in case you need heavy duty canoe rack ? , the ones that sell's in the stores in piece's, are great but the rod's are light , if you want a rod / pole to be heaver [ stronger ] you can but in a piece of chrome molly tubing from a AIR CRAFT repaid shop, grease it up, you will need , a tree, 2 piece's of 2 X 4, a good heavy hammer to drive it together [ lots of work ]
when completed cut the ends off a use one a pop rivet in one end , to stop it from moving ,
# 1 --- need to put a bevel on one end of tube
# 2 --- have chrome molly tube about 7 to 10 inches longer than the rack

as you will bang one end with the hammer it will bend some .
the 2 x 4 against the base of tree , the second 2 x 4 to use as a buffer when you hit the other end of the chrome molly tube, have a 2nd person to help hold it to get started will help

PS THEY SELL THE TUBING THAT WILL FIT TIGHT , BUT WILL FIT WITH HELP