文档介绍：精选优质文档-----倾情为你奉上
精选优质文档-----倾情为你奉上
专心---专注---专业
专心---专注---专业
精选优质文档-----倾情为你奉上
专心---专注---专业
船舶与海洋ve his instructions in a form ranging from such simple requirements as “an oil tanker to carry 100 000 tons deadweight at 15 knots” to a fully detailed specification of precisely planned requirements. He is usually required to prepare a design for a vessel that must carry a certain weight of cargo (or number of passengers ) at a specified speed with particular reference to trade requirement; high-density cargoes, such as machinery, require little hold capacity, while the reverse is true for low-density cargoes, such as grain.
Deadweight is defined as weight of cargo plus fuel and consumable stores, and lightweight as the weight of the hull, including machinery and equipment. The designer must choose dimensions such that the displacement of the vessel is equal to the sum of the dead weight and the lightweight tonnages. The fineness of the hull must be appropriate to the speed. The draft------which is governed by freeboard rules------enables the depth to be determined to a first approximation.
After selecting tentative values of length, breadth, depth, draft, and displacement, the designer must achieve a weight balance. He must also select a moment balance because centres of gravity in both longitudinal and vertical directions must provide satisfactory trim and stability. Additionally, he must estimate the shaft horsepower required for the specified speed; this determines the weight of machinery. The strength of the hull must be adequate for the service intended, detailed scantlings (frame dimensions and plate thicknesses ) can be obtained from the rules of the classification society. These scantings determine the requisite weight of hull steel.
The vessel should possess satisfactory steering characteristics, freedom from troublesome vibration, and should comply with the many varied requirements of international regulations. Possessing an attracti