CHAPTER XXI 



REMARKS ON TRI ANGULATION BY MEANS 

 OF FLOATING MOORED BEACONS 



AND 



THE GENERAL PROCEDURE FOR VESSELS WHEN 

 CO-OPERATING OUT OF SIGHT OF LAND 



By REAR-ADMIRAL FREDERICK C. LEARMONTH, CB., C.B.E. 



PREFATORY REMARKS. 



Hydrographic surveys which depend almost entu'ely upon 

 the use of floating beacons call for extra attention and vigilance 

 on the part of those conducting them. 



With the increasing size of vessels, whose load draught has 

 already attained to beyond 36 feet, much of the future work of 

 marine surveys will be necessarily occupied in a close re- 

 examination of frequented areas, when any aids to accomphsh- 

 ing this end are gladly welcomed by the surveyor in the 

 endeavour to keep in hne with modern requirements. 



There is nothing that can be described as new in the remarks 

 that are here set forth, and no attemj^t has been made to lay 

 down any hard-and-fast rules. 



It is recognised that the circumstances of any two surveys 

 are never likely to be the same, and that much must be left 

 to the Judgment of the officer in charge of a survey to meet 

 the particular circumstances that may arise. 



These remarks have been drawn up and are largely based upon 

 the experiences of past years under varying conditions, in- 

 cluding that gained in the North Sea Survey, which has been 

 in progress since 191 1, and carried out entii-ely by means of 

 floating beacons by one directing vessel, together with one or 

 more vessels co-operating. 



As far as it is desirable, some attempt is here made to stan- 

 dardise methods and co-ordinate results, in order that the 



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