EXCAVATING MACHINERY USED IN LAND DRAINAGE. Dal 
An engineer, a craneman, a fireman, and one or more deck hands are 
required to operate a dipper dredge. The output, loss of time due to 
breakdowns, and cost of repairs depend almost wholly upon their skill 
and efficiency. The engineer should be an all-round mechanic, expe- 
rienced in dredging. The cost of repairs depends largely upon the 
operator; a careless operator will cause unnecessary breakdowns. It 
is not only repairs of machinery but also the time lost that increases 
the cost of the output. It is well established that it is not the initial 
cost of a dredge or of any machine that consumes the profits, but, 
rather, the operating and overhead expenses. So important a matter 
is the efficiency of the operator and craneman that where mosquitoes 
are troublesome electric fans are often used. 
COST OF OPERATION. 
The cost of dredge work depends upon a number of factors: The 
locality of the work, the kind of soil, repairs, delays, labor, etc., influ- 
ence the actual cost of any work. If the water level can naturally be 
maintained within a foot or so of the surface of the ground the cost 
of excavation can be reduced very low with this type of machine. 
One great item is labor cost. 
To obtain economical results there must be a certain minimum 
yardage for the dredge to remove, for installation charges must be 
included in the cost of the work. Any excess in yardage over this 
minimum would reduce the cost per cubic yard, but this unit cost 
decreases very slowly as the yardage increases and finally becomes 
practically fixed. 
Table 9 gives for each size of dredge the size of job above which an 
increase In amount of excavation will not result in an appreciably 
lower cost per cubic yard, as well as the average output per month, the 
average coal consumption per 10-hour shift (using a good grade of 
coal), and the time and number of men required to erect and dis- 
mantle. 
TABLE 9.—Data useful in estimating cost of excavation by floating dipper dredge. 
| 
Number of men and time required— Average 
U 1 Mini Oper a ae 
. sua Minimum coa 
aire ee length of | ; economical aon consump- 
De boom. | To assemble dredge with | po gismantle dredge. yardage. | gonble | tion per 
old hull. : 
shift 
\(52shifts) 
| | 3s wet i 
Cu.yds.| — Feet. Cu.yds. Cu.yds. Tons. 
a 30 | 8 men, 30 days!.......... 8 men, 14 weeks........- 100, 000 20, 000 13 
1 40 | 10 men, 2 months........- 10 men, 3 weeks....-....- 300, 000 27, 000 2 
13 50 | 12 men,2 months.......- 12 men,3 weeks....-.-.- 500, 000 37, 000 3 
2 55 | 12 men, 34 months......: 12 men,14 months...... 800, 000 47,000 34 
23 65 | 15 men, 34 months....... 15 men,14 months...... 1,000, 000 55, 000 33 
3 80 | 20 men, 6 months. .-...-.. 20 men, 2 months..-.--- 1, 500, 000 70,000 4 
BY SOs S52 C0 AO eas aes ee ar ae Glo: 5a Saree ae a 2,000, 000 75, 000 “44 
43 90 3,000, 000 80, 000 6 
1 Dredge equipped with steel pontoon hull. 
