This paper provides evidence of improvement in cable yarder operator proficiency through initial training on a controlled site. Five subjects were included in the study: one expert (as control), two with limited experience in operating similar machines, and two with no experience. A 1:3 scale tower-yarder modeled on the Owren 400 was used as a test rig. A wireless control with two joysticks, used individually and in combination, covered all yarder and carriage functionality. The time taken to individually yard five logs was measured and repeated six times over two days for each subject. Cable tension in the system was simultaneously monitored as an indicator of operating consistency.Evidence of a distinct learning curve was obtained through statistical analysis by applying mixed-effects models. The standard deviations of times and tensions of the limited-experience group rapidly emulated the profiles of the expert, and subjects in the no-experience group were comfortable with the operation of the yarder controls after the six trial replications.A reduction in initial large fluctuations in cable tension demonstrated the useftilness of training. On-the-job training with full-scale machines under similar conditions could have led to system failure, with possible breakage of the tail spar, guy lines or mainline and potential material loss and human injury.
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