COST DATA 263 



On one occasion seven loads were removed during one day of 

 17i hours. The shortest time consumed in filling the hopper was 

 55 minutes. In dredging sand deposit in the channel, only four loads 

 per day could be removed under favorable circumstances ; the time 

 record being: 



Per Load. 

 Hrs. Min. 



Dredging 2 



Transport and discharge 1 10 



Mooring and unmooring 30 



Four loads at 3 hours 40 minutes 14 40 



Dredger in and out of port 1 20 



19 40 



The success of dredging at sea depends principally upon the 

 weather^ though the "Percy Sanderson," being of great size, can 

 work in a seaway up to 3 ft. high, when not on the beam. 



II 



Mr. Henry N. Babcock, M. Am. Soc. C. E., in Engineering News, 

 Vol. LVI, described the work of the two hydraulic hopper dredges 

 "Manhattan" and " Atlantic," used by the U. S. Government in 

 the improvement of the Ambrose Channel, New York. Concern- 

 ing the cost Mr. Babcock says: 



"Before July 1, 1905, the dredges were undergoing considerable 

 alterations and repairs to better adapt them to dredging the channel 

 material. They had removed 467,450 cu.yds. of material in eight 

 months' work of one dredge, and two months' of the other (total 

 ten months) at a field cost of 9.9 cts. per yd., as nearly as data at 

 hand show; some of the earlier bills were not paid from this office . 



"From July 1, 1905, to May 31, 1906, eleven months' work for 

 each dredge, they took out 3,258,707 cu.yds., at a field cost of 5.274 

 cts. per yd., the results from the two dredges being almost identical. 

 This cost is divided up, in reference to different parts of the work 

 done, as follows: 



Pumping 3.357 cts. = 63.66% 



Turning . 206 = 3 . 90 



Going to dump 0.835 = 15.83 



Dumping . 223 = 4 . 22 



Returning from dump 0.653 = 12.39 



5.274 cts. = 100% 



