How to Repair the Fiberglass of a Sailboat Keel

Repairing the fiberglass of a sailboat keel is a crucial aspect of maintaining the structural integrity of the craft. The keel is the backbone or spine of a sailboat and the integrity of the keel determines -- in part -- the worthiness of the boat. Repairing the fiberglass of a sailboat keel requires precision and time, but is not a particularly daunting task.

Things You'll Need

  • Power drill
  • 1/8-inch bit
  • Tape measure
  • Permanent marker
  • Fiberglass resin
  • Resin hardener
  • Fiberglass cloth
  • 1-gallon disposable bowl
  • 4-inch paintbrush
  • Paint mixing stick
  • Sandpaper
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Instructions

  1. Keel and Fiberglass Preparation

    • 1

      Draw semi-circles around the two ends of the keel's crack. If the keel is fractured, circle the end of each crack in the fracture.

    • 2

      Drill holes through the ends of the crack or the ends of each crack in the fracture with the power drill and the 1/8 inch bit. The end of the crack must serve as the radius of the 1/8 inch bit holes to prevent the cracks from lengthening.

    • 3

      Cut two strips of fiberglass cloth 6 inches wide and 1.25 times the length of the crack or four times the diameter of the fracture. Cut a third strip of fiberglass cloth 9 inches wide and 1.5 times the length of the crack or six times the diameter of the fracture.

    • 4

      Mix the fiberglass resin with the resin hardener in the 1-gallon bowl using the paint-stirring stick. Follow the instructions of the resin's container to mix the proper ratio of resin to hardener.

    Fiberglass Application

    • 5

      Tack the edges of one of the smaller pieces of prepared fiberglass cloths over the crack or fracture with the 4-inch paintbrush and resin/hardener mixture. Distribute the diameter of the cloth evenly over the crack or fracture, all sides an equal distance from the crack or fracture. Stretch the cloth tight over the keel, leaving no wrinkles. Allow the tack to dry for 20 minutes.

    • 6

      Apply the resin/hardener to the fiberglass cloth, covering the crack or fracture with light, short strokes. Be careful not to tear the cloth. Saturate the entire cloth.

    • 7

      Apply the second small cloth over the first patch immediately. Allow the resin/hardener to saturate the second cloth. Where the second cloth remains unsaturated, dab the cloth with the resin/hardener mixture. Do not stroke the cloth, dab it. Allow the resin/hardener mixture to dry for 20 minutes or until tacky.

    • 8

      Place the large cloth over the patched area of the keel, distributing its diameter evenly. The cloth should adhere to the tacky resin/hardener mixture. Dab the large cloth, saturating it entirely. Allow the resin/hardener to dry for 24 hours.

    • 9

      Sand the patch lightly, removing all rough edges.