Coating systems for different areas of a ship

Coating systems for different areas of a ship

Marine vessels contain a wide variety of service environments that each require protection from the elements. Many coating systems have been developed to meet the protect every part of a marine vessel, from bow to stern, bridge to hull, and every space in between.

Here, common service environments on ships are examined and coating systems that perform well in those environments are introduced.

Tank coating systems

Ships are full of tanks, each with unique functions. In terms of tank coating systems, one size does not fit all. Consider these different types of tanks:

  • Liquid cargo tanks – The coatings in tanks responsible for carrying crude oil, chemicals, or other liquids must protect the underlying steel from corrosion and must be inert toward the products they contact. Epoxy polyamines, epoxy polyamides, epoxy phenolics, high-build solvent-free urethanes, and inorganic zincs are typically used in these spaces.
  • Freshwater tanks – Coatings in these spaces must protect steel and not impart off-tastes to potable water. In the U.S., potable water tanks must comply with NSF / ANSI Standard 61. Other countries may have different rules. Typically, two- or three-coat epoxy polyamide or epoxy polyamine systems meet these standards.
  • Ballast tanks – These areas feature varying levels of salt water and warm temperatures, making them ideal for corrosion to occur. The Safety of Life at Sea (SOLAS) convention contains provisions on corrosion prevention in seawater ballast tanks. Coal-tar or surface-tolerant epoxy systems are typically used for ballast tank coatings. It’s important to note that these tanks include baffles, so additional stripe coatings with high-build, edge-retentive properties are recommended.

Engine and equipment spaces

Color matters in interior spaces such as engine rooms, work areas, storage spaces, and common areas. Lighter colors help reflect light and improve visibility. Cleanliness is also important in these spaces, so coatings that are easy to clean are recommended.

Bulkheads and overheads are best protected by the following formulations:

  • Epoxy polyamides
  • Surface-tolerant epoxies
  • Long-oil alkyd primers with alkyd undercoats and topcoats

High-temperature spaces require higher-performance coating systems compared to standard coatings. High-build epoxies or inorganic zinc silicate coatings are best used in high-temperature settings.

Interior and exterior decks

Decks are best protected by epoxy polyamides or surface-tolerant epoxies. If deck surfaces will sustain abuse from cargo or equipment, a topcoat of glass fiber-reinforced epoxy is recommended. Interior and exterior surfaces that will see high traffic or moisture should have non-skid additives as part of any coating.


Trade-offs exist when it comes to coating superstructures. Zinc / epoxy / polyurethane systems perform well and are common for new superstructure construction. But they’re relatively hard to repair compared to single-package acrylic or alkyd systems.

On the other hand, acrylic and alkyd systems tend to lose their color after a shorter period, so more frequent re-coats are expected. Polysiloxane topcoat systems have been explored by the U.S. Navy and large cruise and cargo shipping companies, but these systems come with very specific primers and overcoat times.

Underwater hull

While coatings on hulls must protect the underlying steel from corrosion, they must also keep it smooth. That’s because any roughness on the hull creates favorable conditions for the thousands of species of plants and animals in oceans to become attached.

Burdened with these additional passengers, ships weigh more and encounter underwater “drag” similar to what aircraft experience when surfaces aren’t kept smooth.

Antifouling coatings are key to hull protection because they prevent the growth of these organisms. An in-depth look at how antifouling coatings work can be found in this article.

Exterior hull (boot-topping)

The coating used to protect the hull usually is extended upward to the rail; antifouling coatings are not necessary on surfaces that won’t contact the water.

The more important consideration is that a ship’s boot-topping often strikes equipment —sometimes forcefully— during docking and undocking. Additional protection may be warranted for this reason, and an inorganic zinc primer followed by two coats of epoxy perform well in these settings. It’s important to regularly inspect and repair boot-topping to ensure peak performance.