Finding usable tree height is accomplished using a clinometer. This device, which can be an app for Android and iOS devices, provides angles to deduce usable tree height for milling trees. After finding the percentage angles, subtract the base angle (negative value) from the angle where the usable tree height ends. Do not forget to change percentages to decimal form or the tree height will be incorrect. Multiply this result by 66 feet to determine the usable tree height. This measurement is needed to find the board feet available in the tree.
You also need to measure the circumference of the tree at chest level, roughly 4 1/2 feet from the ground. Convert this to diameter using the formula: diameter = circumference/3.14. Convert this from inches to feet by dividing by 12 and then find the radius by dividing by 2. The next step is finding cubic feet to estimate board feet.
Thank you for posting an informative and interesting article on the determination of board feet from standing timber.
ReplyDeleteOne thing that we need to caution users of is to make certain to use proper number format for percentages. For example, in the problem in your post, the slopes are 46% and -5%. For calculation purposes, these are .46 and -.05. If percentages are not formatted correctly, the tree in your example would be 3370 feet rather than the correct 33.7 feet.
Thanks Steve. I changed the percentages to decimal form to limit the confusion.
ReplyDeleteVery cool posting! The picture makes it a lot easier to understand (especially when you are not a "math person"). Thanks Jason. I'm going to copy this off. Thanks a bunch!!
ReplyDeleteGood post Jason. You made it easy for students to understand, particularly with the picture.
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