Bidirectional Trim Tab Pivoting for Vessel Stern Drag

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Solution Overview

Problem

Standard trim tabs are unable to lower the stern of a vessel, which is desirable in certain situations such as when pulling a water skier, as they are designed to rotate from zero to approximately 45° to adjust the vessel upward for planing, but not to create stern drag by ploughing into the water.

Innovation Solution

A dual rotation trim tab apparatus that can pivot both upward and downward, with a flat trim plane pivotally attached to arms fixed to the vessel, allowing the stern to be adjusted either upward or downward, creating lift or drag as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If standard trim tabs are designed to rotate from zero to approximately 45° to adjust the vessel upward for planing, then the vessel can be trimmed to plane the hull parallel to the water surface, but the stern cannot be lowered into the water to create stern drag

Engineering Contradiction:

Improvevessel trim adjustment capabilityVSAvoidstern drag creation capability

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The trim tab is designed to pivot in both directions from a neutral position: upward rotation (0° to 45°) creates stern lift for planing, while downward rotation creates stern drag by plowing into the water. This bidirectional pivoting capability allows the same device to perform opposite functions, resolving the contradiction between upward trim adjustment and downward stern positioning.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The trim tab apparatus serves multiple functions: it can raise the stern for planing operations, lower the stern for water skiing starts, and maintain a neutral position. This multi-functionality is achieved through the dual-directional pivoting mechanism that allows the trim tab to deflect in both upward and downward directions, making a single device adaptable to different operational requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If trim tabs are designed for upward rotation only, then the structure can be simple and straightforward, but the device cannot perform dual rotation to create both lift and drag

Engineering Contradiction:

Improvetrim tab structureVSAvoiddual rotation capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The trim tab is designed as a dynamic component that can change its orientation in both directions from a neutral position. The pivoting mechanism allows the trim tab to adapt its angle dynamically - rotating upward for lift, downward for drag, and returning to neutral. This dynamic capability is achieved through a straightforward pivot connection that permits bidirectional movement without complex mechanisms.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If the trim tab pivots downward to lower the stern, then stern drag is created for water skiing, but the ability to raise the stern for planing is lost

Engineering Contradiction:

Improvestern drag functionVSAvoidstern lift function

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The trim tab utilizes symmetric bidirectional pivoting where the downward deflection angle mirrors the upward deflection angle capability. This allows the device to create stern drag by pivoting downward while maintaining the ability to pivot upward for stern lift. The neutral position serves as the reference point from which both upward and downward rotations are measured, ensuring equal capability in both directions.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Enables the stern of the vessel to be lowered into the water, increasing stern drag, providing improved control and maneuverability during water sports by creating sufficient resistance to pull the stern below the water surface.

Implementation Method 1

When deflected downward, the water force on the trim tab creates upward pressure, raising the stern

Methodology Applied

Scientific EffectWater force deflection: Fluid Spray

Implementation Method 2

when the fore end is pivoted downward, there is sufficient resistance, or 'stern drag' created as it ploughs into the water

Methodology Applied

Scientific EffectDrag: Drag

Data Source

PatentUS8251006B2Vessel trim-tabs with pivotal connection

Publication Date: 2012.08.28 ANTHONY KALIL

AI summary

A trim tab apparatus capable of causing the stern of a vessel to be raised or lowered relative to the surface of the water in which it rests. A trim tab plane can be pivotally attached to one or more arms that can be attached to a vessel by one or more brackets. When the trim tab plane is rotated in an aft direction as a vessel is moving, the force of water passing under the trim tab plane causes the vessel stern to be raised. If the trim tab planes are rotated in a fore direction as the vessel is moving, water is forced across the top of the trim tab planes causing stern-drag, so that the vessel stern is lowered in the water.