OCEANOGRAPHY OF THE GRAND BANKS REGION AND 

 LABRADOR SEA, 1948 



BY FLOYD M. SOULE, H. H. CARTER, AND L. A. CHENEY^ 



Since the International Ice Patrol was discontinued in December 1941, 

 because of the then existing war conditions and disruption to normal 

 maritime commerce and practices in the North Atlantic, the availability 

 of ships, equipment and personnel did not combine to permit the resump- 

 tion of an oceanographic program until the season of 1948. For this 

 season a 180-foot tender-class cutter, the USCGC Evergreen, was desig- 

 nated as the oceanographic vessel of the International Ice Patrol. A 

 small laboratory was fitted out on the main deck and oceanographic 

 winches, platforms, gallows frames, a rack for Nansen water bottles, 

 and a bathythermograph winch were installed on the fantail. The 

 laboratory was located nearly midway in a fore-and-aft direction, where 

 the vibration was a minimum. Vibration on the Evergreen was excessive, 

 partly from the engines, but principally associated with the propeller. 

 As the vibration was so extreme, the location of the laboratory, in the 

 area of least vibration, was the best compromise, in spite of the dis- 

 advantages of noise and excessively high temperatures arising from the 

 laboratory's proximity to the engine room spaces and its location directly 

 above the heating boiler and evaporator. Aside from the more rapid 

 deterioration of instruments and equipment the unfavorable conditions 

 in the laboratory probably had a direct effect in lowering the accuracy 

 of measurements and computations. As the vibration on the fantail 

 was the worst of all parts of the ship during the runs between stations, 

 those thermometer readings made after leaving a station probably contain 

 observational errors v/hich are larger than they should be. 



In spite of the serious nature of these shortcomings the really big 

 question as to the suitability of the Evergreen for oceanographic work was 

 whether, when hove to, in wind velocities ordinaril}^ experienced, the wind 

 drift of the vessel would produce wire angles too great for successful 

 operation of the overl^oard gear. As a result of the 1948 experience 

 gained with the Evergreen, it can be stated that with the ship hove to and 

 dead in the water oceanographic stations can be worked successfully 

 with wind velocities up to about 20 or 22 miles per hour at which the wire 

 angle reaches the upper usable limit of about 45°. With wind velocities 

 between 30 and 35 miles per hour the wire angle can be kept below 45° 

 and reasonably constant by steaming into the wind at slow speed and 

 keeping the wind just off the bow on the side from which the gear has 

 been shot. With wind velocities below about 30 miles per hour difficulties 

 are experienced in maintaining steerage way with speeds slow enough not 

 to produce excessive wire angles fi'om towing the gear. With winds 

 above about 35 miles per hour difficulty is experienced in holding the 

 ship's heading without the use of excessive speed to bring her back 



' Contribution Xo. 467 of the Woods Hole Oceanographic Institution. 



67 



