why no 8ft on the Doyle Scale?

[loggerbro_80]

I was looking at the old Doyle Log Rule and noticed something weird, why is there no option for scaling an 8ft log? It seems to jump right over it!
Is there some historical reason for this gap? And more importantly, when you guys are out scaling, what's the correct way to handle an 8ft log? Do you double the 4ft measurement, or is there a trick I'm missing?

 

[cjmac163]

Not quite sure what you mean, but I am assuming you are looking at a copy that is missing the column for logs that are 8' in length. The Doyle Rule provides for scaling of logs in 2' length increments. Google "Doyle rule" and browse the photos until you find a copy that includes the 8' column.

If I got it all wrong, let me know. Would like to help you find the answers you're looking for!

Edit: To answer the second part of your question, I have never seen a column for a 4' log on the Doyle scale (most charts usually start at 6' or 8'), but in theory, yes. If you double the board feet for a 4' log, it will be pretty much the same volume as an 8' log of the same diameter. If I am not mistaken, the scale doubles the volume, but adds 1 board foot (I am taking this from the comparison between the 6' and 12' log columns)

 

[Steve Woodrow]

take half the 16'

 

[Rumgml3t]

I looked it up. the doyle rule doesn't have an 8ft log option because it's based on a formula where you subtract 4" from the diameter, square it, and then adjust for length in 16ft sections (or divide by 16), making 8ft logs just half the footage of a 16ft log of the same diameter, or you just scale them as 8ft logs using the same diameter logic but the formula is simpler for standard lengths

 

[Alan]

You got it. Doyle was built around 16ft logs and the formula subtracts 4 inches from the diameter, squares it, then scales by length in 16ft sections. An 8ft log is basically half the board feet of a 16ft log with the same diameter. You can scale it directly using the same logic, or just take half the 16ft value. That is why most charts skip an explicit 8ft column, it is just redundant mathematically.