CHAPTER IX. 



Floating Docks Classification Durability Strains Applicability Conditions 

 affecting design Stability Cartagena Dock Off-shore floating Dock 

 Depositing Dock Hydraulic lifting Dock. 



A FLOATING dock is any structure capable of lifting a vessel 

 out of the water, and supporting it by virtue of its own buoyancy 

 stability. As a rule, for a given displacement, the length being 

 constant, the stability of a floating body varies in direct 

 proportion to its breadth. 1 Therefore, the form usually adopted 

 for floating docks is the rectangular, with a breadth large in 

 proportion to the depth of immersion, which varies from J to -j\) 

 of the breadth. But as the stability is materially influenced by 

 the height of the centre of gravity above the line of flotation, 

 other sections approaching a semicircular form may, by lower- 

 ing the centre of gravity, have a stability equivalent to the 

 rectangular form. 



This form requires the ends to be closed, either by gates 

 or caissons, after the vessel has entered, as the keel of the 

 vessel would be considerably below the line of flotation of 

 the dock. 



In a rectangular dock, the same stability is obtained without 

 closing the ends, and usually there is less water to discharge. 



With a circular form of bottom, the volume of water between 

 the outside of the ship and the inside of the dock has to 

 be disposed of, while, with a rectangular form, only the quantity 

 of water representing the weight of the ship and dock has 

 to be cleared. In one case, the quantity of water to be pumped 

 will vary as the weight of the ship ; but, in the other case, the 

 smaller the vessel the greater will be the quantity of water to 

 be discharged. 2 



Classification. Any structures with sides of an equal ami 

 uniform height throughout, and the ends closed by gates or 

 M.P.IC.E., vol. xxxi. p. 299. Ibid. 



