Commercial antifouling hull coatings increase efficiency across coating process and reduce fuel consumption

Marine coating protects both you and your vessel

The term “marine coating” covers a class of coatings all intended for use in the marine segment. These coatings include antifouling paints, deck paints, anti slip paints, bilge paint, boot-topping paints, and protective paints for structures in marine environments. Just as there are different types of marine paint, so there are different requirements depending on the environment, use, and material of your vessel.

Which marine coating you need is dependent on a series of factors, including local paint regulations and application methods. In this article we will provide a guide to the different paints, and what you need to know in order to choose the right one. We will also outline some of the products available in the UK.

A marine coating guide: from top to bottom

“Marine coating” covers everything from the top to the bottom of a vessel, as well as structures in marine environments. One paint does not fit all, and given that your vessel can need to deal with not only the British weather but also the conditions of the high seas and far flung locations, it is important to choose the right paint for the job. This guide will look into the different paints required for different substrates and situations.

Above the waterline – Topside paints

Topside paints are the paints used for the upper hull, interior, and deck areas of a boat, or those areas above the waterline. They protect the boat from sea, sun, sand and the bumps and scratches that will accumulate with time. Essentially, there are 3 types of topside paint: one-part polyurethane, two-part polyurethane, and alkyd enamel. All of these are resistant to moisture and abrasion, can withstand hull expansion and contraction, and resist UV damage while maintaining colour and finish.

Topside marine coating protects above the waterline

Topside paints provide protection and gloss for the upper hull

  1. One-part polyurethane: A high solids topside paint that is easy to apply and to touch up if damaged. For interior and exterior surfaces.
  2. Two-part polyurethane: Two-part polyurethanes outperform one-parts in hardness, gloss and colour retention, and UV resistance, but are more expensive and difficult to apply. They are also less flexible than one-part polyurethanes.
  3. Alkyd enamel: A one-part topside paint that is glossy and easy to apply. They require fewer coats than the two-part polyurethanes and expand and contract with the hull better, particularly good with wooden vessels. These paints require an annual reapplication for maintenance, and have the lowest gloss and colour retention of the three options.

Below the waterline – Bottom paints

“Bottom paint” is paint used to protect a vessel below the waterline. Also known as antifouling paint, its main task is to prevent the build up of sea life on a boat’s hull. This process (called biofouling) is not just an aesthetic problem; the growth of algae, microorganisms, plants, or animals on a hull also slows the ship’s maximum speed, increases fuel consumption, decreases durability, damages the hull, and can introduce invasive species into foreign waters. Bottom paint prevents this by having a biocidal active ingredient, such as copper, which destroys, deters, or renders harmless these organisms. There are two types of antifouling paint:

  1. Hard film antifouling: A hard bottom paint leaches a biocide when in contact with water, impeding marine growth without eroding the paint. It is often used for high speed vessels because the hardness of the coating will not wear due to the impact of the water. Once the biocide is leached away the paint will remain, so another coat will be needed to replenish the antifouling layer.
  2. Eroding antifouling: These coatings wear away through the friction action of being in the water, slowly reducing in thickness and exposing fresh layers of biocide as it does. This reduces maintenance as there is less paint build-up on the hull. There are both single and multi season options for eroding antifouling.

Legislation regarding biocides and bottom paint is constantly being updated, and it is important to be aware of the latest regulations. We discuss regulations further down in this article.

Deck paint and tank coatings

  1. Boat decks and structures in marine environments are hazardously slippery when wet. In order to protect passengers and employees from accidents, a vessel needs adequate anti slip protection. Deck paint not only needs to provide anti slip protection, it needs to withstand all the elements and all the wear and tear that comes with traffic. Creating an anti slip surface is as simple as adding a powder or non skid aggregate to a hard-wearing paint such as a two part polyurethane.
  2. Tank coatings are another important aspect of marine protection. Whether lining cargo tanks, potable water tanks or wastewater tanks, the right coating can save you from costly damage. Most commonly tank linings are epoxy, polyurethane, or polyurea, depending on the cargo of the tank. The lining needs to withstand and not contaminate the cargo, while also allowing for fast transfer times with cargo changes. Companies that sell cargo coatings, such as AkzoNobel, PPG, and Hempel, also provide helpful Cargo Protection/Resistance Guides, to check the suitability of the coating against your cargoes.

Where to find marine coating products and contractors in the UK

Marine coatings are applied either while a vessel is in the water (for topside coatings) or dry docked (for bottom paint). There are even coatings that can be applied underwater, for structures like jetties. For commercial and pleasure craft, there are many who chose to paint their vessels themselves. However, the security and quality of a professional coat, as well as the ease, cannot be beaten. If you would like more information on marine coatings, or would like to connected with one of our coating partners to complete your project, get in touch! Our experts are here to help, just use the “Request a quote” button at the bottom of this article and we will do the work to find your coating solution.

Marine coating productCoating typeProduct descriptionPrice
AkzoNobel International Perfection GlossTwo part polyurethane topside paintHigh gloss paint with UV filters suitable for GRP/FRP, steel, aluminium, carbon fibre, epoxy composite, and wood.£50-55/750mL to cover 9m2
Hempel Ocean Performer 7110ETwo part cuprous oxide based eroding antifoulingAn eroding antifouling suitable for glass fibre, wood, plywood, steel and ferro-cement substrates. For cold, temperate, and warm waters.£90-100/2.5L with 13m2/L coverage
Jotun Jotaguard 690Two part polyamine cured epoxy cargo hold paintFast drying coating with high mechanical strength, specifically designed for cargo holds. Suitable for carbon steel and steel substrates.£200-220/20L with 6m2/L coverage
Teamac Bilge PaintSingle component oil alkyd for bilgesA semi-gloss finish to protect the lowest inner parts of a ship’s hull, providing moderate protection against water and oil. Suitable for wood, metal, and GRP.£15/L to cover 12m2
Teamac Suregrip Deck PaintModified alkyd coating with aggregateRough anti-slip finish paint for decking inside and outside for foot and light truck traffic. Suitable for wood, metal, concrete, GRP.£20/L to cover 6-10m2

Marine coating regulations in the UK

The chemicals used in marine coatings can affect the delicate ecosystems of the marine environment. Tributyltin (TBT) was used as a biocide until it was discovered that it was highly toxic to creatures all the way up the food chain, an example which the marine coatings industry does not want to repeat. The effects of copper as a biocide are currently under scrutiny, with stricter environmental regulations being introduced across the globe. On the other hand, biofouling leads to the introduction of non-native and invasive species to an ecosystem, and also needs to be strictly controlled. The legislation which particularly relates to the UK, for everything from vessels to offshore structures, can be found at the Oil & Gas UK Environmental Legislation Website.

In the UK, the use of antifouling paints is strictly controlled by the International Maritime Organisation, the EU, and the Wildlife and Countryside Act. EU regulations relating to copper-based antifouling paints have led to tighter restrictions and regulations for the coatings industry. The clear concern for the environmental impact of these coatings has led to an increase in environmentally conscsious foul release coatings, and a greater interest in the possibilities of nanotechnology for the future of antifouling.