How to Build Boat Windows

Boat windows are made from durable plastics such as acrylic or polycarbonate. Though these plastics are strong, they can develop hairline cracks and scratches that make it difficult to see through the windows. Replacement windows can be costly and difficult to find for older boats. Build your own boat windows saves the cost of hiring a marine fabricator to do the job.

Things You'll Need

  • Grease pencil
  • Screwdrivers
  • Plastic bags
  • Metal putty knife
  • Tape measure
  • Table router
  • Flush-trim router bit
  • Electric drill
  • Plastic drill bits
  • Caulking
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Instructions

    • 1

      Label the windows. Using a grease pencil, label each window with a number. Write the number in the center of the window. Write the same number above the window’s frame. This allows you to match the windows with their frame. Repeat the process for each window being replaced, using a different number for each window.

    • 2

      Remove the windows. Many marine windows are held in place with screws. Use a screwdriver to remove the mounting screws. Place the screws in a plastic bag. Label each bag with the window’s number recorded in the previous step. Use a metal putty knife to pry the window out gently.

    • 3
      Use a tape measure to determine the window sizes.

      Measure each window, using a tape measure. Allow an extra 1 inch on each side. List the window sizes on a piece of paper. Measure the thickness of each window as well, noting the measurement on the same piece of paper.

    • 4

      Purchase the plastic. Go to a plastics retailer with the list of window measurements. Purchase either acrylic or polycarbonate from the retailer. Purchase material that is the same thickness as the windows. Have the plastics retailer cut each piece to the measurements from in the previous step.

    • 5

      Prepare the plastic for routing. You will route the new windows to shape, using the old windows as routing patterns. Label each piece of plastic with the corresponding window number. Place three long strips of double-sided masking tape on the old window. Center the old window on the plastic being used to replace it. Push down on the old window until the tape is firmly mounted to the plastic. Repeat the process for each window. Leave the protective covering on the plastic.

    • 6

      Route the windows out. Use a flush-trim router bit and a router table. Raise the router bit so its bearing is centered along the edge of the old window. Gently feed the material into the router bit until the bit’s bearing is flush with the old window. Follow the window, which serves as a routing guide, until the plastic is cutout into the window’s correct shape. Turn the router off.

    • 7
      The drill bit must be rated for plastics.

      Drill the screw holes. Use a drill bit rated for drilling through plastic. Use the old window, still adhered to the new window, as a drilling pattern. Place the drill bit into the old window’s mounting holes. Turn the drill on and gently push the bit down until it cuts through the new window.

    • 8

      Mount the windows. Separate the old window from the newly cut plastic and remove the protective layer from the routed plastic. Match each cut window with its corresponding number above the window frames. Apply a thin bead of caulking to the inside of the frame. Place the screws in the drilled holes and tighten them.