304 



Mr. E. W. Guclffcr on the 



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

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

 hand, the l)oat moves on top of a low hillock of water, 

 whieli she provokes, and she conseqnently moves on a nearly 

 horizontal surface, and meets with little lesistance. 



As to the modus ojterain/i by whicli a vessel in dead-water 

 rej^ains 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 piopulsion upon large boundary waves. Only if 

 the wind freshens still more, so that the propelling force 



Fi-. 10. 



l>iagianis from Scott-Russell, after Ekuiaii. 



A, boat towed at low .«ipeed, no disturbance and no marlted resistance; 

 B, at the critical speed, boat tendiii": constantly to rise on the 

 "solitary wave "and meeting with gre.'it re.-ii^tance ; C, boat's 

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

 wave and meets with no resistance. 



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

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

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

 from the dead-water.'' 



One other ex])lanation and we have finished with Ekraan. 

 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 Ekinan's interpretation given on page 301, 

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



