Baby smooth

The polymer commonly used in the making of teats for baby bottles lies at the heart of Jotun?s latest launch.

As environmental awareness has grown, so have restrictions on a number of different substances. One compound that is on the way out is the use of TBT in hull coatings. Should draft regulations currently in hand at IMO enter into force then TBT will be banned from use as an anti-fouling coating.

This has led paint makers in a search for alternative solutions, and the past few years have seen the launch of a number of tin-free alternatives. Unfortunately, there have been problems. In general none of the new breed have performed as well as existing coatings and have, in many cases, proved to be more expensive.

Now Jotun Paints says its solution – SeaQuantum – has been extensively tested and can meet, or exceed, shipowner?s requirements. It is tin free and, in its ultimate configuration can provide protection for 60 months. However, it is nearly four times the price per litre of existing TBT anti-foulings. Jotun believes that this is not an issue, since shipowners will have to switch from applying TBT by 2003, with a complete ban following in 2008. In that context Jotun feels SeaQuantum will be competitively priced.

Developed in conjunction with Japan?s Nippon Oil and Fats, the coating is based on a hydrolysable silyl polymer with copper additives. Notes Jotun: “In the longer term we expect copper content to be reduced and it may be entirely replaced”. Removing copper is described as one of the challenges faced in the development of the next generation product.

One of the key features of the new range is the claim that the anti-fouling leaches to form a much smoother skin than comparable TBT-based products. Jotun says it takes about three months of service from application for the coating to reach optimum smoothness. In addition, since the coating?s ability to leach is based on hydrolysis, rather than hydration, the coating is hard, which avoids the problems associated with soft coatings.

Jotun notes that while some success has been achieved with hydrating tin-free anti-foulings the absence of organo-tin compounds result in reduced performance. In such cases Jotun says that a non-constant polishing rate reduces the effective life to three years, while the initial hull roughness remains unaltered in service. This means there is no benefit of decreased fuel consumption.

By contrast, Jotun says these problems have been overcome by SeaQuantum. It has conducted extensive in service tests including those on the 1996-built, 302,789 dwt VLCC Olympic Legacy. The fuel consumption of the ship was analysed over 30 months with the ship trading in a number of conditions ranging from fully laden to ballast. Strong wind and rough sea effects were eliminated from the analysis.

The results indicated that there was an average cost reduction of 7.5 per cent, which equated to $333,000 against a bunker spend over the period of $4.5 million. The savings have to be balanced against the cost of coating the ship, which was not revealed.

Jotun comments that the one-pack, high-build coating – it has a solids content of 52 per cent – could be applied at any temperature, and was resistant to cold flow problems. In addition the company remarked, in response to a query, that it would guarantee the product up to 60 months and that this guarantee was centralised and would apply world-wide.

Although Jotun says that can be applied over existing anti-foulings, its recommendation is that the coating should be applied on a completely blasted hull. “We believe that the surface should be perfect, and that shipowners will not want to sandwich older coatings,” it remarks. To meet individual requirements Jotun will discuss alternative application strategies, but believes that owners that prepare for 2008 now will gain greater advantages.