The Engineering Diary

Types of Ships Cargo ships are classified into various types on the basis of purpose, size, type of cargo etc. The economic factor is of prime importance in designing a merchant ship. Every owner wants maximum return on their investment which means a ships construction not only depends on the current economic necessities but the factor of future adaptability also plays a part. From the preliminary design of a vessel due for construction, the following information can be obtained: 1.      Dimensions 2.      Displacement 3.      Stability 4.      Propulsive characteristics and hull form 5.      Preliminary general arrangement 6.      Principal structural details A layout of the various ship types and their subdivisions will be listed out, covering a wide range of all vessels in operation.  The type of ship plays an important role in deciding the above mentioned parameters. Types of Ships Ships are mainly classified into the following types: 1. Container Ships 2. Bulk Carrier 3. Tanker Sh

Gearing and tail shafts Vessels with low speed engines typically use direct drive from the crankshaft to the tail shaft with its propeller. Smaller domestic commercial vessels typically operate with high speed engines where direct drive shafts would revolve too fast to drag water across their propellers without efficiency losses due to cavitation (bubbling in the water flow). Consequently a gearbox is used to provide reduced speed of the shaft, reverse propulsion and through a clutch mechanism, disengaged propulsion. Gears and clutch mechanisms Principles of marine gear boxes Gearing is used in drive trains (sets of intermeshed gear wheels) to alter direction, position or speed/mechanical advantage of propulsion and auxiliary equipment such as winches, pumps and steering. The gear and shaft driven directly by the motor can be called the input and the final gear and shaft it drives can be called the output. Drive train A shown below illustrates reduction and reversal of the output, driv