Marine coating terminology and the coating types
“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 South African 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.
“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.
- One-part polyurethane: A high solids topside paint that is easy to apply and to touch up if damaged. For interior and exterior surfaces.
- 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.
- 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.
“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:
- 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.
- 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.
Deck paint and tank coatings
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.
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.
Get in touch with South African marine paint suppliers
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 product||Coating type||Product description|
|AkzoNobel International Perfection Gloss||Two part polyurethane topside paint||High gloss paint with UV filters suitable for GRP/FRP, steel, aluminium, carbon fibre, epoxy composite, and wood.|
|Hempel Ocean Performer 7110E||Two part cuprous oxide based eroding antifouling||An eroding antifouling suitable for glass fibre, wood, plywood, steel and ferro-cement substrates. For cold, temperate, and warm waters.|
|Jotun Jotaguard 690||Two part polyamine cured epoxy cargo hold paint||Fast drying coating with high mechanical strength, specifically designed for cargo holds. Suitable for carbon steel and steel substrates.|