Yacht Antifouling in Greece – Application & Underwater Hull Protection

Antifouling application and protection of underwater surfaces for yachts and boats, with proper preparation, compatible primers and a coating system selected according to the substrate and scope of work.

Antifouling Services

Technical Yacht Services undertakes surface cleaning and preparation, assessment of the existing coating system, local repairs where needed, application of a suitable primer and antifouling according to the specifications of the selected system. The work may be part of annual maintenance or a wider yacht refit.

Underwater Hulls, Shafts & Different Substrates

The scope is tailored to the actual material and condition of the vessel. For GRP, wood, steel or aluminium, compatible preparation and protection systems are used to achieve proper adhesion and protect underwater surfaces.

Antifouling Technology: Biocides, Substrates and Service Life

Antifouling selection depends on hull material, the existing coating system, vessel usage and the required protection interval.

Primary Biocides and Booster Biocides

Biocidal antifouling paints often contain Cu₂O or CuSCN and, depending on the formulation, booster biocides such as copper pyrithione (CuPT), zinc pyrithione (ZnPT), DCOIT, zineb or tralopyril. Their release depends on the chemistry and structure of the polymer binder, not simply on their concentration. Each active ingredient and finished product is subject to the applicable BPR/PT21 regulatory requirements.

Active-ingredient concentrations vary with the formulation.

Active-ingredient concentration (% by weight) is not equivalent to the release flux into seawater or actual antifouling performance. The kinetics depend on the polymer binder, solubility and operating conditions.

Which Materials and Metals Are Compatible?

Substrate	System Selection
GRP / FRP, wood	A compatible antifouling over the specified epoxy or other approved preparation and primer system, according to the product TDS.
Steel and cast iron	Suitable copper-containing coatings can be applied over a continuous, properly specified anticorrosive epoxy barrier. Primer integrity is essential.
Aluminium and aluminium alloys	Avoid metallic copper and Cu₂O coatings because of the risk of galvanic corrosion. Use approved copper-free systems, or specific CuSCN formulations only where expressly permitted by the manufacturer, together with the required insulating system.
Bronze, stainless steel, propellers and shafts	Select a specialist coating for the particular alloy, water flow, adhesion requirements and galvanic protection system. Sacrificial anodes must not be painted.

Compatibility depends on more than biocide chemistry. A complete approved coating specification is required, covering surface preparation, primer, tie coat and antifouling, together with checks of electrical isolation, galvanic couples and cathodic protection.

Service Life and Dry Film Thickness (DFT)

In self-polishing antifouling paints (SPC), the polymer binder gradually hydrolyses and dissolves, while vessel movement also affects coating erosion. Dissolution continues while the vessel is stationary.

Booster biocides such as copper pyrithione (CuPT) and zinc pyrithione (ZnPT) may also be released faster than the coating erodes. Actual service life therefore depends on both the remaining dry film thickness (DFT) and the amount and release of active ingredients.*

Temperature, vessel speed and mooring conditions affect each mechanism differently. Application thickness and expected service life must always be checked against the product technical data sheet.

* In simplified terms, the time until the paint layer is consumed is estimated as t ≈ (initial DFT − minimum DFT) / (dissolution rate + erosion rate). Active-ingredient loss is estimated separately from dissolution and release, as well as from material removed with the coating. Polymer-binder dissolution, coating erosion and each active ingredient's dissolution/release follow different temperature dependencies (Arrhenius relationship) and must be established by testing the particular coating system. Adding the two film-loss rates is a practical approximation.

How Marine Fouling Begins

Within minutes of immersion, a very thin organic layer (conditioning film) forms on the surface from proteins, glycoproteins, polysaccharides and other seawater constituents. A microbial film (biofilm) then develops, influencing the attachment of bacteria, diatoms and algal spores such as those of Ulva. Larger organisms may subsequently colonise the surface, including cirripedes (barnacles), mussels, oysters, bryozoans and tube worms.

Fouling-Release Coatings (FRC)

In silicone FRC systems, low surface energy and low elastic modulus allow the coating to deform, facilitating organism detachment under hydrodynamic shear forces while underway. The degree of network formation and polymer architecture (for example, linear, brush or star) influence elasticity and mechanical strength. Greater flexibility can come with increased susceptibility to abrasion and tearing.

Marine organisms do not all respond alike: some preferentially attach to hydrophobic surfaces, while others prefer hydrophilicsurfaces. Even PDMS can be colonised by cirripedes (barnacles). Amphiphilic and hydrogel-modified systems have been developed to combine hydrophilic and hydrophobic domains, while mechanical strength remains an important design consideration.

For propellers in particular, a critical failure mode is silicone delamination from the primer. In some systems using a PVB etch primer or an intermediate epoxy/silicone coating, adhesion is assisted by aminosilanes or epoxysilanes and depends on chemical bonding and the ability to penetrate the primer before it gels. Inconsistent gel time in an open shipyard can leave areas of inadequate adhesion, which can initiate coating separation (delamination). Barnacles may also settle in vulnerable areas of the soft silicone and reach the primer, aggravating delamination. When the soft coating detaches locally, it does not necessarily leave a rigid protrusion on the propeller. However, the hydrodynamic consequences depend on the extent of failure and fouling.

Biocidal antifouling products placed on the EU market must meet the applicable approval or authorisation requirements under BPR/PT21. Non-biocidal fouling-release coatings do not follow the same biocidal-product authorisation procedure.

Service-life estimates must be based on measured coating-consumption rates for the specific antifouling and the manufacturer's specifications.

Antifouling FAQs

When should antifouling be reapplied?

Frequency depends on the antifouling coating, vessel use, berthing conditions and the existing surface condition. Inspection during haul-out helps define the appropriate scope of work.

Does all the old antifouling need to be removed?

Not always. Adhesion, compatibility of existing layers and any damage are assessed. Depending on the findings, local preparation or more extensive removal of the old coating may be required.

How are submerged metal components treated?

Shafts and other metal components are assessed separately because they do not necessarily use the same coating system as the hull. Preparation and compatible coatings are selected for the specific material.