Deck coatings may be at the unglamorous end of marine coatings, but they are a vital safety feature: pitching and rolling decks, usually wet, and the operation of heavy equipment combine to make special demands. At the same time spillage and abrasion require durable protection.
When it comes to deck coatings, owners and operators always ask for increased longevity, while non-slip effectiveness in specialist markets such as the passenger and cruise sector has always been in high demand.
“Generally, coatings for marine main deck areas will be similar to those used on the superstructure, topsides and hatch covers and often this involves an epoxy primer which is subsequently over-coated with one or more coats,” says Simon Daly, Oil & Gas Segment Manager, Hempel A/S. “In many cases this will involve a top-coat which is used to convey the owners’ corporate image or specific coloured safety markings. There are exceptions for specialist areas, such as for dedicated walkways or flight deck coatings, where additional frictional requirements may be needed.”
He continues: “The oil & gas sector is more challenging as walkways represent a larger percentage of the deck areas and are in constant use, and coatings must protect against weather, impact and abrasion. Additionally, resistance to splashes from chemicals may also be required. Laydown areas for the loading and unloading of containers and other heavy equipment can be particularly challenging.”
Sand and tar
A mix of sand and epoxy tar to provide anti-slip characteristics was the norm until the early 1930’s, when a formulation for mixing natural rubber and cement was developed as a sloping compound and underlayment for ocean going vessels. This was replaced with synthetic rubber polymers when the Second World War made natural rubber scarce, and polymer modified concrete was used on both the interior and exterior of ships such as the Queen Mary, the SS America and the Queen Elizabeth, as well as being adopted by navies. Adding aggregate to the top coat makes them non-slip, but demands from niche sectors are producing new technologies such as resins to fulfil them.
Specialist sectors include cruise ships where aesthetics and comfort are important, and aircraft carrier flight decks where anti-skid paint also has to also resist hot exhausts. For the bulk of the market, however, longevity, ease of application and maintenance are important considerations. In drydock or in port the decks are usually being walked on for loading/unloading and machinery maintenance, so coating repairs are often completed at sea by non-specialists.
Longevity
“Onboard repair coatings must be easy to apply by brush or roller and give the necessary protection and finish,” explains Daly.
“Versatility in repair coatings is also important. Coatings such as our Hempadur OBM 47150 have been developed specifically for onboard maintenance and deliver universal protection. It is an all-round ‘direct-to-metal’ primer and topcoat in one that can be applied by roller or brush to topsides, decks, boot tops, superstructure, hatch covers and cargo holds. A ‘one-coating-fits-all’ solution will also reduce wastage. “
Oil and Gas
Non-slip is now mandatory for specialist areas such as walkways in the oil & gas sector. The challenges in developing coatings for the offshore oil and gas sector are three-fold, says Daly: “First, the sector has far more rigorous anti-corrosion standards that need to be met (such as NORSOK M-501). Secondly, there are specific challenges relating to abrasion, impact and mechanical damage not present in other sectors. Finally, the systems must offer certain additional health and safety properties such as their non-slip and non-sparking capabilities.
“Very often formulating coatings for such environments is a fine balancing act between making the coatings sufficiently resistant to mechanical damage whilst also maintaining the need for flexibility, particularly on large deck areas or those exposed to particular stresses.
“Large maintenance and repair jobs in the marine sector are often carried out during dry docking. However in the case of the offshore sector large repairs to deck systems must be avoided at all costs. Difficulties associated with personnel space and access to the work area make this a costly and disruptive process.
“Hempel is addressing this by promoting heavy duty grip systems that can be easily applied in a single coat so as to cause minimal disruption. Hempel’s Spray-Guard product is easy to apply at a thickness of up to 3 mm and comes with several NORSOK approvals. It is widely utilised in the offshore sector.
“For specialist markets such as the offshore facilities, it is important for access and escape routes to be maintained in good order so as to avoid disruption to day to day activities.”
Cruise control
In the specialist cruise and river cruise sectors, Bolidt of the Netherlands enjoy an enviable 70 to 80% of the market, including all new builds coming out of France and from the Meyer Werft and Meyer Turku yards, and all of Viking River Cruise and Holland America’s ships.
The company started with preparation coatings to level and provide corrosion protection beneath teak or rubber top coats on livestock carriers. They developed through fishing fleets and navies to the luxury cruise sector, but purely functional deck coatings still account for 15 – 20% of their business.
Resin-based coatings turned out to be very suitable for these strictly functional applications, and very long-lasting – Jacco Van Overbeek, Director of Maritime Division at Bolidt says: “I have yet to see a renewal needed even with ships working for 10 or 15 years, some as long as 20 years, with the same deck coatings.”
Bolidt are now best known for decorative resin deck coatings on cruise ships and mega-yachts, with products such ‘Future Teak’, and bright colour creations for the decks of Disney and other cruise operators.
Cruise ships need decks that are soft as well as anti-slip, for the benefit of passengers wearing casual footwear. Resin creates a combination of slip resistance and durability, says Van Overbeek. “The technology has now advanced to include a combination of softness and ease of cleaning. Future developments are coming in the form of self-cleaning decks, where we can now overcome the difficulty of combining anti-slip qualities with self-cleaning.”
Glow-in-the-dark coatings, a new development, are incorporated in the new Harmony class ships, for both decorative and safety reasons: they provide floor lines to follow if the lights fail, and mark the edges of swimming pools at night.
Tolerant
Chemco, based in Scotland, produce wet-and-rust tolerant coatings for most marine areas, and increasingly see them being applied on decks. Marketing Coordinator Ian Gold says: “The coatings we utilise for decks on all types of ships are the same Epo-chem coatings which we use inside of tanks and for external structures.
“The unique characteristics of these products allow them to be utilised in almost all vessel areas. To make your products non-slip, you simply add an aggregate. There are various aggregates available dependent on application area.”
Fast turn-around
The wet and rust tolerant nature of the coatings were important for ship management company Norbulk Shipping, who required a coating with a fast turnaround for their Ro-Ro ferry service from Marseilles to North Africa. The main traffic deck had severely deteriorated due to weathering and heavy traffic. Norbulk required a system that could be applied with minimum surface preparation, fast drying, high build, and quick cure to enable the refurbishment to be carried out in 48 hours so the ship could return to normal service.
Their chosen solution was one coat of Epo-chem RS 500P at 200μ DFT, a solvent-free, wet & rust tolerant system designed for excellent adhesion to high-pressure washed surfaces, with fast drying/curing properties and good abrasion and impact resistance.
The company’s products were also applied to the heavily corroded decks of a crude oil tanker whilst the vessel was at sea. Grit blasting was not permissible, so surface preparation was by High Pressure Water Jetted (HPWJ) to WJ-3 standard, to prepare the surface and remove salt and other contaminants. The coating application then had to take place in high humidity, using two coats of wet & rust tolerant Epo-chem RL 500PF.
The solution resulted in substantial time and cost savings and was successfully completed whilst at sea, with no disruption to vessel operations.
For the future
Hempel’s Simon Daly adds that flexibility and versatility are vital when providing coating solutions for marine customers: “Construction flexibility and versatility is vital when providing coating solutions for our customers. For some deck areas, there is an increased drive to utilise standard products used to create an increased grip system by mixing them with a suitable aggregate. The aggregate particle size can be varied depending upon the coating thickness required.
“We are also seeing a desire to introduce non-slip grip systems for vessels and facilities in more arduous areas such as the Arctic. There is an increased focus on anti-icing coatings from operators in these areas, often using coatings in conjunction with other ice prevention techniques.
“R&D is very important to Hempel and we continue to invest to ensure our customers get the best-in-class solutions.”
Bolidt’s Van Overbeek says even more innovative deck coatings are on the way, including a proximity-sensing function built directly into the floor coating, able to sense proximity in the same way that a smartphone screen senses the difference between a finger and an inanimate object. “We still don’t know all the potential applications of this,” says Overbeek, “it is still very much in development.” Some ideas for use include security, where the coating could sense intruders, and safety, where the presence of people in an area could be identified in the event of an emergency. It could also be used to control lighting and other systems.