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Ship trials provide a very important source of information for solution of different tasks of maneuverability of ships. This paper is devoted to the consideration of two such tasks: definition of the maneuverability criteria and determination of the hydrodynamic characteristics of the ship's hull. A set of criteria based on determining parameters of ship maneuvering is considered. A method is presented for the determination of hydrodynamic characteristics of a ship hull from the parameters of motion measured during the maneuvering trials. This method is based on the results of the analysis of the relationship between the hydrodynamic forces on the ship hull and rudder. The hydrodynamic characteristics of the ship hull determined from the trials can be used for new designs, in the study of scale effects, and other tasks of the applied maneuverability of ships.
- Transportation > Marine (0.89)
- Shipbuilding (0.89)
Critical Needs for Ship Maneuverability: Lessons From the Houston Ship Channel Full-Scale Maneuvering Trials
Landsburg, Alexander C. (United States Maritime Administration) | Barr, Roderick A. (Hydronautics Research, Inc) | Daggett, Larry (Waterway Simulation Technology, Inc.) | Hwang, Wei-Yuan (United States Merchant Marine Academy) | Jakobsen, Bent (Computer Science Corporation) | Morris, Mike (Houston Pilots Association) | Vest, Lou (Houston Pilots Association)
"I think the architects and engineers that design ships for the sea, where they spend 99% of their time, forget that at some point they still have to get up the ditches to load or discharge their cargo. Someday when a high-profile accident does occur, ship builders might even be brought into the civil arena and found criminally negligent and liable for building underpowered and poor handling ships."A pilot's view The Standards for Ship Maneuverability approved by the International Maritime Organization (IMO) in 2002 represent a significant step forward in ensuring adequate maneuverability of ships. The Standards provide numerical criteria for assessing the adequacy of maneuverability in deep, unrestricted water at sea speed. Explanatory notes to the Standards provide useful guidelines to the assessment and validation process that help with various issues, such as adjusting full-scale trial results for environmental and loading conditions. Major issues exist, however. In question is the ability of the standards to ensure adequate maneuverability in shallow, restricted, and congested waterways under vessel meeting and passing conditions with the interaction effects, bank suction, and other situations that are encountered in normal port, harbor, and waterway operations. Historically, even in shallow water that is unrestricted, only a couple of ship trials have ever been conducted due to the great cost to prepare for such tests. The lack of accurate full-scale data has seriously limited the accuracy capable of being built into mathematical prediction models. Recently, however, revolutionary positioning technology has enabled collecting highly accurate track and vertical position data on ships operating in shallow and restricted water, with and without interacting ship traffic. Accurate mathematical modeling of ship operations in complex harbors and waterways has become a critical need, and now the possibility of advancing the science finally exists. With accurate full-scale trials data and improved prediction techniques, such as computational fluid dynamics, such ability now seems attainable.
- Transportation > Marine (1.00)
- Transportation > Freight & Logistics Services > Shipping (1.00)
- Government > Regional Government > North America Government > United States Government (1.00)
Experimental Investigation of the Hydrodynamic Force Acting on Ship Hull and Rudder in Various Wave Direction
Nguyen, Van Minh (Changwon National University) | Nguyen, Tien Thua (Changwon National University) | Seo, Juwon (Changwon National University) | Yoon, Hyeon Kyu (Changwon National University) | Kim, Yeon Gyu (Korea Research Institute of Ships & Ocean Engineering)
ABSTRACT In the past, traditional methods of research on ship maneuvering performance were estimated in calm waters. However, the course-keeping ability and the maneuvering performance of a ship can be influenced by the presence of waves. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves. In this paper, the prediction force acting on the rudder in calm waters was carried out and compared with those of CFD. Model test in regular wave was performed to predict the force acting on the ship and the rudder behind the model ship in various wave directions. INTRODUCTION In the past, traditional methods of research on ship maneuvering performance was estimated in calm waters conditions was not associated with seakeeping performance. The course-keeping ability and the maneuvering performance of a ship can be dramatically affected by the real sea condition. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves in the viewpoint of ship safety in the design stage. According to ITTC (2008), the ship maneuverability in waves is of vital importance for navigation safety of seagoing ships. Various researchers have investigated the maneuverability of a ship in waves. Adnan and Yasukawa (2006) measured the added resistance, steady drifting lateral force and yaw moment acting on an obliquely moving ship in regular waves using the S-175 container ship model. Xu et al. (2007) conducted an experimental research on ship maneuverability in waves which included a series of a Planar Motion Mechanism (PMM) tests in waves to measure the forces on the model. Skejic et al. (2008) developed the unified theory of seakeeping and maneuverability of ships in regular waves. Seo and Kim (2011) explored the numerical analysis on ship maneuvering coupled with ship motion in waves. These researchers only mentioned the ship maneuverability in waves in the case of head sea, and beam sea, but they did not evaluate the influence of incident wave which poses the real challenge in the maneuverability of the ship. In this study, the force and yaw moment acting on a moving ship in regular waves with different wavelength and wave direction was performed in the square wave tank in Changwon National University (CWNU). First, experiments on forces and moment were conducted in waves and calm waters using the KCS container ship model. In addition, to verify the force acting on the rudder in calm waters, the comparison of the experiment of force acting on the rudder in calm waters between EFD and CFD was carried out. Second, forces and moment were obtained by subtracting the experiment results in waves from the results obtained in calm waters. Finally, the effect of wavelength and wave direction on the forces and moments acting on the ship hull was discussed. The force and yawing moment acting on the rudder behind KCS model versus rudder angle in various wave directions were investigated in detail.
- Transportation > Marine (1.00)
- Energy > Oil & Gas > Upstream (0.34)
Simulation Study on the Maneuverability of Twin-Propeller Twin-Rudder Bulk Carrier in Large Artificial Waterway
Yue, Pengfei (Wuhan University of Technology) | Wang, Lizheng (Wuhan University of Technology) | Chen, Shunhuai (Wuhan University of Technology) | Jin, Yan (Wuhan University of Technology)
ABSTRACT With the new situation of inland ships maximization, the ship maneuvering is becoming more dangerous in restricted water. In this paper, a twin-propeller twin-rudder bulk carrier was chosen as the research object to study on the ship maneuverability in large artificial waterway. Firstly, 3 degrees of freedom (3-DOF) practical Maneuvering Modeling Group (MMG) ship mathematic model was carried out and was verified by the ship model test. Then the influence factors of bulk carrier maneuverability due to the bank effect were investigated through maneuvering simulation. Finally, the fuzzy adaptive PID control was used to ensure the ship course stability. The result is shown as follows: the distance off centerline and the ratio of water depth to draft (h/d) has significant effect on ship maneuvering. The effect of the waterway slope angle was less, and the ship speed had minimal impact on ship maneuvering. And a regression formula of maximum distance close to the bank was fitted. In addition, the fuzzy adaptive PID control could correct course deviation due to the bank effect, keep course steady quickly. INTRODUCTION In recent years, the freight volume of the Yangtze River increases rapidly. The problem of blockage becomes more serious in the middle reaches of the Yangtze River. As shown in Fig. 1, the middle Yangtze River (highlighted in red), with a depth no more than 4m, restricts the ships maximization. To solve this problem, a large artificial waterway, with the width of 138m, is being constructed in Yangtze River (Zhang, 2018). The artificial waterway is a typically restricted water area. Ship maneuvering in the artificial waterway is affected by the bank effect and shallow water effect. Under the bank effect, the ship bow will be pushed away by the bank, and the ship body will be attracted towards the bank. The shallow water will aggravate the bank effect and restrict maneuvering. These effects make ships difficult to control, even could lead to marine accidents like collision and grounding. In order to ensure the safety of ship maneuvering, it is particularly important to investigate ship maneuvering in large artificial waterway.
- Transportation > Marine (1.00)
- Transportation > Freight & Logistics Services > Shipping > Dry Bulk Carrier (0.81)
Abstract A short abstract (50 to 100 words) in a single paragraph should be included here. In this paper, a comprehensive mathematical model for integrated optimization of UUV is proposed, based on the flat UUV structure and adequate analysis of UUV performance (mainly resistance and propulsion performance, horizontal and vertical movement performance). The genetic algorithm is incorporated with parallel strategies, which forms the parallel genetic algorithm (PGA). The UUV integrated optimization program is written via C++ by integrating the comprehensive mathematical model with PGA. In addition, the effect of using different whole objective functions has been analyzed, and the optimal whole objective function has been presented in this paper.