Hull preservation methods:

• Protective coating systems (paint) consisting of a primer, anti-corrosive (epoxy) coats and an antifouling topcoat, applied to the hull (submerged parts) and the boot-topping; this protects the steel from corrosion and reduces fouling.
• Cathodic protection: sacrificial anodes (zinc/aluminium) and/or impressed current cathodic protection (ICCP) to protect the underwater hull and appendages against galvanic corrosion.
• Regular in-service maintenance: drydocking at the class survey intervals for inspection, cleaning and recoating of the hull; underwater hull cleaning (in water cleaning by divers) and propeller polishing between dockings to remove fouling and improve efficiency.
• Maintaining the paint film and touch-up of damaged areas; keeping anodes effective and monitoring corrosion.
• Keeping the underwater hull clean reduces drag, fuel consumption and GHG; and meets the AFS requirements.

Types of antifouling coats:

• Biocidal/self-polishing antifouling coatings (e.g. TBT-free copper/co-polymer, and tin-free) that slowly release biocide (copper, biocide) to deter fouling organisms;
• Hard/vinyl antifouling (older).
• Biocide-free/fouling-release coatings (silicone/fluoropolymer-based) that have a low surface energy so organisms do not attach strongly and are shed by the vessel's movement/washing;
• Hybrid/controlled depletion polymer (CDP) and SPC (self-polishing copolymer) systems.

Organotin compounds (tributyltin/TBT and its derivatives) used as biocides in antifouling paints were banned by the International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention 2001, in force 2008). Reason: they are extremely toxic and persistent, leach into the marine environment causing the contamination and death of non-target organisms, bio-accumulate in the food chain, and have been linked to endocrine disruption in marine snails (imposex) and damage to mariculture/fisheries. The ban prohibits the presence/application of organotin and requires ships to have a seal coat/remove such paints; the ban also covers other harmful anti-fouling systems of similar effect if adopted.

• Deck coatings: are subjected to heavy mechanical wear, abrasion (foot traffic, cargo handling, fluid spills, dragging of wires/containers), and are often non-slip; they must be thick, tough, resistant to impact, abrasion, chemicals (oil, fuel) and weather; typically an epoxy primer with a tough topcoat or a specialised deck paint (possibly non-skid aggregate) and sometimes a higher-build; they need good flexibility and resistance to severe UV/thermal cycling; on walkways non-slip properties are important.
• Superstructure coatings: are more decorative/architectural; they must resist UV, salt/chloride, and the weather but are not underfoot; they are smoother, lower-build decorative topcoats (often polyurethane or silicone "topcoat") over an epoxy primer for corrosion protection and long colour/gloss retention and ease of cleaning; they are less abrasion-resistant but provide better appearance and gloss and corrosion protection of the external steel and edges.

Additionally both must be compatible with the substrate (steel/galvanising) and maintain weather/water resistance; deck paints are usually more functional/reparability, superstructure paints more aesthetic with a smoother finish.