United States 

Department of 

Agriculture 

Forest Service 

Northeastern Forest 

Experiment Station 

Estimating Yarding Costs 

For the Clearwater Cable Yarder 

Chris B. LeDoux 
Abstract 

Describes an equation that can be used to estimate yarding costs for the Clearwater cable yarder in clearcuts and light and heavy thinnings in eastern hardwoods. Yarding costs can be estimated with a hand-held calculator or the data 

can be incorporated into stump-to-mill desktop and mainframe computer 

programs. 

The Author 

CHRIS B. LeDOUX is an industrial engineer and Pr~ject Leader with the Northeastern Forest Experiment Station at Morgantown, Nest Virginia. 

Manuscript received for publication 21 August 1987 

Northeastern Forest Experiment Station 

370 Reed Road, Broomall, PA 19008 

November 1987 
Introduction 

Recent interest in promoting cable logging technology in 

the Eastern United States (Paul 1980; VPI&SU 1982) has led 

to production tests for and the development of a detailed, 

stump-to-mill costestimating package (LeDoux 1985) for 

six cable yarders of various sizes and capacities. These 

include the Appalachian Thinner, Bitterroot, Ecologger I, 

Koller K-300. Skylok 78, and Urus 1000-3. The cost equations for stump-to-mill timber production reflect conditions 

that would be encountered when logging hardwoods on 

steep, mountainous terrain in the Eastern United States. 

A seventh system, the Clearwater yarder developed by the 

USDA Forest Service (USDA Forest Service 1981), was field 

tested in the Eastern Adirondack region of New York State 

(Bragg 1985; LeDoux and Peters 1985) and elsewhere (Till 

1980; Sherar and Koger 1984), and subjected to comparative analysis (Sherar 1980; Walbridge et al. 1980; Gorsh 

1 983). 

For this study, detailed time and motion data from the New 

York field studies, 1987 new equipment, labor, and fuel costs 

(Table I), and the THlN yarding simulation model (LeDoux 

and Butler 1981) were used to develop a general equation 

for estimating yarding costs for the Clearwater yarder in 

Table 1.-Hourly yarding costs (1987) for the Clearwater 

yarder (includes all new equipment) 

Item Dollarslhr 

Yarder and truck 

carrier 38.05" 

Chain saws (3) 3.58 

Labor 27.00b 

Carriage 0.67 

Radio signal 

(3 transmitters) - 1.15 

Total 70.45 

"Includes depreciation, insurance, interest, and operating 

costs (fuel, oil, lubricants, maintenance, repair, taxes, and 

rigging) for the yarder and carrier. 

"One yarder engineer, two chokersetters, one chaser; rates 

from "Cost Guide for Empirical Appraisals," USDA Forest 

Service, Region 9, Amendment 112. 

eastern hardwoods for various stand conditions and silvicultural treatments. The cost equation was then used to compare the Clearwater yarder with the six previously 

mentioned systems. 

Yarding Cost Equation 

Simulated, delay-free data points for yarding cost were 

developed for the Clearwater yarder for a range of diameters (DBH), average slope yarding distances (SYD), and 

volumes cut per acre (VOAC). The stands chosen were 

from forest model plots of eastern hardwoods (Table 2). 

Each stand was thinned using a d/D ratio (arithmetic mean 

diameter of cut treedarithmetic mean diameter of stand) of 

1.0 to levels of 30 percent, 50 percent, and then clearcut. 

The trees cut from each treatment were bucked into logs1 

(LeDoux 1986). The THlN model (LeDoux and Butler 1981) 

and time-study data cited previously were used to develop 

the delay-free data points through numerous simulations. 

The simulated data points were pooled to develop a delayfree cost equation for the Clearwater yarder. Nonlinear 

Table 2.-Stand data for eight forest model plots 

Average Merchantable No. trees 

Plot d.b.a." volumeb per acre" 

Inches Ft3 

A2 7.2 2652 222 

B10 8.1 2528 214 

C8 9.1 3556 245 

Dl 4 11.6 31 24 166 

El 3 12.7 4922 1 83 

F4 16.8 6315 176 

G4M 20.4 6466 1 62 

H4M 24.0 6871 174 

"Includes trees 5.0 inches or larger in d.b.h 

"Logs less than 4 feet long and less than 4 inches top 

diameter not included. 

ILeDoux, C. B. 1984. Hardwood log bucking simulator. 

Unpublished computer program on file at the Northeastern Forest Experiment Station, 180 Canfield Street. P. 0. 

Box 4360. Morgantown, West Virginia 26505. 
multiple regression analysis was used to summarize the 

delay-free data points and the independent variables: 

Dollardfts = 0.1 2577 

- 0.00328 (DBH) 

+ 0.000048 (SYD) 

+ 623.08404 (l/(VOAC * DBH)) 

R* = 0.582 

where: 

DBH = Arithmetic mean tree diameter at breast height, in 

inches; variable limits = 4 to 16 inches 

SYD = Average slope yarding distance, in feet; variable 

limits = 50 to 900 feet 

VOAC = Average volume removed per acre, in ft3; variable 

limits = 780 to 6,871 ft3 

The equation is machine-specific and the variable limits 

should be observed carefully. 

The delay-free cost must be adjusted to allow for nonproductive time. Delay percentage is the proportion of nonproductive time expressed as a percentage of total time. One 

minus the proportion of nonproductive time is the proportion of productive time. For example, if the delay is 10 percent, the proportion of nonproductive time is 0.1, and the 

proportion of productive time is 0.9. The delay-free cost is 

adjusted by dividing it by the proportion of productive time 

to obtain the cost with delay. 

Yarding Delays 

The observed productive time for the Clearwater yarder was 

only 40 percent of total time; however, this low time was due 

to the unexpected (and rare) breakdown of the skyline and 

mainline. Eliminating this delay would result in a productive 

rate of nearly 60 percent, which compares favorably with 

the other cable systems mentioned (LeDoux 1985). Productive delays accounted for 14.5 percent of total time and 

nonproductive delays 45.5 percent. The following is a 

breakdown of the nonproductive and productive delays with 

the Clearwater yarder: 

Delay 

Nonproductive 

Broken skyline 

Broken mainline 

Loose hydraulic hose 

Fix stop 

Miscellaneous 

Total 

Productive 

Hangups 

Wait on skidder 

Move stop 

Tangled mainline 

Hit stop 

Slipped choker 

Total 

Percent 

The delay percentages can be used to adjust the delay-free 

cost estimates. For example, a logger is estimating yarding 

costs for a hardwood stand with an average arithmetic tree 

d.b.h. of 8.0 inches, an average slope distance of 200 feet, 

and an average volume removal of 2,000 ft3. The delay-free 

yarding cost is: 

= 0.12577 

- 0.00328 (8) 

+ 0.000048 (200) 

+ 623.08404 (1/(2000 * 8)) 

= 0.148 

Adjusting the delay-free cost with an average delay 

percentage of 0.23 (LeDoux 1985) = 0.148(1-0.23) = 

0.148/0.77 or $0.192/ft3. Users may wish to substitute delay 

percentages based on their own observations. 

Applying the Cost Equation 

Yarding costs can be estimated with a hand-held calculator 

or the data can be incorporated into stump-to-mill desktop 

and mainframe computer programs, Information on the 

arithmetic mean d.b.h. to be harvested, average slope yarding distance, and average volume cut per acre can be 

obtained from the inventory and cruise data and the logging 

plan for the tract. Figure 1 shows the impact of silvicultural 

treatment on yarding cost. Heavy-volume removals reduce 

yarding costs; the reverse is true for low removals. Information such as that in Figure l also can be used to plan harvesting limits. For example, a logger is allowed $0.12/ft3 for 

the yarding operation. Projecting a line representing O.l2/ft3 

on Figure 1 shows that the break-even points require harvesting limits of 9.5,12.0, and 14.5 inches d.b.h. for clearcuts, heavy, and light thinnings, respectively. 

Clearwater Versus Other Yarders 

The Clearwater Yarder is competitive with the Appalachian 

Thinner in the d.b.h. range of 7 to 10 inches, and with the 

Koller K-300 and the Ecologger I in the range of 7 to 16 

inches (Fig. 2). It is important to note that the competitive 

ranking of these machines will be affected by differences in 

factors such as initial investment, salvage value, crew size 

required, payload capacity, and line speed. Also, the comparisons shown are based on specific sets of stand conditions and will change accordingly with changes in slope 

yarding distance and volume removal. 

Because of its limited capacity (3,500 pounds), the Clearwater yarder cannot bring in heavy loads to increase production and reduce the cost per unit produced. In this 

study, the actual working payload was about 1,250 pounds, 

rather low for a system that costs about $95,000. Also, the 

limited mainline pull (7,500 pounds) of this machine 

resulted in significant delays in breaking the turn of hooked 

logs from their lay. Sherar and Koger (1984) reported that 

increased mainline pull would result in fewer delays. 
AVERAGE D.B.H., inches 

Figure 1.-Simulated yarding cost and break-even points by 

silvicultural treatment for the Clearwater yarder. 

. BITTERROOT A-A 

I KOLLER K-300 0-0 

APP. THINNER 0-0 

SKYLOK 78 -. 

I 

URUSl000-3 x-* -*\ 2 ECOLOGGER 1 1-1 

CLEARWATER +-t -0 

1. 

.-. -*-0-* '+\ 

y,-*-*--.-

'+, *-X-x \ 

16 18 2 0 2 2 24 

AVERAGE TREE D.B.H. IINCHES 1 

Figure 2.-Simulated comparison of seven cable yarders by average tree d.b.h. (SYD = 

200 feet; VOAC = 2,000 ft3). Shaded areas indicate diameter range best suited 

for individual machines. 
Literature Cited 

Bragg, W. C. 1985. Productivity and cost of the Clearwater 

yarder in the Eastern Adirondack region of New York 

State. Syracuse, NY: State University of New York, College of Environmental Science and Forestry. 11 1 p. M.S. 

thesis. 

Gorsh, J. W. 1983. Efficient use of small timber systems. In: 

Proceedings, timber harvesting in the Central Rockies: 

problems and opportunities; 1983 January 4-6; Fort Collins, CO. Publ. XCM-87. Fort Collins, CO: Colorado State 

University, Cooperative Extension Service. p. 133-141. 

LeDoux, C. B. 1985. Stump-to-mill timber production cost 

equations for cable logging eastern hardwoods. Res. 

Pap. NE-566. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 6 p. 

LeDoux, C. B. 1986. Bucking logs to cable yarder capacity 

can decrease yarding costs and minimize wood wastage. 

Southern Journal of Applied Forestry. 10: 180-183. 

LeDoux C. B.; Butler, D. A. 1981. Simulating cable thinning 

in young-growth stands. Forest Science. 27(4): 745-757. 

LeDoux, C. B.; Peters, P. A. 1985. Computer planning tools 

applied to a cable logging research study. In: Proceedings, improving mountain logging planning, techniques 

and hardware: a joint symposium of the IUFRO mountain 

logging section and the 6th Pacific Northwest skyline 

logging symposium; 1985 May 8-11; Vancouver, BC. 

Vancouver, BC: Forest Engineering Research lnstitute of 

Canada. p. 51-54. 

Paul, J. G., ed. 1980. Proceedings, 1980 cable yarding conference; 1980 September 9-10; Asheville, NC. Asheville, 

NC: Hardwood Research Council; Norris, TN: Tennessee 

Valley Authority, Division of Land and Forest Resources. 

151 p. 

Sherar, J. R. 1980. Comparison of skyline and ground-based 

harvesting systems. In: Proceedings, 1980 cable yarding 

conference; 1980 September 9-10; Asheville, NC. Asheville, NC: Hardwood Research Council: Norris, TN: Tennessee Valley Authority, Division of Land and Forest 

Resources, p. 128-145. 

Sherar, J. R.: Koger, J. 1984. The Clearwater yarder: A Mississippi case study. In: Peters, Penn A.; Luchok, John, 

eds. Mountain logging symposium proceedings; 1984 

June 5-7; Morgantown, WV. Morgantown, WV: West Virginia University. p. 337-349. 

Till, K. 1980. Lightweight cable systems yard slash for firewood. Spec. Rep. Missoula, MT: US Department of Agriculture, Forest Service, Equipment Development Center. 

11 p. 

U.S. Department of Agriculture, Forest Service. 1981. 

Clearwater yarder operations manual. Man. 81 -2602. 

Missoula, MT: U.S. Department of Agriculture, Forest 

Service, Equipment Development Center. 18 p. 

Virginia Polytechnic lnstitute and State University. 1982. 

Proceedings, Appalachian cable logging symposium; 

1982 January 12; Blacksburg, VA. Blacksburg, VA: Virginia Polytechnic Institute and State University. 72 p. 

Walbridge, T. A.; Griffeths, R. C.; Stuart, W.V. 1980. Big 

yarders, big roads-small yarders, small roads. In: Proceedings, 1980 cable yarding conference; 1980 September 9-10; Asheville, NC. Asheville, NC: Hardwood 

Research Council; Norris, TN: Tennessee Valley Authority, Division of Land and Forest Resources. p. 93-102. 
LeDoux, Chris B. 1987. Estimating yarding costs for the Clearwater yarder. 

Res. Pap. NE-609. Broomall, PA: U.S. Department of Agriculture, Forest 

Service, Northeastern Forest Experiment Station. 4 p. 

Describes an equation that can be used to estimate yarding costs for the 

Clearwater yarder in clearcuts and light and heavy thinnings in eastern 

hardwoods. Yarding costs can be estimated with a hand-held calculator or 

the data can be incorporated into stump-to-mill desktop and mainframe 

computer programs. 

ODC 377.2 (74/75) 

Keywords: Yarding costs, simulation, delays 
Headquarters of the Northeastern Forest Experiment Station are in Broomall, Pa. 

Field laboratories are maintained at: 

a Amherst, Massachusetts, in cooperation with the University of Massachusetts. 

a Berea, Kentucky, in cooperation with Berea College. 

a Burlington, Vermont, in cooperation with the University of Vermont. 

Delaware, Ohio. 

a Durham, New Hampshire, in cooperation with the University of New Hampshire. 

a Hamden, Connecticut, in cooperation with Yale University. 

a Morgantown, West Virginia, in cooperation with West Virginia University, 

Morgantown. 

Orono, Maine, in cooperation with the University of Maine, Orono. 

Parsons, West Virginia. 

a Princeton, West Virginia. 

a Syracuse, New York, in cooperation with the State University of New York 

College of Environmental Sciences and Forestry at Syracuse University, 

Syracuse. 

University Park, Pennsylvania, in cooperation with the Pennsylvania State 

University. 

Warren, Pennsylvania. 

Persons of any race, color, national origin, sex, age, religion, or with any handicapping condition are welcome to use and enjoy all facilities, programs, and services 

of the USDA. Discrimination in any form is strictly against agency policy, and 

should be reported to the Secretary of Agriculture, Washington, DC 20250.