Ship Fin Stabilization Asymmetric Geometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ship fin stabilization designs face challenges in optimizing fin surface area for stabilization at anchor or zero speed, as they require additional measures like longer shafts, leading to increased bearing forces and material costs, and cannot be fully pivoted into a fin pocket, reducing stabilization effectiveness.
Innovation Solution
The fin is arranged with its short side parallel to the ship's outer skin and long sides swept backward, with the fin shaft axis positioned at 10-30% of the mean chord length, allowing for over 90-degree pivoting and increased effective area for stabilization at anchor without altering the pivot column's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the fin shaft is positioned at the front edge of the fin with the longest possible chord length to optimize effective lever arm for stabilization at anchor, then the effective fin surface for stabilization at anchor is improved, but the aspect ratio of the fin is reduced compared to conventional fin designs
Solution Approach 1:
The fin is designed with asymmetric geometry where the chord length varies along the span, with the longest chord at the front edge and progressively shorter chords toward the rear. This asymmetric configuration maximizes the effective lever arm at the pivot point while maintaining an acceptable overall aspect ratio, resolving the contradiction between maximizing effective surface area and maintaining proper fin shape characteristics.
2Ease of operation
If additional measures such as shaft extension and simultaneous shifting of the pivot column toward amidships are implemented to enable full pivoting into a fin pocket, then full pivoting capability is improved, but bearing forces increase
Solution Approach 1:
The fin shaft is designed with a flexible or dynamically adjustable configuration that allows full pivoting motion without requiring excessive structural reinforcement. The shaft may incorporate flexible sections or dynamic support mechanisms that adapt to the pivoting motion, enabling complete retraction into the fin pocket while avoiding the need for extended shaft lengths and associated high bearing forces.
3Ease of operation
If additional measures such as shaft extension and simultaneous shifting of the pivot column toward amidships are implemented to enable full pivoting into a fin pocket, then full pivoting capability is improved, but shaft deflection increases
Solution Approach 1:
The fin shaft employs a dynamically optimized structural design that maintains rigidity during operation while allowing full pivoting motion. The shaft configuration, including its support structure and connection points, is designed to minimize deflection under operational loads while still achieving complete retraction into the fin pocket, eliminating the need for extended shaft lengths that would increase deflection.
4Ease of operation
If additional measures such as shaft extension and simultaneous shifting of the pivot column toward amidships are implemented to enable full pivoting into a fin pocket, then full pivoting capability is improved, but material costs increase due to a longer shaft
Solution Approach 1:
The fin shaft is designed with an optimized length and configuration that achieves full pivoting capability without requiring excessive material. The dynamic design allows the shaft to achieve complete retraction into the fin pocket while maintaining a compact overall length, thereby reducing material costs compared to designs that require extended shaft lengths.
5Reliability
If the fin has a high aspect ratio optimized for stabilization while underway, then stabilization performance underway is improved, but the effective area behind the shaft axis is reduced for pre-anchor stabilization
Solution Approach 1:
The fin employs asymmetric chord distribution with the longest chord at the front edge and progressively shorter chords toward the rear, creating an optimized area distribution that provides sufficient effective area behind the shaft axis for pre-anchor stabilization while maintaining the aspect ratio needed for underway performance. This asymmetric geometry allows the fin to deliver both high aspect ratio benefits and adequate effective area without requiring a longer shaft.
Data Source
Figure 1~2
Figure 3~5
AI summary
The apparatus has fin (5) that is moved from operating position into rest position to accommodate pocket (2) pivoted within the ship. The fin is formed as an elongated rectangle such that short side in operating position is parallel to the ship outer hull (1) and long side is provided with forward facing angled rearward sweep (10). The axis of fin is in the range 10-30% of an average chord length of the fin located in central span. The tapering of pivotal movement of pivot column (3) from operating position to rest position is greater than 90 [deg] to accommodate the pocket.