NOTES ON DOCKS AND DOCK CONSTRUCTION. 



as littl.' xwoll inside as possible. This cannot by any practical 

 r instruction be entirely avoided, but means should be taken 

 wit bin the harbour to reduce the recoil of the waves to a 

 minimum. 



Site for Imperial Docks. As regards the selection of a site for 

 an imperial establishment, the following conditions will require 

 special attention. A depth of water sufficient to allow of the 

 sills of docks and basins being placed so low as to admit, at 

 low-water spring tides, the largest class of naval ships at what 

 may be considered damage-draught. Spacious and well-sheltered 

 anchorage of an area sufficient to accommodate a large number 

 of vessels. Natural protection from an enemy's tire. Central 

 position on the coast line, with ready and convenient means of 

 communication with manufacturing districts particularly, and 

 with all parts of the country generally. Close proximity to a 

 well-protected roadstead, or harbour. 



Prevailing Winds. It will be necessary to give some con- 

 siderable attention to the direction and force of the prevailing 

 wind, as regards the position of an entrance particularly, and the 

 site of enclosed basins and docks generally. In the first case, 

 currents may be generated which it would be desirable, if 

 possible, to avoid. Secondly, a site may possess every advan- 

 tage in all other respects, yet it may be, if fully exposed to high 

 prevailing winds, unsatisfactory, inasmuch as the wind acting 

 on the high masts and rigging of vessels alongside the wharves 

 may cause them to work and chafe, and thus give rise to con- 

 siderable damage. 



General Plan of Basins. The general plan and width of dock 

 to afford the maximum accommodation, combined with the 

 greatest facilities for manoeuvring ships, will depend in a great 

 measure upon the class of ships and the nature of the trade to be 

 accommodated, modified in the majority of cases by local con- 

 ditions and peculiarities of the available site. 



Width of Basins. The most suitable width of basins is a 

 point on which, as on many others appertaining to dock con- 

 struction, some difference of opinion exists; some experts con- 

 tending that, in view of the increasing length of ocean-going 

 steamers, docks for their accommodation should not be less than 

 GOO feet wide in some particular part where* a long ship could be 

 turned, whilst others contend that tin-re should be no difficulty 

 in working a narrower dock, inasmuch as, with proper appliances, 



