How to Bottomkote the Hull of a Boat

If you keep your boat in the water for longer periods, bottom paint—also called antifouling paint—is a must. It helps prevent algae, barnacles, and other marine growth from clinging to the hull, reducing drag and protecting your investment.

Here’s how to apply bottomkote the right way.

What You’ll Need:

• Antifouling paint (hard or ablative, depending on use)
• Marine primer (if required)
• Sandpaper or scuff pads
• Paint roller with solvent-resistant sleeve
• Brushes (for edges and tight areas)
• Painter’s tape and drop cloths
• Protective gear (gloves, mask, goggles)
• Jack stands or cradle (if trailer isn’t accessible)
• Stir sticks and mixing bucket

Step 1:

Choose the Right Bottomkote

• Ablative bottom paint wears away gradually and is self-cleaning—great for boats that are used often.
• Hard bottom paint stays intact and resists heavy wear—ideal for faster boats or those frequently trailered.

Bring in your boat specs, local water conditions (fresh vs. salt), and storage habits—Autohome can help you choose the right type.

Step 2:

Haul and Support the Boat

The hull needs to be completely out of the water and securely supported. Use a proper trailer, boat cradle, or jack stands—safety first.

Step 3:

Prep the Hull

Start by pressure washing the hull to remove slime and buildup. Once dry, sand or scuff the bottom using 80–120 grit sandpaper or a scuff pad to help the new paint adhere.

If you’re painting over an existing antifouling paint, make sure it’s compatible with your new product. If it’s not, or if you’re switching types, a barrier primer may be required.

Wipe the surface clean with a solvent wipe or acetone and then a tack cloth.

Step 4:

Tape Off and Mix

Use painter’s tape to mark the waterline for a clean edge. Stir your bottom paint thoroughly—marine paints can separate quickly.

Step 5:

Apply the Paint

Using a roller or brush, apply the paint in smooth, even coats. Focus on coverage, especially around keels, chines, and through-hull fittings. Allow drying time between coats as recommended on the label.

Most bottom paints require two coats for full protection. Some also require launching within a specific window (e.g., within 72 hours of application)—check the label carefully.

Step 6:

Touch Up Support Points

Once the boat is repositioned or off the jack stands, touch up the small unpainted areas.

Protect Your Hull—and Your Performance

A clean, coated hull cuts through water more efficiently and helps prevent long-term damage from marine growth.

Ask Autohome About the Right Bottom Paint

We stock top-performing antifouling paints, barrier primers, and prep tools—and we know what works best for Northwestern Ontario’s freshwater conditions. Bring in your boat details and we’ll walk you through everything you need.