THE COST OF OPERATING DREDGES 255 



In the sea-going hopper dredge the most important operating 

 expenses are the wages of the officers and crew handling the machine. 

 As a rule there are always two crews on board of these steamer 

 dredges, in order to work continuously day and night. Other 

 important items of expenses are the consumption of coal ; the repairs 

 which are absolutely necessary to keep the machines in good working 

 order; the subsistence of the crew and officers compelled to live on 

 board the steamer; besides miscellaneous supplies, as water, etc. 

 In the sea-going hopper dredge either of the hydraulic or ladder 

 types, the various items of the operating expenses are more or less 

 in the following proportions: 



Wages 33% 



Coal 25 



Repairs 25 



Subsistence 10 



Miscellaneous 7 



Total 100% 



When the dredged materials are transported to the dumping 

 place by means of scows towed by tugboats, the cost of transpor- 

 tation represents the highest item of the operating expenses. Dredges 

 served by scows as a rule work only in daytime, consequently one 

 crew is sufficient to handle the machine during its work; thus the 

 expenses concerning the. wages of the crew and their subsistence 

 are comparatively small. In general it may be said that in dredges 

 served by scows the various operating expenses are in the following 

 proportions : 



Transportation of scows 40% 



Wages 22 



Repairs 18 



Coal 12 



Board 6 



Miscellaneous 2 



Total 100% 



In dredging, the coal consumption is comparatively a small item 

 when compared with other expenses. Consequently high-tower 

 ladder dredges are not as uneconomical as they seem, and could be 

 more extensively used to advantage in some particular cases. For 

 making a rough estimate the coal consumption can be figured about 

 1 cent per cubic yard of dredged material, provided the price of coal 

 is $3.00 per ton. 



