OCEAN STATION VESSELS 



Official U. S. Coast Guard Photographs 



10-mile square but still on the grid, the latitude and longitude 

 designators of whatever square the ship is in are transmitted as the 

 last 2 letters of the signal. The latitude designator is always given 

 first. The center of each grid square should be considered the 

 location of the station vessel for all computations, thus giving a 

 maximum error of 7.1 miles and an average probable error of 2.5 

 miles. 



EXAMPLE: Assuming we are considering station "ALFA" with 

 the actual position of the station vessel at the point marked "X" on 

 the grid in Figfure 1, her signal would be "YAIN". It is also evident 

 that the station vessel bears 63° true 45 miles from its assigned 

 position. 



The emission of the radiobeacon has a high degree of vertical 

 polarization which may enable a surface vessel to obtain a good 

 bearing at distances in excess of 200 miles. If the regular beacon 

 equipment breaks down, the same service as described above will be 

 given, except that the ship's communication transmitter will give 

 an interrupted tone-modulated signal in place of the continuous 

 carrier wave. In this case, the identifying signal will be followed 

 by a 20-second dash in order to provide service for automatic direc- 

 tion finders. If a station vessel is off the grid completely, as when 

 on a distress mission, no beacon service will be furnished, except 

 when specifically requested for homing purposes. In this event, the 

 international radio call of the station will be used as the identifying 

 signal. 



CAUTION TO ALL SHIPMASTERS - AVOIDANCE OF 

 COLLISION WITH OCEAN STATION VESSELS-Instances have 

 been reported of ships "homing" on beacon transmissions of these 

 vessels on station. This practice creates a grave danger of collision. 

 Vessels occupying ocean stations may be drifting with engines on 



standby. Standby, in this instance, means that the vessel is not able 

 to maneuver as propulsion power is not immediately available to the 

 bridge. While ocean station vessels are drifting on station they 

 use the lights and shapes prescribed by Rule 4(a), International 

 Rules, and the fog signals prescribed by Rule 15(c) (v) , International 



'The collective sign for any or all United States ocean station vessels in the At- 

 lantic is NMMZ. 



The collective call sign for any or all United States ocean station vessels in 

 the Pacific is NDLZ. 



'Operates for 5-minute periods beginning at 5, 20, 35, and 50 minutes past each 

 hour and on request. 



^Operates for 5-minute periods beginning at 5, 20, 35, and 50 minutes past each 

 hour but may be interrupted 1100-1200 and 2300-2400 GMT due to radiosonde obser- 

 vations. 



On request. 



Figure 2 Pertinent data regarding ocean station vessels. 



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