Manoeuvring Trawl Blocks for Vessel Steering
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Solution Overview
Problem
Large trawlers face increased fuel consumption due to high rudder drag during trawling, especially when maneuvering requires significant rudder angle changes, which are inefficient and affect trawl symmetry.
Innovation Solution
The system shifts trawl blocks laterally and longitudinally to alter the tension force moment on the vessel, allowing the autopilot to control these movements and adjust line tension to maneuver the boat without rudder deflection, thereby reducing drag and fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rudder area is increased to handle larger trawler sizes, then the manoeuvring capability is improved, but the drag and fuel consumption increase substantially
Solution Approach 1:
The patent introduces trawl blocks as intermediary elements that can be laterally positioned to adjust the warp line tension distribution. These blocks act as mediators between the trawl doors and the vessel, enabling course control without relying solely on large rudder deflections. By laterally displacing the blocks, the system creates asymmetric tension forces that generate turning moments, providing manoeuvring capability while keeping the rudder at minimal angles to reduce drag and fuel consumption
Solution Approach 2:
The system dynamically changes the lateral position parameter of the trawl blocks to control vessel heading. By adjusting the block position laterally along the vessel width, the system modifies the tension distribution in the warp lines, creating differential forces that steer the vessel. This parameter change approach enables precise course control without increasing rudder angle, thereby maintaining low drag and fuel consumption
2Speed
If large rudder angles are used during trawling manoeuvres, then the course change capability is improved, but the drag and fuel consumption increase
Solution Approach 1:
The system performs preliminary action by laterally positioning the trawl blocks before significant rudder deflection is needed. By pre-adjusting the block positions to create asymmetric tension forces, the vessel begins to turn in the desired direction through the warp line forces, reducing or eliminating the need for large subsequent rudder angles. This preliminary positioning of blocks prepares the force distribution to achieve course changes with minimal rudder intervention
Solution Approach 2:
The trawl blocks serve multiple functions: they traditionally guide the warp lines through the trawl doors, and additionally they function as manoeuvring elements for course control. This multi-functionality allows the same components to achieve both trawling operations and vessel steering, eliminating the need for separate manoeuvring systems and reducing overall drag by using the warp line tension for dual purposes
3Device complexity
If manual block adjustment is used for course changes, then the system complexity is reduced, but the heading control precision deteriorates
Solution Approach 1:
The system implements feedback by continuously monitoring the vessel's actual heading through sensors and comparing it with the desired heading. Based on this feedback, the control system automatically adjusts the lateral positions of the trawl blocks to correct any heading deviations. This closed-loop feedback mechanism ensures precise heading control, maintaining accuracy comparable to or better than manual methods while reducing the need for frequent manual adjustments and operator intervention
Data Source
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AI summary
Arrangement and method for manoeuvring a vessel (1) that is towing a load (10). The vessel has a block (4, 5) at the aft end, over which at least one tow line (6, 7) extends. The block (4, 5) is moveable transverse to the longitudinal axis or longitudinally of the vessel. The position of the moveable block (4, 5) defines a point of attack for a tension force from the tow line (6, 7). An autopilot (11) is coupled to an actuator (21) moving said block (4, 5), in order to change the moment of force about a rotation point of the vessel (1). The autopilot (11) has a calculation unit (12), which detects the tension force (W1, W2) and calculates the moment of force on the vessel (1). The autopilot can thus usea change in said moment of force to manoeuvre the vessel (1).