Boat Bottom Paint Calculator

Use this boat bottom paint calculator to estimate the amount of paint, cost, and labour needed to keep your vessel's hull protected and looking great. Whether you search for a "bottom paint cost estimator" or a "marine hull coating calculator", this tool provides quick, reliable numbers.

Wetted Surface Area ≈ Hull Factor × LWL × (Beam + Draft)
Gallons Needed = (WSA × Coats) ÷ Coverage per Gallon

Useful Information About Bottom Painting Your Boat

Types of Boat Bottom Paint

  • Ablative (self-polishing) – wears away slowly to expose fresh biocide. Great for boats that sit on a mooring or are trailered regularly. No heavy buildup over time.
  • Hard / modified-epoxy – creates a tough shell that resists scrubbing. Best for high-speed boats or hulls that are cleaned frequently while in the water.
  • Hybrid – combines characteristics of ablative and hard paints. A popular middle-ground for cruisers.
  • Copper-free – uses zinc or other biocides instead of cuprous oxide. Required in some eco-sensitive waterways (e.g., parts of California and Scandinavia).

Surface Preparation Tips

  • Pressure-wash the hull to remove old growth before sanding.
  • Sand with 80-grit paper to create a profile for the new paint to grip.
  • Apply an epoxy barrier coat if the existing paint is incompatible or you are switching paint types.
  • Prep and materials typically add 10–20% to total cost but dramatically extend paint life.

How Often Should You Repaint?

Most ablative paints last 1–2 seasons in warm tropical waters and 2–3 seasons in cooler climates. Hard paints can last longer but may need more coats over time as buildup grows. Freshwater boats generally need repainting less often than saltwater vessels.

Environmental & Legal Considerations

  • Some regions ban copper-based paints — always check local rules before purchasing.
  • Sanding and paint waste must be captured; many boatyards require tarps and vacuum sanders.
  • Eco-friendly alternatives (silicone-based foul-release coatings) are growing in popularity for larger yachts.

Average Cost Ranges (2024–2025)

Budget antifouling paint starts around $100–$150 per gallon, mid-range brands run $180–$280, and premium multi-season paints can cost $300+. Professional application typically adds $15–$40 per linear foot of hull depending on your region and yard.