Blog 12:
If Propeller Is Painted, Will It Improve Fuel Efficiency?
References:
IMO MARPOL Annex VI, Regulation 28 (CII), MEPC.1/Circ.815 (Energy Efficiency Measures).
IACS Recommendations on Propeller Efficiency, ABS Guide for Propeller Performance.
DG Shipping M.S. Notice 12 of 2021 (Decarbonization Measures).
Painting a propeller with anti-fouling or low-friction coatings can improve fuel efficiency by reducing drag and cavitation, aligning with MARPOL Annex VI, Regulation 28 (CII) goals. Classification societies, such as ABS, evaluate propeller performance, and DG Shipping’s M.S. Notice 12 of 2021 promotes energy efficiency measures for Indian-flagged vessels.
Impact of Propeller Painting on Fuel Efficiency
Mechanism of Improvement:
Reduced Fouling: Anti-fouling coatings (e.g., biocide-free silicon-based paints) prevent marine growth (e.g., barnacles), reducing surface roughness, as per MEPC.1/Circ.815, Paragraph 3.3. Fouling increases drag by 5–10%, per ABS Guide.
Lower Friction: Low-friction coatings (e.g., fluoropolymer-based) reduce hydrodynamic drag, improving thrust efficiency by 2–4%, as per IACS recommendations.
Cavitation Reduction: Smoother surfaces minimize cavitation, reducing energy losses, as per MEPC.1/Circ.815, Paragraph 3.2.
Fuel Efficiency Gains:
A clean, painted propeller can save 3–5% in fuel consumption, as per ABS studies, directly improving CII ratings, as per MARPOL Annex VI, Regulation 28.
Example: A 10,000 DWT vessel consuming 20 tonnes/day saves 0.6–1 tonne/day, reducing CO2 emissions by 1.8–3 tonnes/day (emission factor 3.114 gCO2/g fuel).
Coating Types and Considerations:
Anti-Fouling: Biocide-free coatings comply with IMO’s AFS Convention (2001), as per DG Shipping’s M.S. Notice 12 of 2021.
Low-Friction: Silicon or fluoropolymer coatings reduce drag but require careful application to avoid peeling, as per ABS Guide.
Durability: Coatings last 2–3 years, needing reapplication during dry-docking, as per IACS recommendations.
Limitations and Challenges:
Initial Cost: Painting costs $10,000–$20,000 per propeller, as per industry estimates, but savings offset this over time.
Maintenance: Coatings degrade if not cleaned regularly, reducing efficiency, as per MEPC.1/Circ.815.
Environmental Impact: Some coatings may release microplastics, requiring eco-friendly options, as per DG Shipping’s M.S. Notice 12 of 2021.
Complementary Measures:
Combine painting with PBCF (as you’ve asked previously) for additive efficiency gains (up to 7% total), as per ABS Guide.
Regular polishing during dry-docking enhances coating effectiveness, as per IACS recommendations.
Chief Engineer’s Responsibilities:
Recommend propeller painting during dry-docking, selecting IMO-compliant coatings, as per MARPOL Annex VI, Regulation 28.
Monitor fuel consumption pre- and post-painting, logging data for CII reporting, as per DG Shipping’s M.S. Notice 12 of 2021.
Coordinate with ABS for propeller surveys, ensuring coating integrity, as per IACS guidelines.
Train crew on propeller maintenance, as per STCW Regulation A-III/2.