Closed Liquid Tank Trim Control for Ballast-Free Transport Ships

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Solution Overview

Problem

Existing ships without seawater ballast face significant navigability issues, including reduced draught, inclination, and waterline lowering, which compromise safety and stability, especially when unladen, and result in ecological and operational inefficiencies.

Innovation Solution

A transport ship design featuring a trapezoidal lower hull with strategically positioned closed liquid tanks and a mooring tank, allowing for controlled liquid transfer to adjust trim and draught, eliminating the need for seawater ballast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If seawater ballast is used to maintain navigability conditions, then draught and stability are improved, but energy consumption increases and ecological harm occurs

Engineering Contradiction:

Improvenavigability conditionsVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention extracts and eliminates the seawater ballast system from the ship, replacing it with a closed-loop liquid transfer system that uses internal liquid redistribution rather than external seawater intake and discharge, thereby eliminating the energy consumption and ecological harm associated with ballast water management

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ship uses its own liquid cargo or internal liquid reserves to adjust trim and draught through controlled transfer between tanks, rather than relying on external seawater ballast systems, making the system self-sufficient and eliminating ecological discharge issues

Inventive Principle:

Principle #25Self-service

2Reliability

If seawater ballast is used to maintain adequate draught, then propulsion screw immersion is improved, but ship speed decreases

Engineering Contradiction:

Improvepropulsion screw immersionVSAvoidship speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention implements dynamic liquid transfer between tanks that can be adjusted in real-time based on ship speed and operational conditions, allowing the ship to maintain adequate draught for propulsion screw immersion while minimizing the drag penalty associated with ballast water, thereby preserving ship speed

Inventive Principle:

Principle #15Dynamics

3Reliability

If seawater ballast is used to correct trim imbalance, then stability is improved, but operational complexity increases

Engineering Contradiction:

ImprovestabilityVSAvoidballast system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the trim correction function with the existing cargo tank system by using the same liquid cargo or internal reserves for both propulsion and trim adjustment, eliminating the need for separate seawater ballast tanks and associated complex pumping and valve systems

Inventive Principle:

Principle #5Merging (Combining)

4Quantity of substance

If ship design accommodates large cargo capacity, then loading capacity is improved, but unladen draught reduction worsens

Engineering Contradiction:

Improvecargo capacityVSAvoidunladen draught

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The invention divides the ship's liquid storage into multiple segregated tanks with independent transfer capability, allowing strategic placement of liquid mass in forward tanks to maintain adequate bow immersion and draught when the ship is unladen, while preserving full cargo capacity when loaded

Inventive Principle:

Principle #1Segmentation

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

Enhances navigability and stability, reduces energy consumption, minimizes ecological impact, and simplifies port maneuvers by maintaining optimal waterline and trim without the drawbacks of seawater ballast.

Implementation Method 1

said tanks being in communication via at least one line for the transfer of liquid from one to the other

Methodology Applied

Scientific EffectLiquid transfer:

Implementation Method 2

said mooring tank being arranged at the bow of the ship so that supplying liquid to said mooring tank enables correction of the trim of the ship

Methodology Applied

Scientific EffectLiquid transfer for trim correction:

Implementation Method 3

a lower hull a cross section of which takes the form of a trapezium comprising a part forming a flat bottom of the ship from which respectively extend two flanks of identical inclination

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentUS12600444B2Method for controlling the trim of a transport ship without seawater ballast

Publication Date: 2026.04.14 GAZTRANSPORT & TECHNIGAZ SA

AI summary

The present invention concerns a method for controlling the trim of a transport ship without seawater ballast (1), having a width l considered along a transverse axis (y′y) of the ship (1), said ship (1) having an unladen weight Pv between 20% and 60% inclusive of its total weight PT, allowing for a given maximum load weight capacity PTC, in accordance with the formula:PT=Pv+PTC at least one first and one second closed liquid tank (3′ or 3″) not communicating with the sea, the total weight PRT of which when entirely filled with a liquid of specific gravity equal to 1 represents between 2% and 8%, preferably between 3% and 6%, of said unladen weight PV, said tanks (3′, 3″) being in communication via at least one line to transfer liquid from one to the other and being at a distance d from one another, considering the respective geometric center of each of said tanks (3″, 3″), at least equal to ½ when the tanks (3′, 3″) are positioned facing one another essentially along the transverse axis (y′y): d≥½.