Lection1船舶原理英文版

Lection 1 (23.11.2011, Wednesday)

Introduction. The ship theory concept. Ship co-ordinate system. Vessel requirements. Classification societies. Ship body plan (lines plan). Ship principal dimensions.

Introduction

A crude representation of the process of creating a ship is outlined in the figure:

For determination of ship hull form geometry and position of the ship with respect to the surface of the water, the left-hand co-ordinate system, rigidly linked with the ship, is used.

An origin of this co-ordinate system, the point o, is placed upon keel line in the point of intersection of the base plane, the plane of mean transverse section of the ship body and the plane of its longitudinal symmetry.

The axis ox is pointed forward, being by line of intersection of the centre plane and the base plane. The axis oy is line of intersection of the midstation plane and the base plane; its positive direction is the direction to the right side of the ship. The axis oz is line of intersection of the midstation plane and the centre plane, the positive direction of this axis pointing upward.

Thus, the plane xoy is the base plane, plane xoz is the centre plane, and plane yoz is the midstation plane.

Co-ordinate system

The ship theory concept

The ship theory is the science of its seakeeping (seaworthiness): buoyancy, stability, insubmersibility, propulsion, maneuverability, motion (rolling).

Buoyancy – the vessel's ability to swim in a certain position relative to the surface of the water, carrying all designed according to his service loads.

The stability of the ship – the ability to swim in a live situation and return it as soon as the will to act by external forces, had rejected a vessel from the situation.

Insubmersibility –the vessel's ability to maintain buoyancy and stability when sinking one or group of compartments.

Propulsion – the vessel's ability to develop a certain speed with the power of main engines and corresponding pumped propulsion systems. The ship's engine is a special device (e.g., propeller), which transforms the energy of the main engine driving the ship.

Control –the vessel's ability to change direction when transferring the rudder and move in a straight line with the position of the rudder on the centerline.

Rolling – fluctuations of a vessel concerning balance position.

Seaworthy qualities, at which studying the vessel is considered as a motionless body (buoyancy, stability, insubmersibility), unite section "Statics ship".

Seaworthy qualities, at which studying the vessel is considered as a moving body (propulsion, control, rolling), unite section "Dynamics ship".

Vessel requirements

Vessel –floating structure, capable of performing certain tasks: transportation of people and goods, towing of other vessels, etc., therefore, each vessel must comply with its intended purpose and have a range of qualities, among which are:

– the overarching sufficient navigation safety in terms of seaworthiness, and taking into account the effects of other factors (e.g. fire safety);

– optimum speed in the selected direction, taking into account the purpose of the vessel;

–sufficient strength, durability and reliability of the hull, mechanisms, equipment, etc. with a minimum of their weight;

– minimum freight ton or per passenger for a certain distance – for cargo and passenger ships; minimum cost of production of one tonne of fish –for fishing vessels, etc.;

– the largest payload capacity in data sizes and for cargo vessels; maximum passenger capacity for passenger vessels, etc.;

–mechanization and automation of management of ship power plants, support mechanisms and the ship as a whole;

–the availability of high-performance devices that provide the ability to perform basic tasks ship ship means, for example, cargo handling operations;

– good working conditions and welfare team;

–the lowest cost of construction of vessel.