that the number of road changes and percent down time for moving equipment decreases as 

 tiie number of logs yarded on a given logging set increases. The cost per M bd.ft. de- 

 creased $1,568 for each 1 percent increase in percent productive hours as shown in equa- 

 tion (5) where cost was regressed on percent productive time 



C = 157.50 - 1.568P or in metric terms (5) 

 C = 34.81 - 0.3465P 



and = 0.7263. This relationship quantifies the cost of nonproductive time on this 

 logging operation. 



Equation (3) yields a simple but useful relationship for predicting yarding costs 

 based on both volume per acre and piece size. These two variables should provide a good 

 estimate since they explain 98 percent of the variability in cost based on the 1971 

 logging data. It should be kept in mind that equations (1) through (5) should be used 

 when the variables are within the range of the data given in table 1, and any extrapola- 

 tion should be used with care. 



These relationships based on gross data quantify factors that affect balloon log- 

 ging and should be followed through with a larger range of data so that the prediction 

 equations' range can be extended. Also, the equations should be verified by data from 

 other balloon logging sites. It is expected that these prediction equations would not 

 be as good for other areas since there are many factors which affect logging costs that 

 are not included in the equations. These factors can be more or less constant at one 

 logging site, but vary greatly between logging sites. Examples of some of these factors 

 are local wage rates, fuel costs, weather, terrain, timber type, and harvesting tech- 

 nique. Another factor to keep in mind when using the cost figures is that they should 

 be escalated for inflation because they are based on 1971 cost figures. 



As shown in table 2, balloon yarding costs ranged from S42.44 to $54.49 per M bd.ft. 

 If the site had been logged with a skyline (elevated cable) yarding system, costs would 

 have been about $20 per M bd.ft. Not included in the costs of skyline yarding is the 

 cost of the extensive road system required, which would have raised total costs 

 considerably. 



Yearly average cost and production figures did not vary greatly. It was hoped that 

 costs would decrease from year to year as experience with the balloon system was gained, 

 but this was not the case. Production did increase in the number of pieces per hour, 

 but the average piece size was smaller during the last year. Some of the more difficult 

 yarding chances were delayed until the latter part of the logging, and the sale was 

 completed using a helicopter for yarding. This modification to the original contract 

 was done with the approval of the Forest Service. The logging was done with a Boeing 

 Vertol-107 helicopter, which has a load capacity of approximately 8,000 lb (3,629 kg). 

 The helicopter logging subcontractor received approximately $90 per M bd.ft. ($19.89/m^) 

 to get the logs to the deck. This cost is higher than the average balloon logging cost, 

 but with the difficulty of the logging sets, it was felt to be justified. Also, the 

 production with this size helicopter is about 100 M bd.ft. (452 m^) per day, which is 

 approximately three times the balloon daily production; thus, the logging was completed 

 expeditiously. 



Based on the comparison of the helicopter and balloon logging, Boise Cascade decided 

 to sell their balloon logging system and bought their own helicopter. This decision was 

 based on the Forest Service plans to require aerial logging on substantial volumes of 

 timber in the southern Idaho Batholith. Evidently, Boise Cascade believed that owning 

 their own helicopter would be more economical --the production would be much greater and 

 the helicopter would be a more flexible system as compared to the balloon system in the 

 Idaho Batholith. 



15 



