The bottom 2" pipe is the full 21' length, and the top 1-1/2" pipe is about 17' long to give the total of 36' with the 2' overlap. The drawing to the left (not to scale) shows the base and some of the details of the assembly. The base is made of another 21' piece of 2" pipe cut in half to make a 10-1/2' long base unit. The pipes are spaced a little more than one pipe diameter apart and secured by welding 3/16" X 2" steel strap between them. The mast pivots on a 3/8 X 8" bolt at the base midpoint just above ground level (dashed rectangle). This leaves about 5' of base both above and below ground.