Things You'll Need
Instructions
Multiply the outside pipe diameter in feet by itself using a calculator and call it "D." Assuming the diameter to be 1.5 feet, D = 1.5 X 1.5 = 2.25.
Multiply "D" with 62.4 (the weight of water in pounds-per-cubic-foot) and call it "D1." For the example being considered, D1 = D X 62.4 = 2.25 X 62.4 = 140.4.
Multiply "D1" with 0.78 (the percentage of the pipe which is submerged in the water) and call it "W." For the example being considered, W = D1 X 0.78 = 140.4 X 0.78 = 109.51.
Multiply "W" with the length of the pipe to get the required buoyant force in pounds. Assuming the length of the pipe to be 5 feet, the force will be F = W X 5 = 109.51 X 5 = 547.55 pounds.