, a 120-ton bollard pull tug may be as high as $40 million. In comparison, if a 70-ton bollard pull tug takes 6 hours to tow a cargo ship with a load of 100,000 tons, the same job would take only 3.5 hours with a 120-ton bollard pull tug.
Hull and Stability Dynamics
Hull and stability dynamics directly impact the traction, efficiency, and resilience of a tug in various operating conditions. The optimization of hull design and stability can lead to an improvement in fuel efficiency by 15% to 20% and reduce mission failure rates by about 25%.
The streamlined hulls are very common in port tugs. This design has the ability to save about 18% in water resistance. A tug performing a 50-ton bollard pull using a streamlined design can perform the same towing tasks at 16 knots and thereby save approximately 4 hours of operational time per day, while saving approximately over $70,000 annually at $500 per operating hour. Discover more about tug performance benefits in .
A hull with a width-to-depth ratio of 2.5:1 can retain 85% power output even in 5-meter-high waves, while tugs with a ratio below 2:1 may see efficiency drop to 65%. Besides, rolling motion in waves is reduced by 30%.
Traditional steel remains the main material for tug hulls. Composite materials have, however, brought down the self-weight of tugs by about 20% following their introduction. For instance, a medium-sized tug with a composite hull is about 100 tons lighter, with improved pulling efficiency by about 10%. Additionally, the maintenance cycle extends by 5 years, with annual maintenance costs reduced by 20%.
Engine Power and Torque
Towing capacity, fuel efficiency, and the ability of a tug to handle complicated operational environments depend directly on engine power and torque. Current tugs commonly use engines from 3,000 to 10,000 kW power capacity with more than 50,000 Nm torque—a pull force good enough to pull ships in excess of 200,000 tons.
For example, the engine power of a 70-ton class bollard pull tug is about 5,000 kW. Its propellers or thrusters are powerful enough to fight against water resistance and pull big cargo vessels. A tug's pulling efficiency can be increased by about 6% with a 10% increase in engine power. Learn how electric tugs improve material movement .
These use high-torque engines that, even at a low speed below 500 RPM, can give up to 90% power. The technology is expected to raise fuel efficiency by some 12%, reduce the wear of thrusters, and extend their service life well beyond 15 years.
That ocean-going tug would be churning out over 8,000 kW continuously, while developing a high torque to tow a 120,000-ton oil tanker in 6-meter-high waves with 25-knot crosswind—a throughput 1.5 times the output of the normal-rated engine.
An IEMS intelligently manages power output in real-time to match the demand for load. In a demonstration after the installation of IEMS, there was an average fuel consumption reduction by 18% for a port tug from 1.7 tons per hour to 1.4 tons, translating to about $250,000 in annual fuel cost savings. The average failure rate was reduced by 30%.
Winch and Line Strength
Winch and line strength is a factor directly related to the reliability and effectiveness of a towing process. Modern tugs are generally fitted with high-performance winch systems combined with high-strength ropes. Tug ropes normally have more than 100 tons of breaking strength, and the maximum pulling power of winches could reach more than 150 tons.
During actual operation, the hydraulic winch system of an ocean-going tug is capable of outputting 120 tons of traction while stationary, towing a cargo ship of 150,000 tons or so. Compared with traditional equipment, the vessel equipped with high-performance winches realizes task completion efficiency 20% higher, with average operation time reduced from 6 hours to 4.8 hours, hence saving more than 400 operating hours every year and thus enabling the ship owner to save approximately $200,000. Find out how electric tugs can reduce labor costs .
The modern tugs are increasingly using UHMWPE ropes, which have only one-eighth the weight of steel cables for the same strength but twice the tensile strength, with breaking strengths over 150 tons. Annual maintenance costs declined by 30% after switching to UHMWPE ropes, while task failure rates were reduced by 15%.
Some modern winches come with tension monitoring systems and automatic brakes capable of monitoring in real time the tension of ropes and preventing overload-related rope breaks. These systems cut operational risks in harsh environments by about 25%. Tug operations with intelligent winch systems see an increase in success rate from 70% to 90%.