Underwater Thruster Section Removal via Cradle and Well Extraction
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Solution Overview
Problem
Current methods for maintaining and repairing retractable thruster units on swimming vessels require expensive and time-consuming dry docking, leading to prolonged out-of-service times and high costs.
Innovation Solution
A method for disassembling and assembling the underwater section of a retractable thruster unit using a supporting cradle, hydraulic lifting devices, and auxiliary lifting means, allowing for maintenance and repair without dry docking, by securing airtightness, locking the propeller, and using lifting wires and jacks to lift and remove the underwater section for replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If dry docking is used for thruster maintenance, then repair work can be performed, but vessel out-of-service time increases and costs increase
Solution Approach 1:
The thruster unit is divided into two separable parts: the upper gear assembly that remains in the vessel and the underwater section containing the propeller that can be removed independently. This segmentation allows the underwater section to be maintained separately without requiring complete dry docking of the vessel, thereby reducing out-of-service time while still enabling necessary repairs.
Solution Approach 2:
The underwater section of the thruster unit is extracted from the vessel's propulsion system and removed through the propeller tunnel. This extraction allows the removed section to be maintained on the water or in a simplified dry condition without requiring full dry docking, thus resolving the contradiction between enabling repairs and minimizing vessel downtime.
2Ease of repair
If dry docking is used for thruster maintenance, then repair work can be performed, but maintenance costs increase
Solution Approach 1:
By segmenting the thruster into removable underwater sections, the maintenance operation is simplified and can be performed with less expensive equipment and procedures compared to full dry docking, thereby reducing maintenance costs while maintaining repair capability.
Solution Approach 2:
Extracting the underwater section allows it to be maintained independently using simpler, less costly methods than full dry docking, reducing the energy and financial resources required for maintenance while still enabling necessary repairs.
3Ease of repair
If the thruster unit is completely removed for maintenance, then repair work can be performed, but the complexity of removal and reinstallation increases
Solution Approach 1:
The segmentation of the thruster into modular sections (upper gear and underwater section) creates standardized interfaces that simplify the removal and reinstallation procedures. The underwater section can be removed as a complete module through the propeller tunnel, reducing the complexity compared to complete unit removal while still enabling full maintenance of the propeller and lower gear.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces vessel out-of-service time and maintenance costs by enabling on-water thruster unit maintenance and replacement, minimizing the need for dry docking and associated expenses.
Implementation Method 1
a first hydraulic lifting device (20) for raising and lowering said underwater section (12)
Implementation Method 2
buoyancy control means (28) for adjusting the buoyancy of said supporting cradle (21)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a method for disassembling and/or assembling an underwater section of a retractable thruster unit of a swimming vessel. In the method a supporting cradle (21) is detachably fixed to the underwater section (12) from below, and the thruster unit (10) is lifted so that the underwater section (12) is at least partly brought inside the well (17) formed in the bottom of the vessel. Lifting wires (24) of auxiliary lifting means (23) are connected to the supporting cradle (21) for supporting the thruster unit. Water is drained from the well (17), and the lower gear (13) is disengaged and the intermediate section and the lower gear are sealed. After that water is let to ingress into the well (17) and the underwater section (12) is lowered down by the auxiliary lifting means (23) to dock bottom or sea bed, from where the underwater section is picked up with a crane.