Saturday, October 17, 2009

Ship’s Displacement Calculation using Simpson’s Rule

Before we begin to calculate displacement of a ship, please watch the following video to understand the basic theory of how Simpson's rule is applied in calculating areas of curves.

Displacement of a ship is the volume of sea or fresh water displaced by the ship when floating. The specific weight of the seawater is heavier than freshwater. When a ship sails from the sea into a river, her draft increases. The volume of the displaced water is the same as the volume of the immersed hull of the ship. To calculate the volume of the immersed hull, first, we must calculate the several equidistantly spaced waterplane areas from the keel to the designed load waterline.

Please, read my previous post on Boat's Waterplane Area Calculation Using Simpson's Rule which I uploaded on this Naval Architecture blog yesterday.
The method for calculating the displacement volume is the same as the one used in calculating waterplane area. All naval architects are familiar with Simpson's rule. 
Now, all the design and calculation of ship forms can be executed using such computer software as Delftship, and Maxsurf or Orca 3D (a plugin of Rhinoceros 3D modelling software for naval architecture). But all students of naval architects must perform semi-manual calculation using Microsoft Excel or other spreadsheet software to help them understand the whole philosophy of hydrostatic calculations of a ship.  

Please, read the classic Basic Ship Theory to know more about Simpson's Rules and their application in ship design. by Charles Roring


Yongda said...

Can I kindly check with you, what if the draft are of different values at different stations? What would be the CI value? Also I have read your article on finding of water plane area. Why do you use 2/3*F(A)*2 and not F(A)*2.Thanx

Charles Roring said...

The stations in the half breadth ordinates are equidistantly spaced for 2 meters as CI or Common Interval. Because the calculation is area is calculated for both sides of the ship or boat then The area of waterplane = 2/3 x Common Interval x Area Function

Unknown said...

interesting blog. It would be great if you can provide more details about it. Thanks you.

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