Fin Stabilizer Groove and Closing Structure for Lower Water Resistance

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Solution Overview

Problem

Existing fin stabilizers experience increased resistance due to external water flowing into the fin box, which affects the efficiency of the ship.

Innovation Solution

A fin stabilizer design featuring a groove portion recessed in the hull stern side, a closing portion to partition internal and external spaces, and a method for assembling this configuration, including a groove portion forming and fixing step, to reduce water resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the fin box has an opening for the fin to enter and exit, then the fin can be accommodated and deployed, but external water flows into the interior of the fin box causing increased resistance

Engineering Contradiction:

Improvefin deployment capabilityVSAvoidwater resistance

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The fin box internal space is divided into a front region and a rear region by the closing portion. This segmentation allows the front region to remain open for fin deployment while the rear region is closed to prevent water accumulation, thus resolving the contradiction between fin accessibility and water resistance reduction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The closing portion is extracted as a separate component that can be installed into the fin box. This extraction allows the fin box to maintain its original open structure for fin deployment while adding the closing function to eliminate water resistance without modifying the basic fin box design.

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If a closing portion is added to partition the internal space, then water resistance is reduced, but the device complexity increases

Engineering Contradiction:

Improvewater resistanceVSAvoidfin box structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of closing the entire fin box, only the rear region is closed by the closing portion while the front region remains open. This local quality approach applies the closing function only where needed (at the rear) to reduce water resistance while maintaining fin deployment capability at the front, thus minimizing the increase in device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The closing portion acts as an intermediary element that is installed into the fin box to provide the water-blocking function. This intermediary component allows the fin box structure to remain relatively simple while achieving the water resistance reduction goal through the addition of a single functional element.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the groove portion is formed to be recessed deeply, then water flow guidance is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvewater flow resistanceVSAvoidgroove portion fabrication

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The groove portion is pre-formed as a recessed structure in the hull during the shipbuilding process. This preliminary action allows the water flow guidance feature to be integrated into the hull structure itself, reducing the need for separate manufacturing steps and simplifying the overall manufacturing process while still achieving effective water flow control.

Inventive Principle:

Principle #10Preliminary action

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

The design effectively suppresses water resistance, enhancing the efficiency of the ship by guiding external water flow and minimizing pressure rise within the fin box.

Implementation Method 1

a groove portion forming portion that forms a groove portion formed to be recessed with respect to a hull (11) of the ship (1) on the stern side with respect to the fin box (4) and connecting a side-shell plate (14) of the hull (11) and the stern-side wall surface (49)

Methodology Applied

Scientific EffectFluid flow guidance:

Implementation Method 2

a closing portion that partitions the internal space (40) of the fin box (4) and an external space (10) of the hull (11) from each other on the stern side with respect to a turning region (TA) of the fin (3)

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP4699919A1Fin stabilizer, ship, and method for assembling fin stabilizer

Publication Date: 2026.02.25 MITSUBISHI HEAVY IND MARINE MASCH & EQUIP CO LTD

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AI summary

The present invention is a fin stabilizer for suppressing rolling of a ship, the fin stabilizer comprising: a fin that is configured to be turnable around a rotation axis; a fin box that forms an internal space in which the fin is housed, the fin box including an opening for allowing the fin to go in and out of the internal space and a stern-side wall surface that is a wall surface on the stern side of the fin box; a groove part forming part that forms a groove part that is recessed with respect to the hull of the ship on the stern side of the fin box and connects the outer plate of the hull and the stern-side wall surface; and a closing part that partitions the internal space of the fin box and an external space of the hull on the stern side of the turning area of the fin.