station is carried out by the senior scientist 

 with the assistance of the other oceanographers. 

 The decision as to what observations will be 

 taken will depend upon local conditions as well 

 as the requirements of the survey. 



Prior to arriving on station, the instruments 

 and equipment to be used are put in readiness. 

 When the navigator has determined that the 

 ship is at the desired position, the ship is 

 maneuvered in such a position that the side on 

 which the oceanographic winch is located is 

 facing into the wind. The ship's engines are 

 then stopped. 



Outboard from the oceanographic winch is 

 the platform, similar to a leadsman's chains, 

 with an A-frame over it. From the A-frame is 

 suspended a special block called a meter wheel. 

 This meter wheel has a stainless steel sheave, 

 of an exactly measured circumference, which is 

 connected to a meter box. The oceanographic 

 wire is passed over this meter wheel and the 

 amount of wire that is let over the side is indi- 

 cated by the meter box dials. A lead weight 

 of about 100 pounds is attached to the end of 

 the wire. This is lowered over the side, out- 

 board of the platform, after the ship is dead in 

 the water. A series of water sampling bottles 

 with attached thermometers, one type used 

 by the U. S. Navy is called a Nansen bottle, 

 are attached to the wire at various depths. 

 After these samples, with their temperatures, 

 are taken, a series of plankton tows may 

 be made. These might be followed with 

 a lowering of the underwater camera or a 

 coring device to the bottom. 



The time involved in taking a series of 

 observations as described above in water about 

 4,000 meters deep would be approximately 7 

 hours. If a large coring device, such as the 

 half-ton Ewing piston corer, were lowered by 

 the anchoring winch to this depth, it would 

 take some 5 hours to lower and raise it for a 

 single core. 



Many observations can be taken simultan- 

 eously. Thus, bathythermograph lowerings, 

 surface plankton tows, subsurface visibility 

 measurements, wave measurements with the 

 electric wave staff, and the associated meteor- 

 ological observations, can be taken while other 

 lowerings are in progress without adding to 

 the time on station. 



The efficiency with which the observations 

 and measurements are obtained during the time 

 the ship is occupying the oceanographic station 

 naturally depends upon the number of person- 

 nel available to assist and the degree of training 

 they have had. On the U. S. Navy survey 

 ships, there may be anywhere from 3 to 12 



men assisting the oceanographers, depending 

 upon the requirements for a particular station. 

 It takes about 8 men to rig and get the Ewing 

 piston corer over the side. Nansen bottle 

 casts take about 3 men; a winch operator, 

 a platform man, and a bottle passer. It takes 

 about 4 men to rig and operate the electric 

 wave staff. 



After the last piece of equipment is back 

 aboard, the ship gets underway and heads 

 for the next station, which may be a few miles 

 or possibly a hundred miles away. While 

 steaming to the next station, current measure- 

 ments using the Geomagnetic Electrokineto- 

 graph (GEK) may be taken. The equipment 

 and instruments just used are cleaned, the 

 samples obtained are stored, and preparations 

 for the requirements of the next station are 

 made. In the drafting room or scientific office 

 and in the laboratories, work is started on 

 computing and analyzing the data recently 

 obtained. The temperature and depth calcu- 

 lations are carried out, chemical titrations are 

 run, and the data are checked. This work is 

 more laborious and time consuming than that 

 of occupying the station itself. 



1-14 DEEP-SEA ANCHORING.— Obser- 

 vations taken during a deep-sea anchor station 

 generally are similar to those described above; 

 however, the problems of high wire angles due 

 to the drifting of the ship are not present 

 although wire angles due to current may be 

 troublesome at times. In addition, current 

 measurements with both mechanical and elec- 

 trical current meters are taken. The observa- 

 tions taken on anchor stations usually are 

 repeated at definite time intervals while at 

 anchor. Current observations are carried out 

 through one or more tidal cycles. 



Deep-sea anchoring involves techniques 

 slightly different from ordinary shallow-water 

 anchoring. It generally is a fair-weather 

 operation. Of necessity the anchoring equip- 

 ment is light. Anchors used by U. S. Navy 

 survey ships are 500-pound Danforth type. 

 The anchor is attached to the half-inch wire. 

 The scope-to-depth ratio normally used for 

 deep-sea anchoring is less than that required 

 by shallow anchoring. In shallow anchoring, 

 ratios of 5 to 1 or greater are used frequently, 

 while in deep-sea anchoring, ratios greater than 

 3 to 1 are rare. The reasons for this are the 

 great depths involved compared to the length 

 of available cable ; the amount of scope lying 

 on the bottom for deep-sea anchoring is prob- 

 able far greater for a small ratio than that on a 

 shallow bottom with a large ratio; and finally, 

 the drag, or resistance, of the cable in the water 



H. O. 607 



