Abstract:
This paper describes the results of a time-study conducted
near Grand Ronde, Oregon, to determine the production
rates and total harvesting costs of a cable thinning in a
young stand. The stand had a species mix of 48 percent
western hemlock (Tsuga. heterophylla- (Raf.) Sarg.), 45 percent
Douglas-fir (Pseudotsuga meuziesil (Mirb.) Franco), and
7 percent white fir (Abies concolor (Gord. & Fiend.) Lindi.).
The stand had an average age of 33 years, with a mean dbh
of the total stand (over 1.5 inches (3.8i cm) dbh) of 5.7
inches (14.48 cm). The mean dbh of the merchantable stems
(over 6 inches (15.84 cm) dbh) was 8.3 inches.
The yarder belonged to the small size class of yarders,
and was rigged with a live skyline system using a selfclamping,
manual slack-puliing carriage. Three hooking
techniques consisting of three chokers with sliders, presetting
three ring chokers andusing a toggle hook, and
flying six ring chokers per turn were compared on a production
basis.
Regression equations were developed for the individual
elements of the yarding cycles and for total cycle times
ftr each hooking technique. Results indicate that there is
no significant difference between the production rates of
three chokers and sliders compared with three preset
ring chokers and a toggle hook. There was a significant
difierence between the production rates when using the three
chokers and sliders compared with using six ring chokers
and a toggle hook. The six ring chokers and toggle hook
was about 13 percent faster per MBP.
The total harvesting cost was compared with the mill
value of the timber. The total harvesting cost included
felling, limbing, and bucking cost, equipment move-in and
move-out cost, yarding cost, loading cost, and hauling
cost. Not included in the harvesting cost was road costs,
engineering and layout costs, timber tax costs, or any
profit and risk costs. The total harvesting cost came to
$227.90 per MBP. The weighted average mill price for the
logs was $250.24 per MBP.
