PROPULSION OF VESSELS 



239 



Determining Fineness of Vessel. To determine whether 

 a vessel is fair or fine, its displacement, in cubic feet, is usually 

 compared with the volume of a rectangular box having a length 

 equal to the length of the vessel on the water-line, a width 

 equal to the beam, and a depth equal to the mean draft of the 

 vessel diminished by the depth of the keel. If the displacement 

 is .55 of the volume of the box, or less, the vessel is fine; if 

 above .55 and less than .70, fair. The quotient obtained by 

 dividing the displacement by the contents of the imaginary 

 box is called the coefficient of fineness. 



VALUES OF * IN ADMIRALTY RULE 



Selecting Constant in Admiralty Rule. The selection of 

 a proper value of k calls for the exercise of considerable judg- 

 ment, based on personal knowledge of the actual performance 

 of similar vessels. Generally speaking, the value of k is influ- 

 enced by the length, speed, and shape of the vessel. The 

 value of k should be greater with an increased length of the 

 vessel in proportion to the width, and also with a finer under- 

 water body; conversely, its value should be less as the ratio of 

 length to width becomes smaller, and as the form becomes 



