External Hydraulic Fin Stabilizer Without Rotating Hull Seals
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Solution Overview
Problem
Traditional fin roll stabilizers for marine vessels require internal mechanisms that occupy space, generate noise, and necessitate frequent seal replacements due to seawater ingress, compromising hull integrity.
Innovation Solution
The stabilizer mechanism is housed externally, with a fixed connector on the hull and a rotating external effector, utilizing hydraulic actuators and motors outside the vessel, eliminating the need for internal components and rotating seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stabilizer mechanism is mounted inside the vessel using internal hydraulic cylinders or electric motors, then the stabilizer can provide effective roll reduction, but the mechanism occupies valuable interior space and generates noise
Solution Approach 1:
The patent extracts the hydraulic actuator and mechanism from the vessel interior and relocates it to the exterior, mounting the actuator on the outside of the hull. This eliminates the space occupation and noise generation inside the vessel while preserving the stabilizer's roll reduction effectiveness through external placement of the same functional components.
2Ease of operation
If a rotating shaft penetrates the hull to drive the fin, then the fin can be rotated effectively, but flexible seals are required that are subject to wear and compromise watertight integrity
Solution Approach 1:
The patent eliminates the rotating shaft penetration through the hull by extracting this component from the design. Instead, the fin is rotated by a vane actuated by hydraulic pressure applied to the external side of the fin, with the hydraulic actuator mounted outside the hull. This removes the need for flexible seals and rotating connections through the hull, maintaining watertight integrity while preserving fin rotation capability.
Solution Approach 2:
The patent replaces the mechanical rotating shaft and flexible seal system with a hydraulic actuation system. Hydraulic pressure is applied to a vane on the external side of the fin to rotate it, eliminating the need for mechanical connections through the hull and the associated sealing requirements.
3Ease of operation
If high power electrical equipment is positioned outside the vessel hull, then the actuator can be located externally, but electrical equipment may become wet and cause an electrical short
Solution Approach 1:
The patent replaces electrical motors with a hydraulic actuation system for the external actuator. Hydraulic pressure is used to actuate the vane and rotate the fin, eliminating high power electrical equipment from the external environment. This maintains external positioning benefits while avoiding electrical short risks, as hydraulic systems are inherently more resistant to water exposure.
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 design reduces noise, saves space, and enhances hull integrity by eliminating the need for internal mechanisms and rotating seals, while allowing for efficient stabilization without the drawbacks of traditional systems.
Implementation Method 1
One or more internal hydraulic motors rotate the bearing structure about the fixed connector/shaft. In some cases, no motor is provided within the external effector, rather an actuator is provided and the shaft includes passageways for hydraulic fluid to flow to thereby manipulate the actuator and external effector.
Implementation Method 2
The external effector's axis of rotation is provided by a bearing and/or bushing support structure inside the external effector.
Implementation Method 3
Underway, the relative movement of water means smaller angle changes are needed since lift can be generated based on the movement of the water over the fin.
Implementation Method 4
When the vessel is at rest (e.g. at anchor), the fins can operate through larger angle ranges to generate paddle force to reduce roll at anchor.
Data Source
Figure 1~2
Figure 3~4B
Figure 5~7
AI summary
A fin stabilizer is provided for a vessel and includes a fin which is supported by a shaft that extends below the waterline. The shaft is fixed in rotation along its elongate axis relative to the vessel and the fin includes an actuator mechanism which causes the fin to rotate around the shaft to counteract roll of the vessel. In some cases, the actuator may be hydraulic and the shaft may include passages therethrough to transfer hydraulic fluid/pressure from the vessel's interior hydraulic system through the shaft and into the actuator to cause the fin to rotate. The fin may also be able to pivot into a storage position where, for example, the shaft is folded into a cavity in the vessel hull.