Naval Architecture: Geometry, Hydrostatics, Stability, Dynamics, Strength and Economics - A Computer Based Approach Using Excel Spreadsheets with VBA
This book provides comprehensive coverage of the important topics in naval architecture with an emphasis on applications and spreadsheet solutions with VBA code.
The book is a practical reference guide to ship geometry, hydrostatics, stability, global strength and investment analysis during ship acquisition, ship performance and ship operation, intended for deck officers, naval architects, and marine engineers and for professionals working within the shipping and marine engineering sector.
Ship Geometry is the foundation and the most essential part of the ship. The design of a vessel begins with the hull model. Ship hulls have a curved three dimensional surface which has to be represented in two dimensions for many design calculations and production purposes. The geometry of ship hull surfaces are traditional designed and represented by a set of curves, called the ship line planes. The three principal plans made for the construction of a ship are the sheer plan, the body plan and the half-breadth plan. The geometric requirements for ship hull forms are generally related to curves so that curve design of ship lines usually precedes ship surface design. Thus, the ship surfaces progresses from curve design via curve mesh definition to surface generation. When defining a ship hull surface, the main objective therefore is to show how to obtain a faired surface to give the ship its intended hydrostatic, stability, hydrodynamic and other
properties. In this book, we place our main emphasis on methods of curve mesh fairing and surface interpolation using different curve fitting techniques such as Bezier, B-Spline, NURBS and cubic spline.
Ship Hydrostatics lies at the heart of naval architecture, and in fact, hydrostatics is the foundation of the answer to any naval architecture question. The hydrostatics of a hull are completely determined by the lines and interpreting them using simple rules of integration. The resulting analysis is presented in the form of graphs, termed the curves of form. The hydrostatic curves define the properties of the hull at different drafts, and are used for various naval architectural calculations. It is important that the underwater hull form characteristics for different loading conditions are known for the safety and efficiency of the ship. These characteristics are calculated for a number of waterlines covering all possible loading conditions for the particular ship. These waterlines are taken parallel to the baseline but hull form characteristics for different trim conditions can be calculated by some adjustments. The ship is assumed to be stationary in
calm water, hence the calculations are known as the hydrostatic calculations.
Ship Stability analysis follows naturally from the hydrostatic analysis. While hydrostatics can predict initial stability, the goal of the intact stability analysis is to ensure an adequate range and margin of stability. Ship stability is an area of Naval Architecture and ship design that deals with how a ship behaves at sea, both in still water and in waves. Considerations are made as to the center of gravity and center of buoyancy of vessels and how they interact. Intact stability calculations are relatively straightforward and involve taking all the centers of mass of objects on the vessel and the center of buoyancy of the hull. Damaged stability calculations are much more complicated than intact stability. Various computer analysis tools, such as finite element analysis a.o., are often employed because the areas and volumes can quickly become tedious and long to compute using other methods.
Ship Dynamics and Loads are fundamental in ship design, as the wave-induced motions and loads are important parameters to use as loadings for structural analysis. The calculation procedures needed to establish the structural loading generally involve estimation of the sea environmental conditions to be encountered by the vessel, prediction of the response characteristics of the vessel and specification of the criteria used to assess the vessel's behavior. This book describes a method of how to establishing the wave climate, estimating design wave, and selecting and applying a wave theory to determine the hydrodynamic loading, in which knowledge of the surface waves is essential. Then we describe guidelines for determining the loading that a ship structure will experience. The aim is to provide some background information to perform hydrodynamic analysis, to predict ship motion, hull pressure distributions and sea loads for ships moving in waves. The
hydrodynamic analysis includes determine ship motion in all six degrees of freedom in regular and irregular waves, analyze hydrodynamic pressure distributions on ship hull and compute sea loads including shear forces, bending and torsion moments on any hull section.
Ship Structural Strength by means of global strength evaluation, generally means evaluation of the stress levels related to the hull beam idealization, considering the main global load effects due to both wave and still water conditions acting on the hull as longitudinal bending moment, both hogging and sagging, shear force and torque moment. The Longitudinal Strength combines the hull data and the loading conditions, in order to derive shear force and bending moment diagrams. An extreme wave profile is defined, with its crest at a specified point along the hull, in order to calculate for maximum hogging and sagging cases. When the loads are determined, the section data found by integrating under the hydrostatic calculations are used in order to balance the vessel, either in still water or on the wave profile specified. The resulting curve of buoyancy is added to the load curve in order to calculate the Shear Force. The shear force data are then
integrated to produce Bending Moment values. The bending moment data are used to create data for deflections. Data are calculated at all weight discontinuities. In addition, points may be requested at each station along the vessel. The resulting wave profile may be output as well as the strength data. The results are illustrated with plots of Shear Force, Bending Moment, Vertical Deflection, and Longitudinal Position. In this book we will examine the structural response to quasi-static loads. The hull girder is sized to resist the combination of self-weights and wave forces. We will focus on techniques for understanding ship global structural strength assessment. We will also review and expand, somewhat, on the mechanics of individual elements in local strength assessment.
Ship Economics investment analysis is a complicated activity which includes the preparation and the execution phase of investment projects within shipping companies. To ensure intended operational performance, the company must acquire a modern fleet as well as profitable contracts for its operations. The latter largely depends on the quality of managerial decisions. The investment activity of a shipping company involves deciding, on the one hand, when and how to acquire ships to augment the available tonnage and, on the other hand, when and how to sell the available capacity with maximum financial benefits. It is essential to carry out a careful analysis of alternative investments. These include purchase of new tonnage (newly built ships), purchase of tonnage previously operated by other shipping companies (second-hand tonnage), or upgrading of existing ships. In this book we examine investment projects from the point of view of the investor (shipping
company) and we present models to be used in investment analysis prior to project implementation.
A Computer Based Approach Using Excel Spreadsheets with VBA is the main feature of this book that distinguishes it from other books of this kind. The book includes a full-featured hydrostatics, stability and longitudinal strength program for the PC that performs all calculations that are usual needed by deck officers and other naval architectural related staff. Spreadsheets reinforces the book's presentation of key topics, with examples worked out for practical use. A powerful hydrostatic analysis software package is included that is useful for the chapters of the book dealing with ship hull geometry and hydrostatic stability.
Users of computer software must have a solid understanding of the principles of analysis and design to ensure that analysis results and design decisions are based on reliable foundations. I recommend that the hydrostatic analysis software be used only after mastering pertinent principles on which the software is based using careful study manual techniques.
The advantage of using the software after appropriate prior study is that many additional and more complex practice problems can be solved in the allocated time to give users more in-depth understand the behaviour of ships for a variety of hull geometries, hull shapes, loading patterns, and support conditions. They can pursue several alternative designs and work towards more optimum results.
Naval Architecture is an engineering discipline dealing with the design, construction and repair of marine vehicles. The Science of Naval Architecture is a multidisciplinary program designed to integrate the sciences with areas of traditional engineering such as research, design and analysis. This involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction, trials, operation and maintenance, launching and dry-docking are the main activities involved. Naval architects undertaking vital principles of naval architecture meet the growing requirements of marine world, making it a safer place with reliable quality.
Tracing back to the history of naval architecture, it shows naval architecture was never the scientific discipline as it is looked upon today. It followed the same procedure and vessel structure for years, without mentioning an idea for change or innovation. But as for now, things are different and marine world has become more complex and as a result, it requires more detail, research and focus to even sketch a design for a new vessel or watercraft. Naval architecture, now a scientific and engineering discipline exploits unique techniques and software along with intensive research and expert knowledge from different correlated fields to calculate and provide the ideal outcome.
In this book I use an up-to-date approach with the latest happenings in the field of naval architecture.
This book is based on my notes and collected material related to ship geometry, ship hydrostatics, ship stability, ship strength and ship economics during the last three decades. The book reflects the author's own experience in naval architecture & marine-/mechanical engineering and incorporates improvements based on contributions of many practitioners and research workers to my understanding of naval architecture, upon whose work I have drawn.
This book gathers together in one place a wealth of factual information concerned with ship geometry, hydrostatics, stability and strength. The information is presented in a logical and clear format comprising seven well-indexed parts, the first Introduction and Definitions, the second Applied Mathematics and Numerical Methods for Naval Architecture, the third Ship Geometry, Hydrostatics, Stability, Weight and Trim, the fourth Dynamics and Strength, the fifth Economics in Naval Architecture, the six Computer-Based Tools in Naval Architecture and introduction to the accompanying CD, and the seventh with References and Appendixes.
With each part the basic concepts behind are first considered, and then progressively developed, to show the modern methods utilized in today's Naval Architecture.
One aim of the book is to provide a physical understanding through simplified mathematical models. In this way one can develop analytical tools to evaluate results from computer simulations, and learn which parameters represent the major contributions and influences. A fair proficiency in the theory of ship geometry, hydrostatics, stability, motion and sea loads and strength is assumed. The book is written to meet the needs for practical tools to use the information in 'real life' situations.
The book will also provide to be extremely useful to Maritime Studies degree, and serves as a quick and handy reference for seafarers and students alike and an important resource for naval architecture students, shipboard officers and shore-based staff, including dry-dock personnel, ship-designers, ship surveyors, port authorities, marine consultants and superintendents. The text is also written for engineers and scientists interested in problems related to the design and operation of ships.
It is also a relevant reference work for on board usage and as a guide for Deck Officers and Naval Architect who need practical tools to use the information in 'real life' situations. This book will become a desk companion to many ships officers and naval architects and will be a must-have for any ships library, as well as on the book shelves.