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Hempel’s range of TBT-free marine coatings not only benefit the environment – they can save shipowners time and money

The shift in technology we are about to see, where well-known and proven TBT-based technologies are being replaced by new TBT-free types, prompts the same questions from many in the maritime world. Why make the change when we have well-performing products?

The answer is that decades of discussions have concluded that the environmental effects from TBT technologies are undesirable, while suitable alternatives are available.

High performers
In general the performance of new TBT-free technologies is now on the same level as the old TBT-based products. The latest generation of antifoulings available on the market, providing service time of up to 60 months, basically consists of three different technologies – fibre-based (such as GLOBIC) on the one hand, or products based on two types of acrylated polymers.

The use of fibres in a wide range of products took off (literally) with the space industry some decades ago. Just think of Kevlar, 20 times stronger than steel, or fibreglass, widely used for leisure boats and even aircraft.

Hempel has chosen fibres because they have extremely good performance in TBT-free antifouling paint. The dry paint film is strong and flexible, the polishing rate is constant over the years, and it is possible to obtain a high volume solids (VS) in the product.

The fibres embedded in the paint film form a three-dimensional structure with high resistance to physical impact. As the paint polishes during service and thereby reveals new fresh layers of active ingredients, the fibres protrude from the paint film. These free parts have served their purpose and, as they only have mechanical strength when they are encapsulated by paint, they will subsequently break off in minute fragments.

The fibres also allow a larger amount of binders in the paint, resulting both in better control of the polishing and the highest VS (60%) for a true self-polishing paint on the market today.

Hull roughness
The fibres used in GLOBIC are synthetic microfibres which break off in step with the polishing of the antifouling paint. Several measurements of average hull roughness (AHR) on vessels with GLOBIC actually show lower AHR than vessels with TBT-based paints.

GLOBIC was developed in the early 1990s. The first test applications took place in 1995 and the full range, with three different polishing rates, was launched commercially in early 2000. Since then GLOBIC has been applied on more than 1100 vessels of all types, from small fishing boats to the largest container ships and VLCCs in the world.

GLOBIC can be specified for up to 60 months service life on the vertical and flat bottom, and so can cover the highest requirements. Based on the GLOBIC development, HEMPEL has developed two more products for lower requirements and shorter service time, OCEANIC and OLYMPIC.

OCEANIC is a cost-effective, TBT-free, self-polishing antifouling with high volume solids which can be specified for up to 36 months on vertical bottoms and 60 months on flat bottoms.

OLYMPIC is an economical, TBT-free, self-polishing antifouling which can be specified for up to 36 months.

Fouling release
Another alternative to TBT-based antifouling is fouling release (FR), such as HEMPASIL SP-EED. FR is a smooth and slippery coat where fouling simply cannot adhere. HEMPASIL SP-EED is based on silicone and provides a self-cleaning surface if the vessel is travelling at high speeds (above 25 knots) or has high activity and a reasonable speed (75% activity or more and speed above 15 knots).
HEMPASIL SP-EED is biocide-free and functions on a physical basis where antifoulings normally function on a chemical basis. HEMPASIL SP-EED does not polish, and re-coating is not necessary when drydocking takes place within the first 3-5 years. HEMPASIL SP-EED is ideal for passenger vessels with frequent drydocking intervals since only washing is necessary (except for areas with mechanical damage) before undocking.

Also vessels with lower speed or no speed at all can benefit from fouling release. If speed will not do the job it is very easy to clean a surface coated with HEMPASIL SP-EED.

Facing the future
HEMPEL is concerned about the future. By introducing GLOBIC, OCEANIC, OLYMPIC and HEMPASIL SP-EED, HEMPEL has completed the technology shift to TBT-free and provided new products for all operating requirements and demands.

Website: www.hempel.com

www.hempel.com