Technology & Engineering
Boat Hull
A boat hull is the main body of a boat or ship that provides buoyancy and stability in water. It is designed to displace water and support the weight of the vessel and its cargo. The shape and size of the hull can affect the boat's speed, maneuverability, and seaworthiness.
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4 Key excerpts on "Boat Hull"
eBook - PDFShip Resistance and Propulsion
Practical Estimation of Ship Propulsive Power
- Anthony F. Molland, Stephen R. Turnock, Dominic A. Hudson(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
14 Hull Form Design 14.1 General 14.1.1 Introduction The hydrodynamic behaviour of the hull over the total speed range may be separated into three broad categories as displacement, semi-displacement and planing. The approximate speed range of each of these categories is shown in Figure 14.1. Con- sidering the hydrodynamic behaviour of each, the displacement craft is supported entirely by buoyant forces, the semi-displacement craft is supported by a mixture of buoyant and dynamic lift forces whilst, when planing, the hull is supported entirely by dynamic lift. The basic development of the hull form will be different for each of these categories. This chapter concentrates on a discussion of displacement craft, with some comments on semi-displacement craft. Further comments and discussion of semi- displacement and planing craft are given in Chapters 3 and 10. 14.1.2 Background The underwater hull form is designed such that it displaces a prescribed volume of water , and its principal dimensions are chosen such that ∇ = L × B × T × C B , (14.1) where is the volume of displacement (m 3 ), L, B and T are the ship length, breadth and draught (m) and C B is the block coefficient. In theory, with no limits on the dimensions, there are an infinite number of com- binations of L, B, T and C B that would satisfy Equation (14.1). In practice, there are many objectives and constraints which limit the range of choice of the dimen- sions. These include physical limits on length due to harbours, docks and docking, on breadth due to harbour and canal restrictions and on draught due to opera- tional water depth. Combinations of the dimensions are constrained by operational requirements and efficiency.
eBook - PDFShip Resistance and Propulsion
Practical Estimation of Propulsive Power
- Anthony F. Molland, Stephen R. Turnock, Dominic A. Hudson(Authors)
- 2011(Publication Date)
- Cambridge University Press(Publisher)
14 Hull Form Design 14.1 General 14.1.1 Introduction The hydrodynamic behaviour of the hull over the total speed range may be separ- ated into three broad categories as displacement, semi-displacement and planing. The approximate speed range of each of these categories is shown in Figure 14.1. Considering the hydrodynamic behaviour of each, the displacement craft is suppor- ted entirely by buoyant forces, the semi-displacement craft is supported by a mix- ture of buoyant and dynamic lift forces whilst, when planing, the hull is supported entirely by dynamic lift. The basic development of the hull form will be different for each of these categories. This chapter concentrates on a discussion of displacement craft, with some comments on semi-displacement craft. Further comments and discussion of semi- displacement and planing craft are given in Chapters 3 and 10. 14.1.2 Background The underwater hull form is designed such that it displaces a prescribed volume of water ∇, and its principal dimensions are chosen such that ∇ = L × B × T × C B , (14.1) where ∇ is the volume of displacement (m 3 ), L, B and T are the ship length, breadth and draught (m) and C B is the block coefficient. In theory, with no limits on the dimensions, there are an infinite number of com- binations of L, B, T and C B that would satisfy Equation (14.1). In practice, there are many objectives and constraints which limit the range of choice of the dimen- sions. These include physical limits on length due to harbours, docks and docking, on breadth due to harbour and canal restrictions and on draught due to opera- tional water depth. Combinations of the dimensions are constrained by operational requirements and efficiency. These include combinations to achieve low calm water resistance and powering, hence fuel consumption, combinations to behave well in a seaway and the ability to maintain speed with no slamming, breadth to achieve 313
eBook - ePub- George J. Bruce, Keith W. Hutchinson, George J Bruce, David J Eyres(Authors)
- 2012(Publication Date)
- Butterworth-Heinemann(Publisher)
Part 5
Ship Structure
Introduction
Introduction
Ships are the largest, mobile man-made structures in the world. The largest ships are comparable with major buildings, but have additionally to withstand enormous forces from wind and waves. Their structural arrangements are therefore of great importance. Because in most cases ships have to earn by carrying cargo, their structure not only has to be strong, it must also be as light as possible.The structure of a ship is based on flat and curved steel plate panels, with primary and secondary stiffening. The complete hull structure has to fulfill several important requirements. These include:• Maintaining watertight integrity • Separating internal spaces, for example cargo, fuel oil, ballast water • Resisting forces on the ship, in particular from waves.The structure also has to conform to the hull shape dictated by hydrodynamics, i.e. the performance in terms of speed and seakeeping specified by the hull designer.Both the forces on the ship and the capability of the structure have some uncertainty, which must be allowed for in the design. The structure may suffer from changes in material properties over the life of the ship. Some causes of structural failure are hard to predict, for example fatigue and corrosion. The quality of workmanship can also vary considerably.Basic structural arrangements
The structure of a ship is based primarily on panels, both flat and curved. These are the building blocks of the structure and also provide a convenient breakdown of the structure into units during ship construction (see Chapter 14 ).The basic components of the panels are steel plates and steel profiles. The plates form the panels and the profiles are used to provide stiffening to prevent the plates deforming when subjected to forces.
eBook - PDF- Adrian Biran(Author)
- 2003(Publication Date)
- Butterworth-Heinemann(Publisher)
The terminology is specific to this branch of Engineering and is based on a long maritime tradition. The terms and symbols introduced in the book comply with recent international and corresponding national standards. So do the definitions of the main dimensions of a ship. Familiarity with the terminology and the cor-responding symbols enables good communication between specialists all over 20 Ship Hydrostatics and Stability the world and correct understanding and application of international conventions and regulations. In general, the hull surface defies a simple mathematical definition. Therefore, the usual way of defining this surface is by cutting it with sets of planes parallel to the planes of coordinates. Let the x -axis run along the ship, the y -axis be transversal, and the z -axis, vertical. The sections of constant x are called sta-tions , those of constant z , waterlines, and the contours of constant y , buttocks . The three sets must be coordinated and the curves be fair, a concept related to simplicity, curvature and beauty. Sections, waterlines and buttocks are represented together in the lines plan . Line plans are drawn at a reducing scale; therefore, an accurate fairing process cannot be carried out on the drawing board. In the past it was usual to redraw the lines on the moulding loft, at the 1:1 scale. In the second half of the twenti-eth century the introduction of digital computers and the progress of software, especially computer graphics, made possible new methods that will be briefly discussed in Chapter 13. In early ship design it is necessary to choose an appropriate hull form and estimate its hydrodynamic properties. These tasks are facilitated by character-izing and classifying the ship forms by means of non-dimensional coefficients of form and ratios of dimensions.
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