DIY: Repainting Fiberglass Boats

Updated April 17, 2017

All fibreglass boats have gel coat and pigments that can last from seven to 10 years before fading, peeling, marring and oxidation set in. Fibreglass can be repainted, although it requires special products, painting techniques and thorough preparation. They say that painting any boat involves 90 per cent preparation, and if the prep work has not been performed right, even the costliest of paints and applicators will be ineffective. Since boat hulls can be very large, an assistant becomes a wise investment when performing the work. Only the best two-part marine grade polyurethane paints should be used for fibreglass painting.

Trailer the boat and transport it to a convenient work location. Unhitch the tow vehicle and chock the wheels of the boat trailer. For an effective paint job to adhere, you need to paint the boat when the temperature ranges between 18.3 and 26.7 degrees Celsius. The humidity should be less than 65 per cent. Use screwdrivers or a wrench to remove all the hardware on the boat hull, such as through-hull fitting flanges, cleats, rub rails, the bow eye hook and the fresh water inlet screen, if so equipped.

Mask off any part of the boat that will not be painted. Use masking tape and sheets of plastic to cover the outdrive. Tape the rails down, and cover the deck area fore and aft with sheets of plastic. Tape everything securely. Mix up a batch of wax remover in a large coffee can. Don plastic gloves. Use a rag soaked in wax remover to clean the entire hull, using circular motions. Rub hard into the gel coat surface.

Have an assistant help you by splitting the hull cleaning chore in half. Change out the rags frequently, since they will become loaded with wax and film. Clean all exposed hull. Place a sponge sanding pad on the chuck of an orbital grinder. Place an 80-grit sanding disk on the sponge pad and tighten the disk with a socket. Turn the orbital sander, and begin working at the transom. Sand the entire transom, using medium to heavy pressure.

Move down one side of the hull, and sand from the top rail to the keel. Sand the other side of the hull in the same fashion. Let the sponge pad naturally follow the contours of the curves and raised seams, allowing no undue pressure on the sharper corners and chines. When finished, go over the hull with rags and wax remover, removing all the residue and sanding dust. Change out the sanding disk when it loads up.

Change the orbital sanding disk to the 400-grit disk. Sand the entire hull again. Clean the hull again with the wax remover and rags. Always change the rags out. Look for any imperfections in the gel coat surface, and resand and wipe with wax remover.

Open the fibreglass primer paint and mix it according to the manufacturer's directions. Fill a rolling pan with primer paint and dip the roller in it. Begin painting the transom, using up-and-down strokes in combination with side-to-side strokes. Paint large sections at a time. Overlap previous sections by a few inches.

Allow the primer paint to dry for 24 hours. Inspect the paint surface the next day. Use some pieces of 400-grit sandpaper to hand-sand any rough spots. Mix a two-part marine polyurethane paint into a rolling pan. Use a sponge roller to paint large sections of the hull, starting with the transom. Have an assistant follow your previous painted sections, smoothing out the wet paint with a sponge brush. Work in tandem like this until you circle the boat.

Wait the specified amount of time for the paint to dry, according to directions. Apply a second coat of polyurethane paint to the hull. Again, work in tandem with an assistant. Remove all masking tape and plastic sheets. Use screwdrivers or a wrench to reinstall all of the hardware you removed. Let the paint thoroughly dry, according to directions, before you immerse the boat in water.


After the initial paint job, unhook the bow eye if the boat is lashed to the trailer. Use wood blocks and a floor jack to lift the hull up high enough to paint the spots missed under the support rails and keel rollers. Use the same preparation technique on the missed spots that you used on the rest of the hull.

Things You'll Need

  • Boat trailer
  • Wheel chocks
  • Socket set
  • Ratchet wrench
  • Screwdrivers
  • Masking tape (plumber's blue)
  • Plastic sheets
  • Coffee can
  • Plastic gloves
  • Wax remover
  • Rags
  • Orbital sander
  • Sanding sponge pad
  • Sanding disks (80 and 400-grit)
  • Primer paint
  • Paint rollers (sponge type)
  • Paint roller pan
  • Sponge paint brush
  • Polyurethane fibreglass paint (two-part, marine grade)
  • Wood blocks
  • Floor jack
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About the Author

Chris Stevenson has been writing since 1988. His automotive vocation has spanned more than 35 years and he authored the auto repair manual "Auto Repair Shams and Scams" in 1990. Stevenson holds a P.D.S Toyota certificate, ASE brake certification, Clean Air Act certification and a California smog license.