JP7574514B2 - Ship Stability Control System - Google Patents

Description

The invention relates in the most general sense to a system for stabilization used on ships during loaded operations. The invention mainly concerns a ballast-free system that uses buoys and channels to ensure dynamic control of the ship's stability instantly depending on the loading situation. The absence of ballast tanks ensures that the onboard water does not carry bacteria, viruses and many other larval and developing sea creatures to the new marine ecosystem.

There are two main forms of wave action that affect all ships: ocean waves, which are created by the force of wind, and ship waves, which are created by the motion of the ship. Ocean waves are undesirable and affect almost all ships. Ship waves, on the other hand, are formed when a ship pushes against the water on the surface while moving. Ocean waves and wind force a ship to heel and roll. Ballast tanks are also used to prevent stability problems due to wave action.

Ballast water is water carried in ballast tanks to ensure stability while a ship is underway. Ships with empty cargo holds (unladen ships) often need to fill lower tanks with ballast to shift the center of gravity. Ballast water can improve both the ship's maneuverability and stress levels by stabilizing the ship. On the other hand, ballast water stored in a ship's ballast tanks has some drawbacks, because the ballast water taken on board may contain bacteria, viruses, and marine organisms in their larval and developmental stages. Despite the process of discharging and taking up ballast, some organisms may survive and be carried to other ecosystems. This situation causes ecological and economic problems and poses a risk to public health.

Ships continue to move billions of tonnes of ballast water around the world every year, despite the known effects on underwater ecosystems. Some organisms in ballast water die due to temperature changes in the ballast water, lack of food and the lack of light during the ship's journey. However, some resistant organisms survive and blend into the new marine ecosystems they arrive in, where they can overtake natural habitats and become invasive species. Marine ecosystems are under great threat as a result of ships moving microorganisms from their ballast tanks to new environments.

Some improvements have been made to prevent the disadvantages of ballast water, but more is needed. The International Maritime Organization (IMO) developed the "International Convention for the Control and Management of Ships' Ballast Water and Sediments" to prevent the spread of microorganisms through ballast water. The agreement was signed by many countries in 2004. Under the agreement, ships are required to treat their ballast water and to carry out ballast water analysis to ensure its compatibility before ballast water exchange. However, as a result of the mandatory analysis, treatment and management of ballast water, this preventative measure requires extra costs and effort.

Currently, the disadvantages of the ballast system used on ships are known, so some improvements are being made to solve these problems. The first of these improvements is the adoption of ballast-free ships. Ballast-free ship models do not have extra piping and pumps for ballast tanks on board, and by not having tanks, maintenance costs can be reduced. This system is characterized by a hollow space or waterway called a "trunk" under the keel of the ship. Water flows constantly through this trunk, which acts as the ship's ballast system. However, this system has many disadvantages. As water continues to flow through the waterway, the center of buoyancy of the ship always moves from the stern to the bow, compromising the stability of the ship. Another disadvantage is that the size of the ship is limited. With a ship without ballast tanks, the ship needs to be made larger in width rather than in length in order to ensure the same amount of cargo without compromising stability. However, this method leads to an increase in the construction cost of the ship. Therefore, it is necessary to develop a new system that can control the water entering the waterway with a buoy-like mechanism for stabilization operations.

The article "Revisiting the hydrodynamics of ballast-free ships" describes how to prevent the transport of harmful species through ballast tanks, avoid increasing hull resistance at the ship's operating speed, and ensure trim, heel, and stability control in all sea conditions. To achieve these goals, valves at the entrance and exit of the channel open and close depending on the stability of the ship. Depending on the ship's speed, seawater enters the channel entrance and leaves the channel exit. The opening and closing of the valves fills a tank with a certain volume of water. Leaving the outflow valve open allows the water to flow out, preventing harmful species from attaching and being transported to various locations. New technologies are needed to maintain the stability of the ship without adding additional valves. This can be achieved with buoy-like structures placed along the sides of the ship's hull to maintain weight stability. Existing solutions in the art have several problems and limitations, which require innovation.

The patent application "KR20150062310A" proposes a system that floats the cargo hold inside the ship's hull while keeping the ship's weight and volume stable, eliminating the need for ballast tanks and preventing the transport of dangerous species. However, this system is not suitable for transporting heavy cargo such as ores, and may be dangerous for safe navigation under severe sea conditions. Therefore, a new technology is needed that can transport dangerous species without reducing the transport efficiency of cargoes with different densities and weights. The technology also needs to address issues such as correcting trim and inclination, maintaining the longitudinal strength of large commercial ships, reducing operation and manufacturing costs, blocking water currents and ensuring stability.

Another patent application in this field, US4528927A, is for a high-speed boat that uses hydrodynamic buoyancy in addition to hydrostatic buoyancy to achieve high speeds. However, this system can cause the bow to lift excessively during rapid acceleration or high speeds, pointing out the need for new technology to improve the longitudinal strength of large commercial ships against trim and heel caused by loading and unloading.

As a result, the above shortcomings and the inadequacies of existing solutions to this problem have created a need for developments in related technology areas to correct the trim and heel caused by loading and unloading of large commercial ships, prevent ecosystem degradation due to shifts in the habitats of many marine organisms, including bacteria and viruses, reduce production and operating costs, ensure uninterrupted water flow, and maintain stability.

The most important objective of the present invention is to limit and control the pollution caused by ships. The proposed system ensures that ecological transport, which transports different organisms present in the water added to the sea by the ballasting operation of the ship, is prevented.

Another object of the present invention is to prevent marine organisms such as bacteria and viruses from being carried to the wall by water currents during navigation, thereby preventing the deterioration of the ecosystem balance.

Another object of the invention is to meet the requirements of the International Maritime Organization's Ballast Water Management System by not bringing seawater on board the ship.

Another object of the invention is to provide different loading scenarios. To this end, the system allows the buoy to be moved vertically in increments.

Another objective of the present invention is to develop a system with low operating costs. The system does not have pumps, opening and closing hatches, or other parts that are prone to failure. In addition, the waterway entrance is located at the bow and the waterway exit is located at the stern, ensuring a continuous flow and providing a natural flow according to the pressure distribution on the hull surface.

Furthermore, it is also an object to change the amount of seawater that can enter in order to keep the stability of the hull. For this purpose, there are buoys inside the ship that can move up and down. By gradually moving up and down, the volume that can receive the required seawater can be changed. This makes it possible to change the stability of the ship accordingly to accommodate different loading situations. Also, since the buoys are inside the hull, it is possible to prevent an excessive increase in resistance values due to the hydrodynamic design of the surface of the hull. Also, the influence of pressure values on the place where the buoys are installed is reduced. Providing stability of the ship is another object of the proposed invention. Even when all the buoys are in the top position, i.e. when the volume that can be filled with seawater is maximum, it has an additional reserve volume at large angles in extreme roll movements. In other words, even if the chamber (6) is completely filled with seawater, additional reserve volume can be provided thanks to the buoys. This situation is beneficial in terms of stability, since it is possible to increase the maximum angle at which stability disappears.

Another object of the present invention is to reduce ocean wave loads and wave resistance of a ship.

Diagram of the system for stabilizing the ship's hull under loading conditions Diagram of cargo compartment, hull and buoy in loaded condition Diagram of cargo compartment, hull and buoy in loaded condition Diagram of the up and down movement of the buoy under loaded conditions Diagram of the volume filled with seawater under loaded conditions and the buoy moving up and down Diagram showing how stability control is performed in a volume filled with seawater in a system related to ensuring the stability of the hull under loading conditions of a ship.

Equivalent to the numerical values shown in the figure.
1. Hull 2. Cargo compartment 3. Buoy 4. Waterway through the hull 5. Waterway through the buoy 6. Chamber 7. Waterway entrance 8. Waterway exit

The present invention proposes a system for stabilizing a ship's hull (1) under loading conditions on a vessel. In particular, the present invention proposes a system using buoys and channels for stability control on a vessel, without ballast tanks.

Various cargoes are placed in the cargo hold (2) of the ship depending on the loading operation. This situation shifts the ship's center of gravity, which results in the ship trimming and/or heeling. The moment required to return the hull (1) to a stable position is provided by multiple chambers (6) that are filled with seawater by the up and down movement of multiple buoys (3). The use of buoys (3) that move up and down on the ship makes the use of ballast tanks unnecessary. In this way, dangerous marine life is prevented from being transported to different locations using ballast tanks.

Inside the hull (1), there are multiple water channels (4) for circulating seawater that extend from the forequarter (front of the hull) to the aft quarter (rear of the hull). The seawater required for seawater circulation is supplied through a water channel inlet (7) installed in the forequarter. In order for seawater to circulate, it is necessary to be able to discharge the seawater from a water channel outlet (8) located in the aft quarter.

When a ship is sailing, the pressure distribution on the surface of the hull changes. The difference between the positive pressure at the bow, where the channel inlet (7) is located, and the negative pressure at the stern, where the channel outlet (8) is located, creates a flow in the channel. Thanks to this water flow, dangerous species can be prevented from being transported to different areas. To prevent the flow of seawater from being obstructed by the change in position of the buoy (3) as it moves up and down, there is a channel (5) that passes through the buoy (3) to match the channel (4) that passes through the hull. The volume of the ship that provides hydrostatic lift, i.e. the chamber (6) filled with seawater, can be adjusted by moving the buoy (3). The movement of the buoy allows adjustment according to the height and position of the center of gravity. It also provides additional volume against excessive roll movements, increasing the roll angle of the ship.

This system is equipped with a waterway (4) that passes through the hull and a waterway (5) that passes through the buoy, where water currents are generated while the ship is moving, and a buoy (3) that is installed continuously on the inner wall and can move in the vertical direction. This prevents the water currents from carrying bacteria, viruses, and other marine life on the inner wall while the ship is sailing, and prevents the stability of the ecosystem from deteriorating.

Furthermore, there are many holds separated by transverse bulkheads along the ship, and cargoes of different densities or weights may be carried in these holds. Trim and heeling can be controlled by the conditioning chambers (6) that are filled with seawater in the proposed system, since the transportation of cargo loads of different densities in the holds also affects the longitudinal strength of the ship. For this reason, the chambers (6) filled with seawater need to be conditioned by the movement of the buoys (3) so as not to adversely affect the longitudinal strength. As a result, by taking into account the above requirements, the transportation of microorganisms and marine organisms living in different regions and the invasion of marine areas by these organisms can be prevented.

The stability of a ship is important for the safety of the crew, passengers and cargo. Thanks to the system developed in this invention, the buoy (3) moving on the longitudinal axis provides sufficient volume for stability control, allowing the ship to navigate safely and stably under all sea conditions. Also, even if the buoy (3) system fails in the event of excessive heeling, there is a reserve volume that is important for the stability of the ship, because even if the chamber (6) filled with seawater is completely filled in order to increase the vanishing angle of stability, a reserve volume is formed thanks to the buoy (3). This means that the safety of the ship can be increased.

To travel the same distance with less fuel, the hydrodynamic design of the ship must be at an optimal level. However, it is preferable for the ship to sail without trimming, since a ship trimmed at the stern and trimmed at the bow due to the weight of the main engines, especially while there is little cargo, is an unfavourable maritime situation. Thanks to the system developed in this invention, fuel savings are achieved by preventing an increase in the ship's resistance.

The proposed system reduces both production and operational costs as no extra ballast tanks and valve-waterway configurations are required. It also reduces costs as no maintenance costs are incurred over a period of time for ballast tanks and valve-waterway configurations.

Claims (2)

1. A vessel stabilization system for providing stability to a vessel when loaded, comprising:
- a buoy (3) located on the side of the ship, which moves up and down to bring the hull (1) into a stable position, thereby applying a moment to the hull by filling a number of chambers (6) with seawater, and which is arranged in succession on the inner wall and can move up and down along its longitudinal axis;
- several water channels (4) for the circulation of seawater inside the hull (1), extending from bow to stern;
- several water channels (5) passing through the buoy (3) located to coincide with the water channels (4) passing through the hull of the ship in order to prevent the flow of seawater from being obstructed by changes in position due to the up and down movement of the buoy (3);
- a waterway inlet (7) installed in the forequarter of the ship's hull and providing for the reception and circulation of seawater together with a waterway outlet (8) installed in the aftquarter;
- a channel outlet (8) installed in the aft quarter of the ship's hull and which, together with the channel inlet (7) installed in the forequarter, provides for the reception and circulation of seawater;
1. A vessel stabilization system comprising: 2. A vessel stabilization system according to claim 1, characterized in that the chamber (6) is filled with seawater delivered by the buoy (3) to control the trim and heel of the vessel (1).