STRAIGHTPOINT’S Impact Block has been proving its worth as a training device in Finland, filling gaps in knowledge about the forces put through rigging equipment and the weight of loads as they are cut away from trees.

The tool utilises wireless dynamic load monitoring electronics and strain gauge technology to measure the shock load and weight of branches as they are cut during tree felling or maintenance. Real-time data can be displayed on a handheld controller, tablet or laptop at speeds up to 200 Hz. This eliminates the estimation work that often goes into arborist applications.

Forestry Journal:

Mika Vainionpää, a climbing teacher at Finnish arborist school Sedu (based in Ähtäri), said: “Unlike crane-related or other typical rigging scenarios, in tree applications professionals do not always have an anchor point above the lifting point. It’s a type of negative rigging. Every tree is different. There are no labels in a tree that say to the climber how much the rig can take. You have to study and learn where those limits are. Branches are one thing—leaves and smaller branches can limit the force—but logs can be more unpredictable.”

Forestry Journal:

Vainionpää, who also owns an arborist company (, recently utilised a 60 kN version to measure how big the heaviest weights are during a normal climb and recorded the weights of the top and base anchors. Impact Block can be installed at the top of a tree or lower in the canopy before starting to cut limbs off. Vainionpää said he predominantly uses 12 mm or 14 mm Teufelberger Sirius Bull ropes.

Forestry Journal:

He added: “The Impact Block adds weight and rigging to our projects, but that is outweighed by the education it gives us. Trees are very complicated and normal rigging rules don’t apply. However, we are at the lower end of our learning curve with this technology and must continue to conduct tests and deliver education before it can make a widespread difference across arboriculture. For that reason, it remains more of a training product than a site-only tool.”

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