Biofouling in focus – a smooth hull reduces your vessel’s GHG emissions

Biofouling can significantly increase ships’ GHG emissions reveals an IMO study delivered at this month’s United Nations summit. The Hempaguard MaX system is one of the antifouling coatings on the market that maintains a fouling free hull over five years, writes Mads Raun Bertelsen, Head of Hull Performance Solutions at Hempel.

The debut findings of a study on the impact of biofouling on ships’ greenhouse gas (GHG) emissions reveal that even a thin layer of slime on a ship’s hull can increase its emissions by up to 25 per cent.  The study was presented to the United Nations Climate Change Summit held in Glasgow, UK, 4 November.

The 12-day COP 26 summit, was attended by world leaders, giving biofouling a stage that goes beyond shipping circles. The early findings of the report were presented at a side event by the Global Industry Alliance (GIA) for Marine Biosafety – a group of companies invested in reducing emissions created by biofouling though the framework of IMO’s GloFouling Partnerships project.

Preliminary findings reveal that a layer of slime can trigger an increase of GHG emissions in the range of 20 to 25 per cent, and a light layer of barnacles or tubeworms can increase GHG emissions up to 55 per cent, depending on ship characteristics, speed and other prevailing conditions, says the IMO in a statement.

Lilia Khodjet El Khil, IMO Project Technical Manager for GloFouling Partnerships says, “Biofouling management creates a smooth ship’s hull, and this will reduce friction and thereby reduce fuel consumption and associated GHG emissions. Biofouling management is an important part of the roadmap to a decarbonised future.”

Biofouling – the accumulation of various aquatic organisms that gather on ships’ hulls – increases the drag as a ship moves through the water and so more propulsion energy is needed which in turn increases fuel costs and carbon emissions. These organisms can also play havoc in marine habitats if they detach from the hull and reproduce in areas where they are non-native often taking over the habitat and endangering indigenous species.

Regulations in practice

To minimise the movement of non-indigenous species (NIS) through biofouling, IMO has made recommendations through its Marine Environment Protection Committee resolution (MEPC.207(62)). It calls for planned periods between drydocking to remove and assess any biofouling, the application of different anti-fouling systems, including paints and coverings, bearing in mind the specific speeds the ship intends to sail at, and the regions it will travel in – whether Arctic or tropical. In most cases all of these elements – sailing speed and water temperature along intended routes – influence the type of antifouling system applied to the ship’s hull.

Further, every aspect of a ship’s operation will be under increasing scrutiny as shipowners and operators seek to reduce their vessels’ emissions and increase their performance from both a regulatory and competitive standpoint. The IMO’s greenhouse gas strategy is being rolled out through holistic approaches to emissions reduction such as the Energy Efficiency Existing Ship Index (EEXI), which scores vessels for their efficiency. IMO is calling on ports and other stakeholders to offer incentives to the owners/operators of higher scoring ships.

These two IMO mechanisms require ship operators to look to their fleet and ensure that correct biofouling management is in place to reduce ship emissions and preserve ocean diversity.

Further, good biofouling management will result in significant cost savings through reduced fuel consumption – an important consideration given the recent uptick in bunker prices across the globe.

Central to the success of any biofouling management plan is the coating on a ship’s hull. Hempel, the global coatings manufacturer, fully appreciates the complexities and impact of fouling and draws on more than 100 years’ experience to develop ground-breaking trusted coating solutions. The company’s most recent fouling defence coating system – Hempaguard MaX – has become an industry game changer. 

Any water, any speed

Hempaguard MaX enables operators to slow steam their ships through waters of any temperature, tropical or otherwise, whilst minimising fouling on the hull. This innovative coating delivers an impressive 8 per cent out of dock power reduction compared to best-in-class antifoulings and extremely low average speed loss¹ of 1.2 per cent, regardless of a vessel’s trading pattern. 

With the three-coat system, each layer brings its own protective qualities, but the real strength is in the synergies between the layers. Hempaprime Immerse 900 is an anticorrosive primer that can be applied in one coat and forms the base coat, protecting the steel hull from corrosion. It also helps deliver the super-smooth surface required to fight off fouling. Nexus II is used as the intermediary, or tie coat, with improved anticorrosive capabilities. Together, they provide the same protection delivered by two standard maintenance epoxy coats, and ultimately save money for the shipowner and operator. 

The final layer, Hempaguard X8, performs the fouling-defence role. Built on the success of Hempel’s leading hull coating Hempaguard X7, the topcoat – Hempaguard X8 – is the driving force behind the unrivalled antifouling performance. It incorporates Hempel’s enhanced patented Actiguard technology that combines the smoothness of a silicone coating with an improved hydrogel microlayer and active ingredient. As the Hempaguard MaX system is applied in just three coatings (as opposed to five coats traditionally used), it can be applied much faster, and reduces time in dry dock by up to two days. This saves on expensive yard fees and limits the number of off-hire days.

Commercial and regulatory imperatives call for every aspect of a ship’s operations to be analysed in order to achieve reduced emissions status as laid out through the IMO’s greenhouse gas strategy, which calls for a 50 per cent reduction in emissions by 2050 compared to 2008. Adopting a trusted coating system such as Hempaguard MaX can make a significant difference to a shipowners’ operational success. It is the most efficient hull coating solution on the market today and even delivers a return on investment in just three months². It is the new peak in efficiency. 

Hempaguard MaX at a glance:

– Powerful advanced fouling defence coating system with increased smoothness.

– Low average hull roughness driven by the whole coating system – improving fuel efficiency.

– 8 per cent out-of-dock fuel savings driven by a low friction hull compared against a market average coating, which can be translated directly into an EEXI improvement of 2-3 per cent speed gain.

– 1.2 per cent maximum guaranteed speed loss¹ over a five-year docking cycle, compared with a market average speed loss of 5.9 per cent.

– Three coat system that saves up to two days in dock – saving time and money.

– Improved idle time antifouling guarantee of 120 days.

1 Speed loss: If a vessel’s main engine is set at a certain power output, it will propel the ship through the water at a certain speed. Over time, fouling accumulation will increase drag and cause the speed of the ship to reduce even if the main engine power output remains constant. This reduction in speed is termed “speed loss”.

2 Based on a VLCC with activity level of 70 per cent and burning low sulphur fuel costing 35 per cent more than standard bunker fuel over a five-year life cycle. Hempaguard MaX system delivers an annual saving of around USD 1.8 million compared to a market average antifouling. This equates to a ROI (return on investment) of three months.