Next-Generation Coating: Planning the Dry Dock Choice
Select the external anti-fouling system against AFS compliance, operating profile and planned maintenance. Advertised coating life does not change bottom-survey and docking due dates.
Operational Explanation
Anti-fouling and fouling-release systems have different operating conditions. Compare speed, idle periods, trading areas, surface preparation and warranty with the ship’s actual data. IMO biofouling guidelines are recommendations: check additional requirements of the relevant jurisdiction.
“Next generation” is a commercial description to translate into a verifiable mechanism. Self-polishing systems may release biocides as their film renews; fouling-release systems reduce organism adhesion and help detachment as the ship moves. The latter may be biocidal or non-biocidal: the technology name alone does not establish composition. IMO, MEPC.1/Circ.918, §3.1.
The choice produces an area-specific specification and maintenance plan: expected performance, operating limits, preparation of the existing system, checks and planned repairs. A saving or service-life figure can only be assessed together with the conditions under which it was obtained and the warranty offered.
Regulatory Reference
IMO: AFS Convention; MEPC.378(80), 2023 Biofouling Guidelines. MSC.215(82), the PSPC for dedicated seawater ballast tanks and certain double-side skin spaces, does not govern external anti-fouling. Surveys separately follow applicable statutory and class requirements.
Application or reapplication of cybutryne-containing systems has been prohibited since 1 January 2023. Existing external coatings require removal or sealing at the next scheduled renewal after that date and no later than 60 months after last application, subject to the specific exceptions for platforms, non-international voyages and ships below 400 GT accepted by coastal States. Establish the vessel’s position before planning its docking cycle. IMO — AFS / cybutryne.
For ships subject to AFS certification (at least 400 GT, international voyages, excluding platforms, FSUs and FPSOs), changing or replacing the system requires the associated survey and certificate update. AFS, annex 4.
The AFS survey verifies Convention compliance; it does not certify fouling-control performance or application workmanship. Keep AFS documents, the technical specification and work evidence distinct. IMO, MEPC.358(78), §§1.4 and 4.2–4.3.
Scope of Application
Hull anti-fouling coatings and submerged areas. A biocide-free product still requires suitability, documentation and local-condition checks; do not assume universal IMO product approval.
Procedure / How to Complete It
- Check controlled substances and the ship’s required AFS documents.
- Compare the manufacturer’s specification, operating profile and compatibility with the existing system.
- Agree preparation, application conditions, checks and repairs to damaged areas.
- Assess the hull and niche areas, such as sea chests and tunnels, separately.
- Plan coating-compatible inspection and cleaning permitted locally, retaining survey due dates.
| Decision | Data to compare |
|---|---|
| Suitability for service | Speed and time underway, idle periods, routes and water conditions against the manufacturer’s stated conditions. |
| Retain or convert the system | Condition of the existing coating, required preparation and compatibility between primer, intermediate coats and finish. |
| Dock programme | Work preceding coating, availability of access and materials, environmental conditions, overcoating windows and required time before immersion. |
| Cost over the period considered | Preparation and application, any cleaning/repairs, vessel downtime and documented warranty conditions, as well as paint price. |
Place checks before subsequent stages: prepared surface, products and batches, environmental conditions, film thickness and observed defects. Times and criteria come from the project specification and relevant manufacturer documents. A regional tie-coat data sheet shows, for example, that compatibility and overcoating windows depend on the system and temperature: these values must not be transferred to every product. Hempel, example Nexus II US PDS, pp. 1–4.
Practical Example
A quotation states a ten-year service life. Ask which idle periods, speeds, cleaning and repairs the warranty permits and price intermediate work; the stated life does not authorise skipping a bottom survey.
The same comparison may reveal a planned long idle period after docking: ask how each proposal accommodates that profile and what inspections or cleaning it entails. If conversion requires more preparation or changes the immersion window, include its cost and time in the programme before ordering.
What Typically Goes Wrong
Selecting on price or advertised life alone, ignoring niche areas, or confusing a product data sheet with the ship’s AFS certificate.
The problem becomes apparent when a proposal suited to actual operation requires work incompatible with available time, or when the same criterion is applied to the hull and niches with different flow conditions. The decision must resolve both questions before prices are compared.
Common Mistakes Mistake Library
| Mistake | Consequence | How to Avoid It |
|---|---|---|
| Choose a coating without comparing it with the ship’s actual idle periods and speeds. | The system may operate outside intended conditions, with fouling accumulation and additional maintenance. | Compare operating data, stated limits and required maintenance before accepting the specification. |
| Convert the system without confirming preparation, compatibility and time before immersion. | Adhesion and finish may be defective; repairs and waiting may delay leaving the dock. | Agree the system and checks with the manufacturer and include its stages in the yard programme. |
| Use the same hull solution without assessing sea chests, tunnels and other niches. | Areas with different flow and access may remain inadequately protected or difficult to maintain. | Define a suitable system, access, checks and maintenance for each area. |
| Treat an AFS certificate or advertised life as proof of performance or extended survey intervals. | Work quality and survey due dates may be managed using the wrong document. | Separate AFS compliance, specification/warranty and the statutory and class calendar. |
What the PSCO Checks
Operational Tips
- Compare total cost and warranty conditions.
- Record product, treated areas and application checks.
- Check permits and waste handling before in-water cleaning.
For in-water cleaning, compare the available method, coating type and condition, fouling and areas concerned; establish local permissions and waste handling. IMO’s 2025 guidance addresses this compatibility: “biocide-free” does not make every cleaning harmless or permitted. IMO, MEPC.1/Circ.918, §§4.1 and 6.4.
Preparation checklist
- AFS documents checked
- Operating profile compared
- Preparation and checks defined
- Niche areas considered
- Warranty and maintenance clarified
- Survey due dates retained
- Area-specific specification, compatibility and preparation of the existing system confirmed.
- Overcoating windows, environmental conditions and time before immersion included in the programme.
- Products/batches, film thickness, defects and repairs connected to checks.
- Warranty and inspection/cleaning plan consistent with expected service.
FAQ
Related Topics
Certified substantive revision: 13 October 2026 · page fingerprint da105a855906