Search Results (4)

In some ports, there are separate very narrow places between the quays and other navigational obstacles, where the distance between the quays or between the quays and navigational obstacles is very small. Narrow gaps or channels in the water area, where quays are built and ships are berthing, make it difficult for ships to berth at such quays. Accurate knowledge of a ship’s manoeuvrability characteristics, combined with the application of these characteristics in berthing operations and the optimal use of tugboat capabilities, allows for better utilization of restricted port spaces. The article presents a developed ship berthing methodology designed for ship berthing in extremely limited conditions, utilizing the ship’s manoeuvrability capabilities and maximizing the capabilities of tugboats when mooring ships in extremely limited conditions. The developed methodology was tested with real ships and tugboats in specific port conditions and using calibrated simulators, and the results of the experimental research and theoretical calculations are presented in the article as a case study. The research results (methodology) obtained and presented in the article can be applied to any ships and ports, precisely adapting them to specific port situations. The article studies ship manoeuvrability and tugboat capabilities under various hydrometeorological and hydrological conditions, assesses the impact of shallow depths (shallowness), and determines the boundary conditions for ship berthing. Full article

Harbour tugs are usually used to moor ships if large ships do not have their own additional propulsion devices (thrusters). Alternatively, during ship loading operations, ships sometimes have to be transferred from one quay to another, and in some cases, port users (shipping companies or other companies) have to pay for port tug services. In such cases, it is very important to guarantee the safety of shipping during mooring operations and to use tugboats optimally and at the same time reduce the cost of tugboat services for ship operators and other companies. For the optimal use of tugboats, it is very important to accurately estimate the required traction force (bollard pull) of tugboats and their quantity, taking into account the parameters of moored ships, the locations of berths, hydro-meteorological and hydrological conditions, and clearance (the gap between the ship’s hull and the bottom of the water area), in order to guarantee the safety of navigation and not to order an excess of tugboats in terms of their quantity and powers. This article presents a methodology developed for estimating the required bollard pull and the number of tugs, taking into account the parameters of the ship, hydro-meteorological and hydrological conditions, clearance, and the locations of berths. The developed methodology for estimating the number of tugboats and their traction force (bollard pull) was tested in real conditions (with real ships and tugboats) and using a calibrated simulator, and we found that it can be successfully applied in any port or other complex shipping area by adapting it to specific conditions. The developed methodology for calculating the traction power (bollard pull) of tugboats allows us to determine the required traction force of tugboats in advance with sufficient accuracy, achieved by assessing the specific parameters and environmental conditions of the vessel served by tugboats. In the most difficult areas of the port, in terms of the use of tugboats, this methodology allows us to make reasonable decisions regarding the number of tugboats and the traction force (bollard pull) required and at the same time reduces the risk of emergency situations. Full article

The gyrostabilizer produces the anti-roll effect through the precession output moment generated by a high-speed rotating flywheel. As a floating-base multi-body system composed of ship and gyrostabilizer, the recent research that has only focused on the control strategies or multi-body dynamics is obviously not comprehensive. This study presents an adaptive controller based on the variable gain control strategy for a marine gyrostabilizer installed on a port salvage tug. The variable gain control strategy controlled the flywheel precession output moment of the gyrostabilizer and thereby of the precession process, to reduce the ship roll motion effectively. Furthermore, a full-system hydrodynamic model of a gyrostabilizer-ship-wave based on three-dimensional numerical wave flume technology was innovatively established to evaluate its anti-roll performance under irregular wave conditions. The simulation results show that, for the sea state considered, the increase of spin rate of gyrostabilizer flywheel improved the anti-roll effect significantly. The average anti-roll rate of the gyrostabilizer decreased with the increase of significant wave height, wave period and wave encounter angle. Full article

Port tugs are an important element in port activity and navigational safety issues. Port tugs ensure the safety of big ships while they are entering, manoeuvring, mooring and unmooring, and are of huge importance during other port operations. At the same time, optimizing the number of port tugs and tug bollard pull is also important from a port navigational safety and economic point of view. Calculation and evaluation methods of the optimal request for tugs bollard pull, in particular, port operations, are very important in order to guarantee the navigational safety of the port and ships during the main ship operations in the port. This article provides the number of requested port tugs and bollard pull calculation and evaluation methods on the basis of forces and moments acting on ships. On the basis of real ship voyages and manoeuvring at ports data as well as high accuracy simulators, theoretical methods were used, which were followed by our conclusions and recommendations, which can be used by port harbour masters and tug companies. Modern tugs have become an important element and integral part of modern port navigational safety. Such modern port tugs are also used for navigational safety and other important port functions and activities, such as fire protection and search and rescue operations. The optimal number and capacity evaluation of port tugs depending on port capacity and conditions are studied in this article. Full article