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. Additionally, he must estimate the shaft horsepower required for the specified speed this determines the weight of machinery. He must also select a moment balance because centres of gravity in both longitudinal and vertical directions must provide satisfactory trim and stability. The draft-which is governed by freeboard rules-enables the depth to be determined to a first approximation.Īfter selecting tentative values of length, breadth, depth, draft, and displacement, the designer must achieve a weight balance. The fineness of the hull must be appropriate to the speed. The designer must choose dimensions such that the displacement of the vessel is equal to the sum of the deadweight and the lightweight tonnages. 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 requirements high-density cargoes, such as machinery, require little hold capacity, while the reverse is true for low-density cargoes, such as grain.ĭeadweight is defined as weight of cargo plus fuel and consumable stores, and lightweight as the weight of the hull, including machinery and equipment. The naval architectĪ naval architect asked to design a ship may receive 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. What is the area “near, toward, or in the stern of a ship”? Which sailing maneuver involves quickly changing a ship’s direction? Test your knowledge.

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