Cable yarding systems constitute an adapted solution for steep-slope harvesting in mountain forests. However, it requires many specific skills for both forest managers and operators. The objectives of this research were to 1) develop CableHelp model for the set-up of cable yarding systems where inputs are operational field data and outputs are load path and tensile forces and 2) to validate it with field experiments. The results show a high accuracy between the data predicted by the model and the field measurement. Furthermore, this work stresses out the importance of taking into account both the mainline effect and the friction between skyline and intermediate supports to properly calculate the skyline tension and load path. CableHelp model shows a great adaptability and ensures high accuracy predictions for any positions on the line profile and for different configurations: single span or multiple span profiles, uphill or downhill yarding and for different kinds of carriage. A direct application of this research is to optimize the set-up of cable lines in order to reduce the equipment wear as well as operating cost while respecting operator safety.