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1584. International Code Flags 



A complete set of International Code flags shall be carried for navigational purposes, 

 being displayed as the occasions require. 



A card illustrating the various flags shall be kept in the pilothouse in a convenient 

 location. 



Ships and auxiliary vessels engaged in hydrographic surveying underway in the 

 daytime should display suitable International Code signals in areas where there may be 

 considerable foreign steamer traffic. The appropriate International Code signals are : 



"HD," signifying "I am engaged in submarine work, you should keep clear of me." 

 "HF," signifying "I (we) have a sweep out, you should keep clear of it." 

 "ONA," signifying the same as "HD." 



In addition to the above signals, the code flags most frequently used by ships of 

 the Coast and Geodetic Survey are the red flag to indicate that explosives or highly 

 inflammable fuels are being loaded, and those composing the groups used in recalling 

 launch and shore parties. 



1585. Signals for Use During Hydrographic Surveying 



The special signals prescribed for daytime use to indicate that a vessel underway 

 is engaged in hydrographic surveying are three shapes, not less than 2 feet in diameter, 

 carried in a vertical line, not less than 6 feet apart, where they can best be seen ; the 

 highest and lowest shall be globular in shape and green in color, and the middle one 

 diamond in shape and white in color. 



Ships and auxiliary vessels of the Coast and Geodetic Survey shall carry the 

 above prescribed marks at all times while actually engaged in hydrographic surveying 

 underway, includmg wire-drag operations. Launches and other boats shall carry the 

 prescribed marks when necessary. 



By night a survey vessel of the Coast and Geodetic Survey, engaged in hydro- 

 graphic surveying underway, shall carry the regular lights prescribed by THE RULES 

 OF THE ROAD. 



A vessel of the Coast and Geodetic Survey, engaged in survey operations at anchor 

 in a fairway, shall display from the mast during the daytime two black balls in a vertical 

 line and 6 feet apart. At night two red lights shall be displayed in the same manner. 

 In the case of a small vessel the distance between the balls and between the lights 

 may be reduced to 3 feet if necessary. A flare-up light shall be kept at hand and shown 

 if necessary to attract attention in addition to the two red lights prescribed. 



It must be emphasized that the display of the prescribed shapes or the flag code 

 signals serves only to indicate the nature of the operations and in no way gives the 

 survey vessel the right-of-way over other vessels nor relieves it from a strict observance 

 of the rules for the prevention of collisions of vessels. 



When it is apparent that an approaching vessel does not heed signals displayed 

 by the survey vessel, the ''danger signal" (not less than four short and rapid blasts 

 of the whistle) should be sounded by the survey vessel. 



159. Coast Pilot Reports 



All hydrographic parties shall collect coast pilot information and furnish at the 

 end of each season a special report on this subject for use in the revision of the Coast 

 Pilot of the area. This report should include mformation obtained while en route to 

 and from the project area as well as that gathered on the working ground. It should 

 be a compilation made from the notes and memoranda kept by each hydrographic 



