Underdog Boat Bottom Paint

DURABLE SINGLE-SEASON ABLATIVE BOTTOM PAINT

TotalBoat Underdog is an economical antifouling coating for recreational boats. It's tough finish makes Underdog ideal for boats that are trailered or beached regularly throughout the season. 23.7% Copper biocide helps prevent barnacles, slime, algae, and weeds on fiberglass, wood, and primed steel hulls below the waterline in freshwater, saltwater, and brackish waters.

Unlike softer traditional ablative paints, Underdog dries to a tougher finish that better withstands abrasion from hauling or relaunching while still gradually wearing away underway to continuously expose fresh biocide for reliable antifouling protection. Perfect for powerboats and sailboats in light-to-moderate fouling conditions, especially boats used seasonally or stored out of the water between trips.

EASY TO APPLY - EVEN OVER OLD BOTTOM PAINT

Underdog applies smoothly on properly prepared fiberglass, wood, and primed steel hulls using a brush, roller, or spray equipment. A 3/16" nap solvent-safe roller provides even coverage across larger surfaces, while foam or chip brushes work well around waterlines, chines, strakes, and fittings. For larger hulls and commercial applications, Underdog can also be applied using conventional or airless spray equipment.

Depending on application conditions and equipment setup, this bottom paint can be thinned up to 10% using TotalBoat Brushing Thinner 100 or Spray Thinner 101. Ablative formula reduces heavy paint buildup for easier maintenance

Not sure how much boat bottom paint you’ll need? Try our bottom paint coverage calculator to estimate how much you'll need for your project.

FLEXIBLE HAUL AND RELAUNCH SCHEDULES

Underdog dries quickly with no sanding required between coats under normal recoat conditions, helping simplify seasonal bottom painting projects. Depending on temperature and humidity, the coating dries to recoat in as little as 1.5 hours. For best results, apply between 50-90°F with humidity below 90%.

Need flexibility around launch timing? Underdog features no maximum dry time before launch, allowing you to prep and paint ahead of schedule without losing antifouling effectiveness. If your boat sits out of the water for more than 2 weeks, reactivate the biocide with a light scuff-sand before splashing.

UNDERDOG ANTIFOULING PAINT FOR TRAILERED BOATS

• Durable ablative antifouling paint perfect for recreational boats that are trailered, beached, or hauled regularly
• Formulated with 23.7% cuprous oxide to help prevent barnacles, slime, algae, and weeds
• Tougher cured finish withstands trailering and beaching better than many traditional ablative paints
• Wears away gradually underway to continuously expose fresh biocide with less paint buildup over time
• Works on fiberglass, wood, and primed steel hulls below the waterline in saltwater, freshwater, and brackish water
• Compatible with most existing hard and ablative antifouling paints in good condition
• Apply by brush, roller, or spray; thin up to 10% with TotalBoat Brushing Thinner 100 or Spray Thinner 101 if needed
• No sanding required between coats under normal recoat conditions
• No maximum dry time before launch for flexible spring prep and maintenance schedules
• Colors: Choose from Black, Blue, and Red
• Sizes: Available in Gallons
• Gallon Bonus: Each Gallon order includes a paint roller frame, recommended 3/16″ nap solvent-safe roller cover, metal tray, 10" stir stick, XL paint suit, 2" chip brush, a maroon abrasive pad, and a roll of 1" painter’s tape. For additional supplies, we also offer this Bottom Painting Supplies Kit separately.
• Recommended Primer: TotalBoat TotalProtect Epoxy Barrier Coat Primer
• Recommended Brush: Chip Brushes
• Not for use on aluminum hulls - use TotalBoat AlumiPaint AF Aluminum Antifouling Paint or TotalBoat Krypton Copper-Free Bottom Paint on aluminum
• Storage: Store in a cool, dry, well-ventilated area, protect from freezing.