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Paint & Coating Systems

Antifouling Coating

The final coat below the waterline, formulated to release biocide or resist adhesion so marine growth cannot take hold. Its performance decays on a schedule, and that schedule increasingly outlasts a vessel's drydocking interval.

34models
Sherwin-Williams Marine
Knowledge

What to check on an Antifouling Coating.

34 models from Sherwin-Williams Marine in Antifouling Coating. Below: the full model list.

What makes this type

Antifouling coating is the outermost layer of the underwater hull coating system, applied specifically to prevent barnacles, algae and other marine organisms from attaching and growing on the hull. Unlike the anticorrosive coats beneath it, whose job is to keep water off the steel, the antifouling coat's whole purpose is to interact with the water around it, either by releasing a controlled dose of biocide as it wears (self-polishing copolymer, SPC) or by presenting a low-friction silicone surface organisms cannot grip (foul-release). The choice between these two mechanisms shapes everything from application method to expected in-service performance.

Antifouling coating, hull layer build-up
Cross-section through the underwater hull coating system, from the steel plate through primer and anticorrosive to the antifouling topcoat releasing biocide into the surrounding seawater.

Main components

Self-polishing copolymer systems

A binder that erodes slowly in seawater, continuously exposing fresh biocide at the surface and shedding a thin layer of paint over time, which also keeps the hull relatively smooth as it wears.

Biocide-free foul-release systems

Silicone or fluoropolymer coatings that rely on surface energy and elasticity rather than biocide release; organisms that do attach are removed by the shear forces of water flow once the vessel is underway at speed.

Read the full guide

Tie coat

An intermediate coat that bonds the antifouling layer to the anticorrosive system beneath it, particularly important with foul-release systems where adhesion between dissimilar coating chemistries is otherwise poor.

Selection / Sizing

  • Vessel speed and activity profile, since foul-release coatings depend on regular underway speed to stay effective, while SPC systems work at anchor and in port as well.
  • Trading pattern, as vessels with long idle periods in warm, biologically active ports need a formulation matched to that exposure.
  • Intended drydocking interval, since the coating's biocide reserve or surface life must cover the full period between dockings.
  • Compatibility with the existing anticorrosive system and tie coat if the coating is being changed at the next docking.

Regulations / Class

The IMO International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention) bans the use of organotin compounds such as TBT in antifouling systems, a restriction that reshaped the market toward copper-based SPC and biocide-free alternatives. Class societies do not typically approve antifouling products directly, but performance and drydocking planning are reviewed as part of the vessel's hull condition and the owner's biofouling management plan, which some flag states and port states now expect to see documented.

Typical faults

FaultConsequence
Coating applied over an incompatible or poorly prepared tie coatDelamination, patches of bare anticorrosive exposed early
SPC system on a vessel with long idle periods and low speedInsufficient polishing rate, biocide release falls off before drydocking
Foul-release coating on a slow or frequently idle vesselFouling settles and is never sheared off by flow
Under-thickness application at the waterline and boot topPremature fouling exactly where drag has the largest effect on fuel consumption

What to look for in a supplier

  • A documented performance guarantee tied to the vessel's actual speed and idle profile, not a generic drydocking interval.
  • Confirmed compatibility with the coating already on the hull if this is not a full strip to bare steel.
  • Application specification including dry film thickness at the waterline and boot top, the areas most exposed to wear.

Match the coating type to how the ship is actually operated, not how it was designed to operate; a foul-release hull spending months laid up will foul just as badly as an unpainted one.

Models

Models in this type.

The best-documented model of each manufacturer first, then the next — 34 of 34 models in Antifouling Coating. Every row links to full specifications, documents and service notes.

Showing only Sherwin-Williams Marine. Show all manufacturers
34 models
Would you like to know more?

One request. A person reads it and replies by e-mail.

Tell us the manufacturer, the model and what you need — a part, a service call, a second opinion. A person reads every request and replies by e-mail.

No details at hand? A photo of the rating plate or the part is enough — simply attach it to the request.

Frequently asked

Three things people ask first.

Is Antifouling Coating data free?

Yes. Every model page, every guide and every datasheet for this type is readable without an account. An account adds saved searches and requests, nothing is taken away.

My model is missing — what now?

Send us the nameplate. We identify it by hand, add it to the library, and if you need a part or a service, the request is already on our desk.

Can you source a Antifouling Coating part?

Yes. Tell us the manufacturer, the model and what you need — a person reads every request and replies by e-mail.