Why Choosing the Right Hull Colour Has Never Been More Important

It is increasingly recognised that dark hulls absorb more heat, leading to higher interior temperatures and elevated energy expenses. What should you consider when selecting your hull colours?

The final hull colour of a newly built yacht is more than just a finishing touch, it represents thousands of meticulously crafted hours that go into its creation. A dark hull undeniably commands attention, making a bold statement on the water. However, beyond aesthetics, this choice plays a crucial role in the vessels environmental footprint.

The Science Behind It

The external surfaces of a vessel have the potential to absorb infrared radiation (IR) from the sun, depending on factors such as vessel type, substrate, undercoat, and coating. When solar energy strikes a surface, it is absorbed, converted into heat, and transferred to the substrate through thermal conduction. This process can lead to a rise in hull temperatures and, consequently, an increase in the internal temperature of the vessel.

Darker hull colours, such as blue or black, absorb significantly more radiation than lighter shades. As a result, vessels with dark hulls can experience much higher surface temperatures when exposed to direct sunlight, creating substantial temperature variations between dark and light-coloured surfaces. This heightened heat absorption also raises interior temperatures, placing additional demand on air conditioning systems to maintain comfortable conditions. The increased strain on cooling systems leads to higher fuel consumption, ultimately affecting the vessel’s overall energy efficiency. For instance, the difference in interior temperature between a white-painted hull and a black-painted hull can exceed 20°C (36°F).

Low Solar Absorption Paint

If a dark-coloured hull is preferred but concerns about high heat absorption arise, low solar absorption (LSA) coatings offers a practical solution. These specialised coatings are designed to reduce the amount of solar energy absorbed by the surface, helping to mitigate heat buildup. LSA coatings are not only applied to hulls but are also commonly used on hardtops, painted decks, cabin roofs, and even tenders.

The advantages of using LSA coatings include lowering the workload and operational costs of air conditioning systems, creating a more comfortable working environment for the crew, and protecting sensitive electronic equipment from excessive heat. However, for these coatings to function effectively, it is essential to apply a white primer underneath.

Other Considerations

Another key factor to consider when selecting a vessel’s colour is that darker shades are more prone to visible scratches and fading if not properly maintained. This can affect the longevity of the coating, the time between dry docking, and increase the need for resources such as spray materials, energy, and other indirect costs. Additionally, darker coatings may soften slightly when exposed to direct sunlight, making fender damage more noticeable over time. To mitigate these effects, consider advanced coating technologies that incorporate resins designed for enhanced scratch resistance and polishable properties, allowing for in-service restoration of minor damage. Another effective solution is a base coat and clear coat system, as clear coats are easier to buff, polish, and restore when necessary.

When choosing a hull colour, there is no universal solution. Factors such as environment, owner preferences, and vessel usage all play a role in the decision-making process. By considering these insights, you can make a more informed and functional choice in collaboration with your designer or manufacturer.

Source: Water Revolution Foundation, AkzoNobel

Cover Image: Lasai, Tipsy Nomads