How to Scrape Barnacles off Fiberglass for Diving

Hardened barnacles are a chore to remove from a fiberglass hull.

A routine check of any fiberglass boat hull is sure to reveal a cluster of barnacles. These shelled sea creatures will attach to any smooth, non-porous surface, including fiberglass and metal. To affix themselves, barnacles emit a glue-like adhesive that creates a strong, lasting bond. With the appropriate tools and a bit of elbow grease, you will be able to rid your fiberglass of barnacles.

Things You'll Need

• Power washer
• Putty knife
• Thick rubber gloves
• Safety goggles
• Acid-based barnacle remover
• Synthetic paintbrush

Instructions

1. Pull the boat from the water and allow the barnacles to dry out. Turn on the power washer. If the washer has adjustable settings, select medium to high pressure for best results.

2. Aim the nozzle at the barnacles and begin spraying them off of the fiberglass. Stand and aim parallel to the fiberglass as you wash to prevent damage to the surface. Continue washing until most of the barnacles have been sprayed off or loosened.

3. Wedge the edge of the putty knife between any remaining barnacle shells and the fiberglass. Scrape to the side or downward to break the adhesive bond. Continue until the remaining barnacles have been removed.

4. Pull on the thick rubber gloves and safety goggles to protect yourself from the acid-based barnacle remover. Barnacle removers are available at marine-supply stores.

5. Dip a synthetic paintbrush into the barnacle remover and spread it over the patches of leftover barnacle adhesive. Allow the adhesive to foam and dissolve before scraping it away with the putty knife. For best results, treat only small areas at a time.

6. Wash the fiberglass with soap and water to remove all traces of the barnacles and barnacle remover.

Tips & Warnings

• Muriatic acid may be used to loosen stubborn barnacles. Use safety goggles, thick gloves and a mask for breathing while spreading the acid over the barnacles. Once it has dissolved the adhesive, wash the area with soap and water to neutralize the acid.

• Do not allow children or pets near the container of acid-based barnacle remover.

• Work in a well-ventilated area, preferably outdoors, to prevent fume inhalation.

References

• Mad Mariner: Removing Those Pesky Barnacles
• Jersey Shore Fishing: Removing Barnacles From Your Boat; Daniel Nee, 2011