How to Build a Steel Pontoon

Steel pontoons are used for buoyancy under docks, barges and house boats. The sealed metal tube, even though it's heavier than water, stays afloat because of the dead air trapped inside. Crafting a metal pontoon from scratch can be a complicated process. However, you can fabricate a simple pontoon from a few old 55-gallon steel drums with a welder, and a few additional parts.

Things You'll Need

  • 3 steel 55-gallon drums
  • 5-inch disc grinder
  • Welder
  • Welding safety equip, including safety gloves and welding mask
  • 2 pcs 1 1/2-by-1 1/2-by-1/4-inch-thick steel angle iron
  • Sharpie marker
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Instructions

    • 1

      Grind any corrosion off the top and bottom rings of the 55-gallon drums. When the drums are welded together, any corrosion must be removed from the contact surfaces.

    • 2

      Insert a plug or cap in any open fittings on the tops of the barrels. The barrels must be sealed to create a pontoon. If a pre-fitted cap or plug is not available, weld a scrap piece of sheet metal over the opening.

    • 3

      Lie the three barrels down on a flat, level surface end-to-end, so they resemble a long cylinder. Weld the barrels together in that formation. Place 10 to 12 spot welds around the perimeter of each joint between the barrels.

    • 4

      Draw two lines down the entire length of the pontoon. Draw the lines 180 degrees apart from one another, so they bisect the pontoon laterally.

    • 5

      Weld the angle iron along these lines on each side of the barrel pontoon. The hydrostatic forces the pontoon encounters in the water create unpredictable torque forces on the barrels. These two pieces of iron strengthen the pontoon considerably, and give you a fastening surface to bolt the pontoon into a boat or dock.