The steps to apply anti-fouling bottom boat paint are different for brand-new boats, as opposed to older boats needing a recoat, because new boats need the wax used to free them from the mold removed. Harnessing our own experience and expert input from Margo Hunt, support manager at Pettit Marine Paint, we created this boat primer for you. Know that the process for bottom painting a boat is the same regardless of the product brands you choose. The first tip is to wear a respirator as well as protective eyewear, gloves and clothing when performing these tasks.
How to Bottom Paint a Boat
Step 1: Preparation
Dewax with no Volatile Organic Compound (VOC): The mold-release wax must be removed from new hulls. Apply Pettit’s Bio-Blue Hull Surface Prep 92 with a short-nap roller to a 5-by-5-foot area. Scrub with a Scotch-Brite pad, wipe with a wet sponge to remove residue, and rinse the sponge and surface often, changing the rinse water often.CHANGES MADE TO TEXT:
Dewax with VOC: Tried and true solvents, such as Pettit’s Dewaxer D-95, work too. Apply a wet coat in a circular motion liberally and wipe dry with a clean cloth. Change cloths often, lest you reapply the wax you just removed. Clean at least four times to ensure complete wax removal.
Step 2: Sanding
After dewaxing, you need to give the hull some “tooth.” Sand the hull with 80-grit paper until it looks dull and “frosty.” Wipe with 120 Brushing Thinner to remove sanding dust.
Skip Sanding: Pettit’s 6998 Skip Sand Primer eliminates the need to sand because it chemically etches the hull. It’s ideal for use over vinylester gelcoats where sanding may void warranties. The typical street price is $30 to $40 per quart.
Step 3: Insurance
Some fiberglass/resin matrices can absorb water over time — often with disastrous results. Consider applying a barrier coating, such as Pettit Protect 4700/4701, if you wet-store your boat to help avoid the problem. Do this before applying the anti-fouling paint for the fiberglass boat.
Step 4: Bottom Coat
If you applied a barrier coating, apply an anti-fouling coating of your choice while the 4700/4701 is still tacky. If not, apply the anti-fouling coating, following the directions on the can.
For Older or Previously Painted Boats
If your previously painted boat’s surface is in reasonable condition, simply scrape and sand any loose or flaking areas and recoat, following the manufacturer’s directions on the can.