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Controlling Hull Fouling: Behind the scenes of what keeps your ship ticking

The relation of hull condition to fuel efficiency is no rocket science. For oceangoing vessels, there are opposing processes: for instance, the faster the ship moves through the water, the slower the growth of marine life on the hull; on the other hand, the more marine life that grows on the hull, the greater the resistance against the ship which in turn results in slower speeds and lesser distances covered.

The Clean Shipping Coalition estimates that a ship owner can ascertain fuel savings of 15 to 20 percent if the optimal coating technology were matched to vessels, properly applied and maintained. There is a corresponding decrease in emissions to be enjoyed as well. Even a small amount of smooth surface disruption on a ship propeller or hull can produce enough turbulence to reduce fuel efficiency. Therefore, there is good amount of reason to take proper preventive measures against the hull fouling of a ship.

Biofouling also has an adverse effect on the marine ecology of ports. The deep water vessels that transport cargo across vast oceans also have a propensity to transport viable marine life. These ships can carry invasive species which can harm the regional ecologies and the mechanisms for transporting these are regulated by the International Maritime Organization.

Comprehensive guidelines have been established by IMO with respect to biofouling. For oceangoing vessels, it is very important for all stakeholders – both ashore and crew members on board– to keep the hulls of their ships free from fouling. This influences both economic and environmental bottom lines. Another area of concern are ballast tanks as these can be breeding grounds for invasive species; a far greater challenge deep water vessels compared to brown water workboats.

Fouling-control coatings include Anti-Fouling (AF) coatings and Foul-Release (FR) coatings. The former rely on biocides; the latter decreases adhesion strength through the mechanical properties. AF coatings typically are sacrificial coatings. They gradually wear off to expose fresh layers of biocide agents. But we must also take into account the harm done to environment by these coatings, from surface preparation efforts to paint application. Use of various coatings must be balanced against the other downstream consequences such as fouling, increased GHG emissions, etc.

It is of paramount importance that we know a vessel’s operating profile, because only after that is it possible to build a system that provides a five-year antifouling performance. Software can be used along with the operating profile to calculate film thickness. In this manner, the AF coating can be tailored to the needs of the customer, providing a much better fuel economy by controlling the roughness of the hull.

Another factor that we must consider is the method used to clean the ship’s hull. The cleaning schedule and methods depend upon an intimate knowledge of fouling processes. The adhesion of marine life to the ship hull depends on the type of coating as well as the species. The cleaning method chosen will depend on the degree of fouling or biofouling and the potential for the cleaning method to damage the various layers of coating. There will typically be several cleaning cycles before a new coating needs to be applied.

To conclude, perhaps the best investment that ship owners or vessel operators can make is to consult with a hull performance specialist who can advise them on what are the best practices of maintaining his/her vessel based on the climate and working conditions that the boat is under.

This can also help in ensuring that a coating is applied according to manufacturer specifications and a hull cleaning regimen is also developed that maximizes the life of the vessel and also its operating efficiency. The policies recommended and the maintenance work thus done will most definitely be recovered in fuel savings, reduced downtime and longer vessel ‘up-time.’

To this end, with an unparalleled blend of expertise and technology, Alphard has been successfully carrying out Diving & Underwater services since a year now. Our diving managers & Supervisors are commercial divers with over 25 years of diving experience, who add extensive amount of value to our client's needs. We have our own dedicated Dive boats which are fully equipped with diving spreads on board which requires no loading time. More details of our services can be found at - http://www.alphardmaritime.com/index.php/home/servicesdetail/24.