How to Build a Pulley for a Sail

A sail pulley design requires the mechanism to not only work as a wheel joint for a rope, but to also be able to withstand the weight of the sail being pulled up or lowered via the pulley. This requires the materials of the unit to be stronger than decorative wood or plastic. Additionally, the pulley will need to be able to withstand the elements, being regularly exposed to both water and air. Thus it needs to be corrosion resistant as well. The construction process involves simple steps, which is why pulleys have been used by sailors and boat-builders for centuries.

Things You'll Need

  • 2 egg-shaped metal plates, 2/8 inch thick
  • Power drill and metal drilling bits
  • 1/2inch diameter metal tubes
  • Hacksaw
  • 2 cotter pins
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Instructions

    • 1

      Determine whether the pulley will be for the top mast hoisting or will function as a deck angle pulley. Plan on using a larger pulley if it will be for a top mast function.

    • 2

      Obtain two flat plates of stainless steel at least 2/8-inch thick and shaped like an egg. Use a power drill with a metal-drilling bit to drill a ½-inch diameter hole in the smaller end of each plate. Drill another ½-inch diameter hole in the center of the bigger part of each plate.

    • 3

      Find two metal tubes with a ½-inch diameter thickness and with a flared end on one side. Cut the tubes to a 2 -inch length, leaving the flared end alone. Use a hacksaw to sever the tubes. Insert the tubes in the first plate, confirming they don’t insert all the way through and stop at the flared end.

    • 4

      Pull the cut tubes out and drill the end with a 1/8-inch drill bit. Puncture the non-flared end of the tube all the way through from one side to the other.

    • 5

      Place the tubes back into the first plate, and lay the plate flat on a table with the inserted tubes sticking upward. Size a 1-inch-thick wheel with a ½-inch center cavity to the tube in the larger half of the plate, using the tube as an axle for the wheel. Insert the wheel on the tube.

    • 6

      Apply the second plate on top so that the wheel is sandwiched between the two plates. Make sure only the two tubes insert through both plates, with the drilled ends sticking out. Insert two cotter pins into the tubes, one in each drill hole on the tubes’ ends. Bend the cotter pin as it sticks out the other side of each tube, so that the pin stays in place.

    • 7

      String up or bolt the pulley where it will be located on the boat mast or hull and route the sail rope through the pulley’s wheel. Pull or lower the sail as necessary.