114 BULLETIN 711, U. S. DEPARTMENT OF AGBICULTUEE. 



(2) The life of yarding engines is frequently shortened through 

 working them far beyond their efficient capacity, also through insuffi- 

 cient maintenance. 



(3) It is frequently prolonged through unprofitable care. 



(1) The industry has not kept cost records in such form as to 

 enable one in a given case to say confidently when the efficient life 

 has been passed. 



Most operators place the efficient life of ground yarding engines at 

 eight years. One of the leading operators of the region figures that 

 it is economical to work his j^arding engines hard for four years, sell 

 them, and buy new ones. Possibly he works them harder than any 

 other operator. If he can sell his engines at the end of four years 

 for one-half of their original cost, which he hopes to do, it would 

 seem that he figures on a life of about eight years. 



For the purpose of arriving at the amount that should be written 

 off annually for depreciation on this class of equipment, in connection 

 with the appraisal of national forest timber, the efficient life of 

 yarding engines has been placed at eight years, with a scrap value of 

 10 per cent of the original cost. 



ESTIMATING THE COST OF YAEDXNG, 



The following hypothetical statement will serve to summarize the 

 several items of expense in yarding and to show an estimated cost 

 of yarding per thousand feet on the basis of an output of 60,000 feet 

 per day per engine. It will also serve as a guide in estimating the 

 total cost of yarding, including labor, supplies, repair parts and mate- 

 rial, maintenance, depreciation, and supervision. 



Table 20. — Estimated total cost of ground yarding. 



Items. 



Labor cost 



Wire rope 



Rigginp 



Blocks, hooks, and rollers 



Fuel oil 



Lubncants, waste, and packing 



Depreciation on logging engine 



Maintenance of logging engine 



Woods water ?ystem 



Foreman, scaler, timekecjjer, and bookkeeper. 



Total . 



Total daily 

 cost. 



$39. 60 



Cost per 

 1,000 feet. 



$0.66 

 .136 

 .03 

 .02 

 .132 

 .01 

 .06 

 .04 

 .02 

 .04 



1.148 



The labor cost is based on an average daily output of 60,000 feet, 

 which takes into account both productive and unproductive time. It 

 is assumed that no extra yarding engine is used, which means that the 

 regular yarding crew moves the engine from one setting to another. 



