Sharif Digital Repository

Performing research and development in the field of modern vessel types which serve several functions is considerably necessary because of their importance and rapid development. HARTH vessel is considered one of the important ships which has been recently attracted much attention from the world. In this respect, a full investigation of its performance could make a big contribution to its optimum design and appropriate exploitation.“HARTH” ship is the abbreviation for “High Aspect Ratio Twin Hull” is included in the catamaran vessel category with a high aspect ratio with respect to their underwater cross-section’s ratio of length to width.A host of crucial issues should be considered for... 

Regarding the increasing application of fast boats in the world, studying the dynamic performances of these boats is consequently effective and vital. So one can evaluate the hull performance in different sea forces. Vast activities take place in all over the world yearly. General performances hull tests occur in marine laboratories such as Wave maker and carriage. Model hull test is one of effective branches of the naval architecture engineering. This method is also based on dimensional analysis. In this thesis, after understanding the waves and the methodology some experimental tests are done in the conditions of frontal static waves, and heave, pitch and roll activities of the craft are... 

In the ship designing, it is preferable to access to a good performance in waves and low efficiency loss. Accordingly, modeling and estimation of added resistance would be an important issue. Added resistance in wave is an important part of ship's performance due to many technical and economic effects on the ship's performance. With understanding and awareness of the added resistance that comes from ship accident to the waves, we can reduce this parameter by changing in specifications and hull form of ships. Designers are also interested in optimizing the ship from this aspect. In previous works, added resistance in waves was obtained from experimental, numerical and analytical methods. In... 

In this thesis, an attempt is made to provide a hydro-aerodynamic mathematical model of a 20-bird batboat with a combined wing with catamaran body shape equipped with a parachute propulsion system in the rising phase of the surface and optimizing the propulsion system to reduce the take-off phase of the bird's boat. For this purpose, the hydro-aerodynamic modeling of the bird's boat from the rest period to the cruise phase has been considered, taking into account the parachuting system. For this purpose, three methods are considered. In the first method, combinatorial wing aerodynamic modeling and hydrodynamic modeling of the radar catamaran float were first studied. Finally, in the case of... 

Dynamics modeling of high speed crafts in waves is one of the major problems in design precess. Mathematical models compared with other methods have lower cost for studying behavior of ships in waves. On the other hand, experimental methods may also be suitable for various problems. Due to nonlinear behavior of high speed crafts, dynamics modeling of these vessels will be. Combination of experimental and mathematical models to predict the precise dynamics of high speed craft in wave is a suitable method. In this study, a nonlinear method is used for predicting the motions of vessels in waves. In this method, nonlinear time domain behavior of vessel is studied. At first a monohull vessel... 

Properly adjusting the trim angle during the craft speed up will be extremely important in special cases as in sport competitions or military missions. In such applications, the goal of trim adjustment is to reach final speed in a minimum possible time which is an advantage to just passing the resistance hump. Present study tries to provide insight into how the concerned control variables such as angles of the drive system and trim tab of a planing craft should be changed during acceleration mode so as to minimize the time needed to reach the final speed. This is a time-optimal control problem. Optimal control theory has been used previously for the motion control of marine vessels in... 

The turbulent waves of the sea and their impact have always been one of the challenges of marine activities. Recently, with the world economic development and the boom of maritime tourism, providing comfort for the occupants of ships and boats has become one of the issues of engineering concern. Therefore, different methods are used to address this challenge. In this article, we first review these methods and then try to choose the optimal method and design a system for a relatively small boat that can compete with other methods. The method of choice is "damping mass", which has never been used to reduce the movement of boats. In this paper, by obtaining the equations governing the physics... 

Planing crafts in waves are characterized by large and violent vertical motion and acceleration. The hull structure is subjected to high impact loads and the crew experiences high transient vertical acceleration and in most cases the crew needs to lower speed in order to avoid damage to the hull.In recent years, interest on increasingly faster marine vehicles has remarkably grown. Typical planing monohulls are: patrol vessels, pilot boats, rescue vessels, coast guard vessels and small navy vessels. So the behavior of planing monohulls in waves has been a widely researched topic since more and more planing monohulls appeared.The accurate prediction of large amplitude ship motions in severe... 

Increasing the speed of marine transportation services for specific mission and rapidly movement of persons or product always have been considered major issue in maritime industry. In recent years different technology have been used by high speed vessels manufacturer for increasing the safety of crew and passengers at sea. Catamaran is one of the most important high speed craft in marine transportation industry. High speed catamaran nonlinear behavior in high velocity is causing longitudinal instability and large motions. Active control surfaces like hydrofoil and interceptor can be used for reducing high speed catamaran motions in waves. This control surfaces react an adequate action... 

One of the reducing and controlling tools of high speed crafts is intelligent interceptor. Interceptor is a small blade that is originally installed vertically in stern. This blade creates a high pressure area under hull of the craft and produces lift force and a moment to the bow. The amount of lift force and moment can be changed by controlling the height of the blade. The intelligent interceptor (with automatic change in height of the blade) does the same thing. In this study, structural and software design of intelligent interceptor is done. In software field, optimal and PID controller are designed for interceptor system and the performances are studied in MATLAB SimuLink. The results... 

In recent years, planing boats have been used in more exposed areas, for instance as patrol boats, pilot boats, coast guard and small naval vessels. When such a small vessel operating in a rough-water environment, frequently experiences violent motions and vertical acceleration. Even on calm water, porpoising may occur and may be severe as the speed is increased. Operation of the crew, equipments and overall operability of the vessel always suffer from mentioned motions. In the present study, the impact of fixed and controlled interceptors on a planing crafts hydrodynamic and seakeeping quality is investigated through application of an experimental and theoretical methods. Two scaled-down... 

The purpose of this study is extracting a dynamic model of longitudinal motions of high speed catamaran in regular and irregular waves, and then motion control of vessels by using of foil control elements and interceptor. For simulating longitudinal motions in regular waves, at first the longitudinal hydrodynamic coefficients of vessels should be extracted, then by substituting extracted coefficients in cumminz equation and using system identification methods, some equations are presented to estimate longitudinal two degree of freedom motions of high speed catamaran in waves. In this thesis the extraction of hydrodynamic coefficients is based on both numerical and experimental methods. ANSYS... 

An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap which can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high speed marine vehicle equipped with aerodynamic surfaces (called a Flying Boat, 'Aerodynamically Alleviated Marine Vehicle') is one such concept. The purpose of this thesis is to evaluate the performance of a Flying Boat before take-off in head sea condition. First, performance will be assessed in calm water, and then will be evaluated in waves. Performance is defined as the variation of Resistance Force and Trim Angle of a vessel in an arbitrary interval. This... 

Planing hulls have been under rapid development during recent years and their maximum speed has increased significantly thanks to advancements in high power engines and light weight hull construction methods. In the past two decades, the main concern have been hydrodynamic characteristics and stability of the planing hulls in straight-line motion in calm and rough water, and no applied mathematical model is proposed for their dynamic motions in different maneuvers in contrast to displacement hulls. Moreover, control loss at high speeds is very prevalent and in most cases this leads to economy and human losses. The main target of this thesis is to develop and validate a mathematical model to... 

In this thesis attempted to present practical hydro-aerodynanic model with low computational time and high accuracy for WIG craft with a compound wing, a catamaran hull form and a power augmented ram (PAR) platform at take-off phase. To achieve this innovation, aerodynamic and hudrodynamic model are coupled and dynamic air cushion between demi hull of catamaran under the wing was considered by modeling PAR platform with effect of flap. To validaty the results of hydro-aerodynanic model, two test models were producted and the results of hydro-aerodynanic model are compared with the experimental results that the presented results had good agreement with the experimental results. Influence of... 

Partially submerged propellers are new type of propellers which knowledges ragard them is limited. These propellers found a growing market ahead of them and expertsexpect to use these propellers for big vessels at high speeds. This type of propulsors do not lose their efficiences at high speeds and are assumped to be economical. Meanwhile due to continuosus hit to water surface, huge stresses are extered on tha blade witch needs to be fundamentally studied. Several researchers have studied the partially submerged propellers which unfortunately did not publish their results. Undergo less or more thrust and torques which in both cases the efficiency also increases. The use of numerical methods... 

In this thesis, the problem of trajectory planning for a high speed planing boat under nonlinear equality and inequality constraints is addressed. First, a nonlinear mathematical model of the craft’s dynamics is derived. To solve a trajectory optimization problem, we can utilize the indirect or direct methods. In the indirect methods, maximum principle of Pontryagin is used to transform the optimal control problem into Euler Lagrange equations, on the other hand, in the direct methods it is necessary to transcribe the optimal control problem into a nonlinear programming problem (NLP) by discretization of states and controls. The resulted NLP can be solved by well-developed algorithms such as... 

In recent years design and manufacturing of high speed marine vessels has been developed. to estimate and control dynamics of these vessels the dynamic equation is needed.The aim of this research is Determination of hydrodynamic and aerodynamic coefficients and longitudinal dynamic equation of a high speed catamaran wich is a kind of AAMV. There are three ways to determine these coefficients. Analytical method which is usually not applicable for industrial problems, Experimental method which is too expensive and numerical method which have two parts. The first is softwares that analyse the flow with assumption that the fluid is inviscid and second softwares which solve the full Navier-Stokes... 

The current research is one of the sections of the project for the design and construction of an Unmanned Surface vehicle (USV) , with the goal of extracting the dynamic model of the float using experimental tests. Initially, a literature review on system identification methods and the development of a dynamic model of the float has been conducted. Following that, the process of constructing and equipping a Catamaran platform for conducting tests and collecting suitable data for extracting the dynamic model has been described. Subsequently, tests have been conducted on the constructed float.Using the data obtained from the experimental tests, an artificial neural network has been employed to...