Measuring log length with Suunto clinometer

Measuring Log Length with Suunto Clinometer Model PM 5 – 66.

• Find a position where both the top and the bottom of the log can be clearly seen. Take readings to the top and the bottom of the log on the right side (feet) scale of the Suunto and add or subtract readings as follows:

• While taking these readings have a line cut to the base of the tree and measure the distance to the tree in feet (length of base line) and the slope along this line in degrees (slope of base line) on the left-hand scale of the Suunto. • Obtain the true log length in feet by using the tree height wheel. Turn the wheel until the reading for slope of baseline in degrees is opposite the reading for length of baseline in feet. Then find the total height reading in feet on the “Instrument Reading” scale. Opposite this on the “tree height” scale will be the log length in feet. • The accompanying figure is an example of the use of the tree height wheel. • N.B. If the tree is to be measured is not growing vertically but has an obvious lean, then do not stand in front of or behind the lean to take height readings, because this may cause serious errors. The estimator must note which way the tree is leaning and stand in a position at right angles to the plane of lean (i.e., at right angles to the direction in which the tree would probably fall if cut down).

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7 Archer, G.R. 1972. A simple tree height converter [for measuring tree heights in steep topography with poor visibility]. Commonwealth Forestry Review 51(3): 246-253.