Figure 160. Diagram of the surface currents in the Arctic Basin. 



invariably moved almost parallel to itself. In other words, the ship did not rotate, although actu- 

 ally it should inevitably have turned about if the effect of the wind had been felt only on it (the ship 

 itself) or on a limited area directly adjacent to the vessel. Departures from this rule were ob- 

 served only in cases of strong local hummocking, but these were of a temporary nature and at the 

 conclusion of the hummocking the ship usually returned to its former position. Such a steady be- 

 havior of the ship may be explained by the compactness of the ice in the drift region. 



This is demonstrated best by the fact that up to May of 1939 the true course of the Sedou var- 

 ied almost exactly as much as its longitude varied. Only on 6 May 1939 when the westerly move- 

 ment was intensified, was there noted a counter-clockwise turn of the ship amounting to 12°. This 

 unexpected turn of the ice evidently occurred in connection with the formation of a gigantic water 

 opening (2000 m wide, length beyond limits of visibility) which appeared on 9 April. In the ice sur- 

 rounding the Sedov there apparently occurred a certain amount of thinning in connection with the 

 ship's approach to the powerful East Greenland current. In any case, this phenomenon was intensi- 

 fied as the ship approached the straits between Spitzbergen and Greenland. 



Obviously, if we calculate the difference between the true course of the ship and the longitudes 

 where the ship was then located, it is not difficult to compute the direction change of the ship's cen- 

 terline for the period between the two determinations. For example from 30 June 1939 through 

 1 January 1940 the true course of the Sedov changed by 68.3°, while the longitude of the Sedou 

 changed 58. 5°. Consequently, the direction of the vessel's centerline changed by 9. 82 for this 

 period. 



This Indicates that the Sedov, despite all the zigzags and loops which it described along with 

 the drifting ice, moved almost parallel to itself, veering only slightly to the right (up to 13. 6°) and 

 to the left (up to 9. 8°) of the direction which it occupied on 30 June 1939. 



424 



