International Ultra 300 Antifoul for High Speed Craft 2.5L

Over 40 Knots


International Ultra 300 is our ultimate hard antifouling, providing 1-year protection ideal for powerboats or any streamlined yacht, even in the harshest fouling conditions

Hard antifoulings work by releasing biocide from the surface of the coating to deter fouling organisms. Hard antifoulings don’t really wear, but abrasive material in the water such as silt and sand may lead to a very minor reduction in the film build. Biocide leaching rate reduces over the lifetime of the product. After a few seasons, there may be a residual build-up of product that needs to be removed.

If you have a fast boat, or a fast boat that is used very regularly, then hard antifouling is usually the best product to choose. Boats moored in fresh water normally use these types as eroding antifoulings are designed to erode in salt water and may not erode sufficiently in fresh water. For those who like to race, hard products are a good option as they can be burnished or wet sanded to a smooth finish prior to racing.


  • For use in saltwater, brackish & freshwater
  • Suitable for High Speed Craft
  • Allows scrubbing and polishing for an ultra-smooth finish
  • Premium performance, even in harsh environments.
  • Maintains protection even after hauling
  • Ultra strong formula for high fouling areas
  • 750ml and 2.5 litre size cans


  • Area: Below the waterline
  • Substrates: GRP/FRP, Lead, Steel, Wood, Cast Iron
  • Suitable for high speed craft
  • Suitable for high fouling areas
  • Not suitable for use over Aluminium/Alloy substrates or zinc sprayed surfaces.

Colour Chart



Previously Antifouled Surfaces

In Good Condition: All fouling and contamination must be thoroughly removed including the leached layer. Use high pressure fresh water wash (3000 psi/207 bar) and/or scraping and wet sanding with typically 80-120 grade paper. Do not dry sand. If old antifouling is incompatible or unknown, seal with suitable International Paint barrier/sealer coat. I

In Poor Condition: Use Interstrip to remove all traces of antifouling


  • BARE GRP: Prime with Gelshield 200 for osmosis protection, or Primocon or Interprotect.
  • STEEL/IRON/LEAD/WOOD: Prime with Interprotect or Primocon.


Thinners & Cleaners

Thinning: Thinning is not recommended. Antifouling performance can be compromised if correct dry film thickness is not applied.

Cleaner: International Thinner No.3


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