Painting systems are essential to preserving a ship’s structure and components. Unfortunately, they are not a permanent solution. When a ship does not experience obvious damage (e.g., caused by grounding or a fire) or conditions that could compromise a protective coating’s strength (e.g., extreme temperatures), it is important to be mindful of the circumstances that could necessitate repeat surface preparation and coatings to prolong the vessel’s life and ensure crew safety.
Signs a Ship Needs a New Surface Coating
1. Time
Many protective coatings have a lifespan of about four or five years. During the time a ship is in the water, it will likely encounter water temperatures that will cause the hull to flex and contract. Temperature differences can promote the paint’s adhesion to the substrate or cause the substrate to flex, forcing the paint to pull away and rub off with impact.
A damaged surface coating promotes the formation of rust on a substrate, particularly if a vessel is in saltwater. Corrosion increases a ship’s drag, which increase is fuel consumption. By using an appropriate marine coating and replacing it as often as the manufacturer recommends, you will reduce a ship’s surface resistance, increase its speed by up to 20 percent, and increase fuel efficiency by up to 12 percent.
Ships in the water aren’t the only vessels that need new surface coatings. Because of the exposure to the elements, dry docked vessels might need an extra coating if they sit out of the water for over a year.
2. Cavitation
Cavitation is a common type of corrosion-related damage that many ships experience. It occurs when gas bubbles, or vapor cavities, on a metal surface implode because of the forces acting upon the liquid. It usually occurs when water undergoes rapid pressure changes. The cavities form when pressure is low and implode when exposed to higher pressure. The process can generate shock waves and form holes, valleys, grooves or wavy surfaces on a ship.
The turbulence and particle impact created by the phenomena destroys protective coatings, leading to high corrosion rates, even in materials that would otherwise resist corrosion in static conditions. Rudders are often vulnerable to cavitation and are a critical surface to coat according to the U.S. Coast Guard. Cavitation-corrosion on this and other critical-coated surfaces can cause significant financial consequences and losses of operational days, making it crucial to keep maintenance schedules and address cavitation-related damage as soon as possible.
3. Evidence of Coating Failure
Depending on a ship’s environment and surface preparation and coating methods, there are instances in which you should replace (not just retouch) a vessel’s paint system. Signs that a coating failed prematurely include:
- Cratering: The layers of paint make the surface appear dimpled
- Flaking: Patches of paint peeled and left ragged edges
- Blistering: Water becomes trapped under a paint “bubble”; if the water escapes the bubble, it may leave an air pocket within the coating
Surface Preparation and Coatings for Ships
Recoating a ship is a process that includes removing the old paint, cleaning and preparing the substrate, and applying a new protective coating. The Coast Guard recommends the use of marine temporary climate solutions throughout the surface preparation and coating process when ambient conditions may exceed parameters. Temporary climate solutions also help ensure a substrate remains dry and surface temperatures remain 5°F above the dew point temperature.
Marine coatings offer a layer of protection that reduce the need for maintenance and repairs, and extend a vessel’s life. Maximize your investment with Polygon’s custom marine temporary climate solutions. When used with dry-docked ships, the system allows workers to complete maintenance tasks throughout the year. Similarly, if a ship is moored, the climate control solutions keep surfaces that would otherwise be cold because of water temperatures at the appropriate temperature to prevent condensation and high relative humidity levels. Get in touch with Polygon today to learn more about how our custom temporary climate solutions will simplify your surface preparation and coating project.
[Alex Brown via CC License 2.0]
