Eco-Friendly Silicone Foul-Release Coatings: The New Era in Hull Protection for Commercial Vessels & Yachts

Zero Biocides • Fuel Savings • Speed • Hydrodynamic Efficiency • 5–10 Years Service Life

Introduction: Why Foul-Release Technology Is Transforming Shipping & Yachting

Hull condition is one of the most critical factors affecting the operational performance of any commercial vessel or yacht.

It directly influences:

• fuel consumption
• vessel speed and hydrodynamic resistance
• CII / EEXI rating
• performance in demanding trades
• dry-docking frequency
• environmental footprint
• the commercial value of the vessel

Traditional antifouling coatings have limited service life and rely on copper/biocides.

Silicone Foul-Release Coating (FRC) technology offers:

• zero-biocide performance
• improved speed
• consistently low drag
• measurable fuel savings
• 5–10 years lifetime

Detailed Description of Silicone Foul-Release Coating

Silicone Foul-Release Coatings (FRC) represent the most advanced and environmentally safe hull-protection technology available today for both commercial vessels and yachts.
They do not rely on biocides but on physical, non-toxic mechanisms that prevent marine growth from adhering.

1. Composition & Material Structure

A typical silicone FRC system is formulated with:

• Polysiloxane (silicone elastomers)
• Fluoropolymers to achieve ultra-low surface free energy
• Specialized elastomeric binders with low modulus
• Hydrophobic and slippery additives that drastically reduce adhesion strength

The result is a smooth, elastic, hydrophobic membrane on the hull.

2. Operating Mechanism

The foul-release coating:

• exhibits extremely low surface free energy
• maintains a soft, flexible surface (low modulus)
• prevents organisms from anchoring deeply
• self-cleans when the vessel is underway (hydrodynamic release)
• performs even at low speeds (from approx. 6–9 knots)

Advanced formulations feature a hydrogel-effect, creating a thin “water-like” layer.

Marine organisms perceive the surface as water and therefore do not attempt to attach.

3. Zero Biocides – Zero Copper

FRC systems release:

• no copper
• no organotin
• no biocides
• no toxic components into the marine environment

This makes them ideal for marinas, ports, environmentally sensitive zones, and all vessels with strict ESG requirements.

4. Hydrodynamic Performance

Silicone FRC provides:

• hull roughness of 50–80 μm
• <1–1.5% speed loss over 5–10 years
• 3–6% fuel savings depending on trade/operation
• higher achievable speed for vessels and yachts
• consistently stable performance throughout the lifecycle

5. Hull Material Compatibility

FRC is suitable for:

• Steel hulls
• Aluminium hulls
• GRP/fiberglass yachts
• Wooden hulls (with correct priming)

6. Idle Performance (4–8 Months Off-Service)

• only light fouling develops
• no deep anchoring
• easy removal via diving cleaning
• no impact on coating lifetime

Perfect for vessels/yachts with seasonal or low-activity operation.

7. Durability & Spot Repairs

The system offers 5–10 years longevity with localized repair possibilities.

Typical wear areas:

• bow area due to anchor & chain contact
• tug-mark zones
• keel abrasion from debris
• fender wear
• waterline scuffing

Repairs are handled through:

• light sanding
• primer → tie-coat → topcoat application

Technical Specifications (TDS-Level Details)

• Total DFT: 250–350 μm
• Topcoat: 150–200 μm
• Primer + Tie-coat: 100–125 μm
• Volume solids: 70–75%
• VOC: 200–250 g/L

Curing:

• Touch dry: 3–6 hours
• Overcoating interval: 6–18 hours
• Immersion cure: 24–48 hours

Performance:

• Speed loss: <1–1.5%
• Fuel savings: 3–6%
• Lifetime: 5–10 years

Application Procedure (Commercial Vessels & Yachts)

Application is performed exclusively by approved applicators and includes:

• certified technician from the coating manufacturer
• vessel superintendent / yacht (technical) manager
• classification society surveyor (where required)

Step-by-step:

1. Abrasive blasting Sa 2½ (profile 50–75 μm)
2. Application of epoxy high-solids primer
3. Application of FRC tie-coat
4. Application of silicone/fluoropolymer topcoat
5. DFT / adhesion / holiday testing
6. Launch and self-smoothing activation during the first miles

Comparison Table: Antifouling vs Silicone FRC

Foul-Release Coating Is Also Applied to Shafts, Rudders & Stabilizer Fins

Fouling does not only affect the hull and propeller.
Equally critical underwater components include:

• propeller shafts,
• rudders,
• stabilizer fins.

These components:

• are permanently submerged,
• directly affect propulsion,
• operate under high hydrodynamic loads,
• and influence fuel efficiency and vessel stability.

1. Shafts (Propeller Shafts)

Shafts are vulnerable to:

• barnacle settlement,
• algae,
• slime growth,
• micro-organisms entering the shaft–stern tube clearance.

Why it matters:

• Fouling increases resistance to shaft rotation.
• Creates micro-vibrations in the stern tube.
• Adds load to bearings.
• May cause long-term alignment deviations.

With foul-release:

• fouling cannot anchor,
• water flow becomes smoother,
• bearing loads decrease,
• shafting system lifespan increases.

2. Rudders

Rudders experience:

• complex geometry,
• heavy hydrodynamic flow,
• continuous angle changes,
• localized turbulence and vortex zones.

Fouling on rudders:

• increases drag,
• reduces steering response,
• triggers cavitation clusters,
• generates noise and vibration.

Foul-release benefits:

• reduced drag,
• improved rudder response,
• lower cavitation risk,
• extended life of rudder stock & bearings.

3. Stabilizer Fins

Stabilizer fins behave like high-load hydrofoils with:

• fast water flow,
• constant angle variation,
• heavy loads during corrections.

Fouling creates:

• higher hydrodynamic resistance,
• reduced stabilizing efficiency,
• increased actuator & hydraulic load.

With foul-release:

• smooth surface maintained,
• lower force required for fin actuation,
• improved stabilizing efficiency,
• reduced hydraulic power consumption,
• extended actuator lifespan.

Overall Benefit of Applying FRC to Shafts, Rudders & Stabilizers

Hull + Propeller + Shafts + Rudders + Stabilizer Fins = Maximum Hydrodynamic Efficiency

A complete underwater foul-release system provides:

• up to 12% total fuel savings
• improved CII / EEXI rating
• lower underwater resistance
• reduced cavitation
• smoother shafting operation
• quicker rudder response
• improved vessel stability
• minimal diving cleaning requirements

Client Questions & Detailed Answers

1. Is it suitable for my commercial vessel?

Yes — particularly for:

• bulk carriers
• tankers
• ferries / ro-pax
• container vessels
• cruise ships
• workboats & tugboats

It improves fuel efficiency, reduces hydrodynamic drag, and stabilizes CII/EEXI performance.

2. Is it suitable for my yacht?

Absolutely. It provides:

• premium appearance
• enhanced gelcoat/aluminium protection
• lower fuel consumption
• higher achievable speed
• extremely low maintenance requirements

3. What happens after 6 months idle?

Only light fouling develops, which the diving team removes easily without harming the coating. Performance remains stable.

4. How long does it last?

5–10 years, with localized repair capability during each dry-dock.

5. Which areas typically show damage?

• bow (anchor & chain contact)
• sides (tug marks)
• keel
• fenders
• waterline scuffing

All areas are repairable with controlled spot application.

Case Study 1: Bulk Carrier 75,000 DWT

• Annual fuel consumption: 8,400 t
• 5% saving = 420 t
• Fuel cost ~650 €/t → 273,000 € annual saving
• Payback period: 2–4 months

Case Study 2: Yacht 24 m

• Annual consumption: 44,000 L
• 3–6% saving → 2,244–4,488 €
• +0.5–1.2 knots speed gain
• minimal maintenance
• premium finish

Final Conclusion

Silicone Foul-Release Coatings deliver:

• superior hull protection
• long service life
• low hydrodynamic drag
• measurable fuel savings
• zero marine pollution
• reduced dry-docking requirements

They are the optimal solution for:

• commercial vessels
• yachts of any size
• professional day-cruise vessels