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



steered before the wind, but she luffed and steered N. or E. A pilot boat of about 10 tons, 

 which she had in tow, was sucked in to the stern and could not be kept clear of it. As- 

 sistance was requested from a passing tug, which steered to the bow of the cutter to re- 

 ceive a hawser, but the two vessels were pushed from each other; the attempt was repeated, 

 in vain, and in order to come near enough to get the hawser aboard, the tug was obliged 

 to back astern to the bow of the cutter. 



"A vessel which is towed in dead-water does not answer her helm at all, and on the 

 river it is necessary to shorten the tow-rope, lest she should run aground or ashore; she 

 always strives to steer to the side, away from the course of the tug. Nor is it possible 

 to put the "wash" of the tug against the stem of the vessel in tow; it is pushed to the 

 side as shown by the figures. In dead-water it is better to use two tugs attached to the 

 vessel by short tow-ropes. Then a separate "wash" may be projected to each side of the 

 vessel and so "cut away or destroy the dead-water layer, so that it cannot cling to the 

 ship's side" 1 . In this manner two boats of 10 H. P. more easily drag a ship of 400 tons 

 than one boat of 20 H. P. 



"When the streaks or "dead-water waves" 1 , following the shores of the river, en- 

 counter a vessel at her moorings, they prove very powerful. When the first streak issuing 

 from the tug reaches the vessel, she is pushed forward (sucked back) 2 until the streak has 

 passed half the length or more of the ship; then she is drawn back (pushed on) 2 until 

 she is reached by the next streak when she is pushed forward (sucked back) 2 again and 

 so on. This is repeated with still greater force by the streaks issuing from the ship in 

 tow; and it has happened that vessels, moored for the winter, have broken their moorings 

 when a large ship has been towed down the river (in this case the force of the streaks is 

 greatest). When the tug and the ship have passed, the vessels on the banks continue to 

 swing to and fro, owing to the force of the successive streaks. The motion gradually 

 slackens, being perceivable for half an hour after the ship in tow has passed. 



"In the same manner, if the engine be stopped, the towed vessel herself stops short 

 and is then pushed backwards and forwards as she is reached by the successive dead-water 

 streaks. The streaks having passed by, the vessel may, in many cases, be got free from 

 dead-water, by making full speed ahead. 



"On the contrary, if, towing with a rather powerful tug, you wished to make a ship 

 fast in dead-water, you must begin to go at slow speed and then increase the pace very 

 gradually. In this manner it is possible to get so firmly fast that the ship cannot be got 

 free by the full pressure of the engine, without first stopping and letting the dead-water 

 streaks pass 3 ." 



No. 4. Mr. A. E. Tonnessen, Instructor at Grimstad, has kindly communi- 

 cated the following facts: 



"On the West port of Kristiansand (see the map on the upper left corner of PI. Ill) 

 dead-water often occurs in the summer, in calm weather or with easterly wind. Between 

 the town and Odder Island there is a channel, 3 or 4 m. in depth, through which the 

 water (river-water and salt water from the East port) almost continually flows out over the 

 West port. The ships, when leaving the town, must pass this stream of river-water and 

 there, athwart the channel, they often in calm weather get into dead-water. Among several 

 cases I have observed, the two following are the most remarkable. 



The sign of quotation is due to the present writer. 



In two separate letters these two different successions of the motions were stated. With 



regard to this order the account is therefore not quite reliable. 



When the author in May 1901 was at Fredrikstad to see the dead-water, Mr. Larsen 



on account of unfavourable circumstances did not succeed in getting fast in dead-water. 



Only a couple of very feeble dead-water streaks appeared and disappeared again. 



