Jim, The rails used were not polished de-barked posts. They were rough split fence rails. (An axe or wedge was driven into the end of a pole and forced into it until it split into two pieces. Each of those was then split again one or more times until they were the desired size. This left sharp splintery edges which were definitely not comfortable to sit on! Imagine a circle divided into four or more parts and that extended along the length of a pole!) The tar used in shipbuilding was usually pine tar which definitely isn’t the same as asphalt tar. Although the process you described is probably a bit in error, the sentiment definitely applies!
It is always good to be accurate at all times and I can always expect just that from my buddy! After all "close" only counts in horseshoes and washers.