22 EKMAN. ON DEAD-WATER. [norw. pol. exp. 



(the vessel was capable of making 8 knots). The force of the wind was constant during 

 the whole time." — — — — — — — — — — — — — __ — _.— 



"When the ship is moving ahead, leaving a void space astern, the fresh-water on the 

 surface rushes in from aft to fill the wake, thus tending to reverse the action of the rudder; 

 the steering of the ship is, in consequence, destroyed. In fact the fresh-water can be seen 

 rushing after the ship and it makes a great noise." 



Effects of dead-tvater and surface-currents combined. 



No. 13. I am indebted to Kommendorkapten F. W. L. Sidner of the 

 Swedish Navy, for a verbal account, which he has been good enough to revise, 

 of the following interesting accident. 



"In July 1899 I was on my way with the corvette Freja from Carlscrona to Leith. 

 The Freja is a ship of 2000 tons' displacement, 66 m. in length, 12 m. in breadth and draw- 

 ing 6 m. Besides sails she is furnished with engine and screw-propulsion, hut this was not 

 used in the case mentioned here below. 



"On July 11th in the evening, the Freja was running before a southerly breeze from 

 Lceso towards Skagen. 



"The breeze, being rather light, was dying down but still gave a speed of 3 or 

 4- knots. At 7 p.m. — the ship was then probably about 7 miles SE. of Skagen — she got 

 into dead-water, which at first mainly manifested itself by bad steering. At midnight the 

 dead-water became more decided, and the speed was reduced. The ship, then about 5 miles 

 east of Skagen, was heading northward before the wind, and her course had to be changed 

 to west. She answered her helm and turned through two points, heading NNW., but she 

 could not be brought further westward. An attempt was made to turn her round the other 

 way through north, east, and south to west. She answered till she got two points from 

 the wind — SSE. — , but then the sheer stopped, and she fell off in spite of the action of 

 sails and rudder. These attempts were repeated several times, with just the same result; 

 within the semicircle NNW.~E.-SSE. the ship could be steered, but not beyond these 

 limits. She could not be brought to head westward, and we got farther and farther from 

 Skagen. 



"During this involuntary northward sailing, peculiarities were observed in the sur- 

 rounding water (see Fig. 14, PI. IV) 1 . Before the bow on the port side, a low hillock or 

 bank of water was formed at a short distance from the ship's side. Inside this bank and 

 along the whole port side of the ship, the water was "boiling". All the way starboard of 

 the ship the water had the appearance of an eddying current. Furthermore, the ship was 

 followed by two sharply defined wakes, the one slightly curved to the port side and the 

 other more strongly bent to starboard; between them the water was agitated. 



"At half past two next morning, a steam- trawler was seen, heading straight for the 

 Freja, which lay still helpless, though the wind had increased. As sailors believe that a 

 steamer can shake another vessel free from the dead-water, we waited with interest to see 

 whether the trawler would come near enough to do us this service. She had the trawl 

 in tow and, therefore, could not have made more than about 3 knots. She advanced to a 

 distance of about l'/2 cable's length (300 m.) and then turned round and went back again; 

 and actually, when she was closest to us, the Freja suddenly got rid of the dead-water 

 and sailed at a good speed, which after a while was logged as 6"2 knots." 



1 The sketch was made by the present writer and afterwards corrected by Kommendfir- 

 kapten Sidneh. 



