Answer
1. Compliance with AFS convention
2. Period of drydock
3. Paint maker's input on time period for which paint will last, AHR increase
4. Approximate cost of the paint
5. Surface preparation requirement and cost
6. Expertise time required for application
Vessel Operating Profile & Trading Pattern
Speed and Activity Levels: Modern high-performance coatings rely on water friction to work effectively. Premium Self-Polishing Copolymers (SPC) or Silicone-based Foul Release Coatings (FRC) typically require a threshold speed (often greater than 10–12 knots) and high operational activity to continuously shed fouling or polish down smoothly. If your vessel has an operational profile with low speeds or frequent, prolonged periods at anchorage (e.g., certain bulk carriers or tankers), you need an AF system with specialized static-fouling resistance or higher biocide leaching rates tailored for static conditions.
Geographical Trading Areas: If the vessel operates heavily in tropical zones (e.g., the Indian Ocean, Singapore, or the Caribbean), it faces extreme bio-fouling pressure due to warm water temperatures accelerating marine growth. This demands a robust coating with targeted co-biocides or an ultra-slick silicone hydrogel barrier.
International Environmental Regulations
IMO AFS Convention: The paint must be completely Tributyltin (TBT)-free. Furthermore, it must strictly comply with the amendments banning Cybutryne (effective January 1, 2023). If the existing hull contains older cybutryne layers, your choice must incorporate either complete grit blasting to bare steel or the application of a certified sealer/tie-coat.
EEXI and CII Compliance: Frictional resistance from macro-fouling can increase fuel consumption and emissions by up to 20–30%. Choosing an ultra-smooth coating directly optimizes your Shipboard Energy Efficiency Management Plan (SEEMP) and directly prevents a degradation of the ship's annual CII grading.