MARINE3 min read

Marine Coating Trials on Port and Starboard: Balance Exposure before Comparing Products

Avoid confounding coating performance with a boat's mooring and exposure by placing comparable treatment areas on both port and starboard.

Updated · NANOLAB Knowledge

Illustration of a white yacht hull with water droplets and a clean fender at a marina
Editorial illustration

Putting coating A on the port side and coating B on starboard seems convenient. It can also make product and exposure impossible to separate. A vessel may spend long periods with one side facing a dock, prevailing spray or stronger sunlight. Better planning preserves the practical advantages of an onboard trial without relying on a single left-versus-right comparison.

Map the vessel’s normal use

Record the usual mooring orientation, operating pattern, shading, fender contact and cleaning access. Identify differences in surface material and condition. A painted section should not be treated as interchangeable with a differently aged gelcoat section simply because they sit opposite each other.

Keep the project within the supported cosmetic application scope. This plan does not authorise application to submerged areas, walking surfaces, safety equipment or other excluded zones.

Put each candidate in more than one exposure position

Where suitable, create comparable approved test areas for both candidates on each side. Assign positions before application and balance the layout so one candidate is not always nearer a runoff source or frequently handled fitting. Randomise the local order where practical.

Exposure group Illustrative allocation
Port, comparable upper cosmetic areas Both A and B in recorded positions
Starboard, comparable upper cosmetic areas Both A and B in recorded positions
Reference condition A suitable documented control where the project permits it

This is an application of balanced comparison and blocking concepts, not a complete statistical protocol. NIST’s design guidance is useful background when planning a formal study.

Keep maintenance traceable

Record the product, applicator, preparation and cure conditions for each area. Use the agreed care routine and log deviations. If one side is washed more frequently because it is easier to reach from the dock, that difference belongs in the trial record.

Record changes in berth or vessel use. A mooring change halfway through the pilot may alter the exposure pattern and can explain a trend that would otherwise be attributed to product age.

Compare within the exposure groups first

In an illustrative outcome, both candidates remain cleaner on the sheltered side while both collect more residue on the exposed side. A simple port-versus-starboard allocation would have risked declaring the sheltered-side product the winner. Having both candidates in both positions makes the exposure pattern visible.

If A performs differently from B within each group, investigate whether the difference is consistent across independent areas and visits. Repeated photographs of the same patch are useful follow-up records but do not create independent vessels.

Report the vessel-level limits

State the number of vessels, areas, observation periods and relevant deviations. Describe what the pilot supports on the tested surfaces and what further exposure is needed. A disciplined onboard trial can guide product selection and maintenance planning while avoiding a durability claim based mainly on which side faced the dock.

Technical references

These sources support the identified technical concepts. The planning examples in this guide are illustrative and are not NANOLAB performance test results.

Discuss your surface and intended use with NANOLAB. Follow the current instructions for the exact product when planning application and care.