Sunday 29 January 2017

Topic-2 COEFFICIENT OF FORM

    Block Coefficient (CB)

Block coefficient of fineness is the ratio of the volume of displacement () of the molded form up to any waterline to the volume of a circumscribing solid with length, breadth, and depth equal to the length, breadth and draught of that waterline. 
The Block Coefficient (CB) is given by,
CB = /L×B×T

       Midship section area coefficient (CM)

The fullness of the midship section is expressed by the midship section area coefficient. It is the ratio of the midship section area to the circumscribing rectangle, the width of which is equal to the molded beam at the load waterline and the depth of which is equal to the molded draught at that waterline.
The midship section area coefficient is given by,
CM = AM / B×T

       Water plane area coefficient (CW)

The Water plane area coefficient influences the resistance and stability considerably. It is geometrically related to shape of cross-sections. It is the ratio of Water plane area to the circumscribing rectangle, the length of which is equal to the length of the LWL and width of which is equal to the breadth at that waterline. The value of CW is largely a function of CB and sectional shape.
The Water plane area coefficient is given by,
CW = AW / L×B

      Longitudinal Prismatic coefficient (CPL)

The longitudinal prismatic coefficient is the ratio of molded volume of the ship up to the designed waterline to the volume of prism having length equal to the waterline length and cross-sectional area equal to the midship section area. It is the ratio of CB to CM.
The longitudinal prismatic coefficient is given by, 
CPL = CB / CM

        Vertical Prismatic coefficient (CPV)

The vertical prismatic coefficient is the ratio of molded volume of ship up to the designed load waterline to volume obtained by the product of Water plane area with the draught. It is the ratio of CB to CW.
The vertical prismatic coefficient is given by,

                                                                   CPV = CB / CW

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