FATHOMETER STUDIES 



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AGE OF WAKE IN MINUTES 



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Figure 8. Increase of wake echo duration for E. W. Scripps at 9.5 knots. Measurements of oscillograms. 



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AGE OF WAKE IN MINUTES 



Figure 9. Increase of wake echo duration for E. W. Scripps at 9.5 knots. Measurements on chemical recorder traces. 



asymmetry. The sailing vessel heeled over consider- 

 ably during the nms and the varying area of the hull 

 in contact with the water on either side was con- 

 sidered a cause for asymmetry. The wake of a twin- 

 screw vessel when both screws were turning and when 

 the wind was appreciable was then recorded. Again 



asymmetrical results were found. The effect is inde- 

 pendent of the direction from which the survey boat 

 crosses the wake. A typical value for the slope of the 

 bottom of an asymmetric wake, as found for a 125- 

 ft vessel, is 18 degrees. When the wind shifts from 

 port to starboard, the cross-section geometry of the 



