304 



Mr. E. W. Gudger on the 



just as if she constantly had to rise on an incline. She is 

 then ' in dead-water/ ' At the higher velocity on the other 

 hand, the boat moves on top of a low hillock of water, 

 which she provokes, and she consequently moves on a nearly 

 horizontal surface, and meets with little resistance. 



As to the modus operandi by which a vessel in dead-water 

 regains her speed, Ekman takes the case of a sailing-vessel 

 which has taken dead-water because of a drop in the wind. 

 "If the wind now recovers its initial strength, the only 

 effect is that the vessel has her velocity increased a little 



, but she still lies in dead-water and consumes her 



energy of propulsion upon large boundary waves. Only if 

 the wind freshens still more, so that the propelling force 



Kff. 10. 



Diagrams from Scott-Russell, after Ekman. 



A, boat towed at low speed, no disturbance and no marked resistance; 

 13, at the critical speed, boat tending constantly to rise on the 

 "solitary wave "and meeting with great resistance; C, boat's 

 speed exceeds the critical velocity, boat rides on top of solitary 

 wave and meets with no resistance. 



gets the better of the mnximum resistance . . . . , is her 

 velocity at once increased . . . . ; and the large boundary 

 waves simultaneously disappear .... the vessel has got free 

 from the dead-water."" 



One other explanation and we have finished with Ekman. 

 It has been noted repeatedly that vessels in dead-water refuse 

 to obey the helm. If now one turns to Capt. Kroepelien's 

 account and to Ekman's interpretation given on page 301, 

 the explanation is apparent. Boat, rudder, and the surface 



