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Coatings are usually applied every 3-5 years during dry-docking (Tamburri et al. 2020, 2). However 
different coating types (going further into detail in chapter 2.1.1 and 2.1.2) work differently and 
have varying lifetime spans (BIMCO 2021). Consequently, there is no generally valid definition of 
age of coatings in “new”, “medium” or “old” but once the service life of an AFS is expired, IWC is 
not recommended (BIMCO 2021). 
The amount of paint flakes removed via IWC and therefore the extent to which hazardous 
substances and particles end up in the water does not solely depend on the factors mentioned in 
chapter 1 (age and condition of the coating, hull roughness, maintenance history) but also on, and 
especially in combination with the cleaning method used (type of brush, cleaning machine, 
aggressiveness of the cleaning, etc.), the effectivity of capture and filtration, the competence 
of the cleaning company and the type of coating (Morrisey et al. 2013). For the choice of the 
zoating type, the operational profile of the ship should be considered, including service speed, 
activity level, idle period and traded waters (Watermann et al. 2021). Another aspect which is 
highly important to consider when choosing the AFS is the construction of the ship. Niche areas 
need to be checked on their accessibility and cleanability. By changes in speed, they are exposed 
to different water flows which might lead to the recommendation of choosing a different kind of 
AFS for certain niche areas than for the hull of the ship (MEPC 2011, Watermann et al. 2021). 
Furthermore, legal requirements for the use of AFS must be met (MEPC 2011). There are two 
major types of coatings considered in this paper, the biocidal and the biocide-free ones. 
Biocidal AFS are reckoned to be harmful for the marine environment as they release chemicals 
that might affect the fecundity, mortality and hormonal functions of aquatic organisms (Keep the 
Archipelago Tidy Finland 2020). For this reason, all paints for commercial shipping must be in line 
with the IMO AFS convention. Biocide-free fouling release coatings generate a surface where 
oiofouling hardly can stick to and have therefore a low risk in regard to the release of biocides 
during cleaning activities (Keep the Archipelago Tidy Finland 2020). 
2.1 Type of coatings 
The subcategories of AFS types are defined slightly different in publications. This document refers 
to the classification from New Zealand (Morrisey et al. 2013): 
» Biocidal (going further into detail in chapter 2.1): 
a) Soluble matrix (ablative), 
b) Insoluble matrix (contact leaching/diffusion), 
c) Self-polishing copolymer (SPC) and 
d) Metallic. 
Biocide-free (going further into detail in chapter 2.2): 
e) Fouling release and 
f) Mechanically resistant 
Concerning biocidal coatings, the most commonly used ones are soluble and insoluble matrix 
coatings as well as the self-polishing copolymer (SPC) coatings (Scianni & Georgiades 2019). 
3