Hull Surface Treatment - HST - Overview

Australia | South Pacific


A Truly Remarkable Anti-Fouling Technology

HST assists ships to travel faster through the water, consume less fuel and emit lower green-house gases, ensuring that their hulls are clean and smooth – free from fouling organisms such as slime, algae, weed and/or molluscs. An effective anti-fouling technology, HST also ensures that hull fouling on commercial and military shipping is reduced/eliminated as a vector for the introduction of Imported Marine Pests (IMPS).

An exhaustive R&D program undertaken by Commercial Diving Services Pty Ltd Australia over 5 years resulted in the commercialisation of an innovative energy and conservation technology designed to target hull fouling at its early stages. The issue of hull fouling is a critical consideration for shipowners. Fouling causes an increase in surface roughness and greater frictional resistance. A slime layer of only 1mm thickness can cause 15% loss in ship speed. The loss of vessel speed caused by fouling results in increased operating costs through higher fuel costs and the inability of vessels to meet schedules.

HST Fleet
HST Research

In the past 50 years Commercial Diving Services have observed the fouling process on many hundreds of ships around Australia. Ultimately, it was the banning of 'in-water' hull scrubbing that motivated their owners (Keith & Tim Johnson) to pursue a viable alternative. Research conducted by the Sea Systems Group within the United Kingdom's Ministry of Defence and Navy Fleet HQ in 2007 has confirmed that hull-fouling reduces the effectiveness of a vessel with marked increases in fuel consumption and a reduction in top speed. Research conducted by the US Navy in 2002 proved that the speed loss of an aircraft carrier caused by heavy fouling was 1.5 knots, with a 40% increase in fuel consumed to maintain a speed of 20 knots.

Marine fouling has an immediate and potentially severe effect on ship performance. Any roughness on a ship hull that disrupts the laminar flow along the hull will produce drag. When a ship hull has been recently serviced, undergone complete sandblasting and painting, the hull will be as smooth as possible. Entering service, the hull will gradually roughen with time as a function of paint erosion and damage, fouling accumulation and corrosion. This roughness will increase drag and correspondingly propulsive fuel consumption. The magnitude of additional fuel use is quite variable, depending on the amount of fouling, the shape of the hull, and the speed at which the ship operates. Fuel penalties in the range of 10 to 25 percent have been observed on US Navy ships during sea trials. (

Typically, there is a progression of attachment of marine organisms to a painted hull. The toxicant acts as a deterrent to the attachment of higher forms such as barnacles and tube worms, but will usually allow attachment of bio-films and algae to the hull within days or weeks of launching with fresh paint. As the anti-fouling paint ages and begins to lose effectiveness, calcareous forms will begin to appear, typically on sharp edges such as weld beads, bow thrusters, rope guards, sea chests and niche areas. This is then followed by a more general infestation, spreading beyond edges onto the flats of the ship hull.

The US Navy with a fleet of 300 ships... acknowledges (2009) that colonised barnacles and bio-films on the hull of their ships' translates' into roughly $US500 million annually in extra maintenance and fuel costs. HST is a clean hull technology which offers significant return on investment and will enable military and commercial fleets to operate worldwide without being constrained by local, national or international environmental laws and regulations.

HST Australian Navy

The most effective anti-fouling paint (TBT) known to the shipping industry has been banned by the IMO and can no longer be used in most ports around the world. The most effective means of removing fouling from the underwater surface of ships hulls (hull scrubbing) whilst in port or harbour has also been banned by most member nations. Currently, HST is the only successful anti-fouling technology that does not pose a threat to the environment and in fact, reduces the bio-security risk presented by international shipping.

Hull Surface Treatment (HST) technology kills marine bio-film, slime, algae and weed attached to the underwater surface of commercial and military shipping without compromising the marine ecosystem. HST is a non-abrasive system which causes no damage to the anti-fouling paint system. HST uses an innovative delivery system of 'low flow' hot sea water as its active ingredient, encapsulated in a thermal applicator which moves over the underwater surface of the ship's hull, delivering a thermal shock... killing all bio-fouling at its primary stage of development.

HST is not designed or intended to be applied to hard/tertiary fouling on the laminar sides or flat bottom of the vessel. Barnacle growth is not suitable for HST application. The best way to stop barnacle growth from colonising is don't let them settle and colonise on the hull in the first place, through the use of HST maintenance.

HST is designed to be used in a proactive and coordinated maintenance program, effectively eliminating infant marine growth (fouling) before it is able to develop and have a significant and detrimental effect on the vessels performance and fuel consumption... a pre-emptive strike as it were... terminating the spore and slime before it has a chance to develop into a major threat to the vessels performance and energy consumption.

HST is a diver-less and portable technology easily operated by a two man team from a small tender vessel or form part of an on-board crew operated system. Subject to the effectiveness of the anti-fouling paint system, the vessels global movements and prevailing climate, HST may only need to be applied twice per annum.

The HST system does not remove live organisms into the local marine ecosystems of our Ports and Harbours... but rather kills all marine slime, bio-film and algal growth and leaves it attached to the ship's hull. Once the ship leaves Port, the dead marine growth is removed by the accelerated hydraulic force of ocean and wave action over ensuing weeks effectively neutralising any risk of biological invasion from marine pests forming part of the slime, algal and weed fouling. HST does not perform physically destructive actions in the aquatic environment.

HST In Harbour

HST can be used in the ports of Sydney, Kembla, Brisbane, Melbourne, Great Barrier Reef Marine Park, Freemantle and all commercial ports in New Zealand. HST has withstood rigorous assessment through Australian Federal and State EPA's and has independent environmental certification. HST is currently being assessed by the Royal Australian Navy on war ships Newcastle, Parramatta and Kanimbla.

In 2010 HST was selected as a finalist at the Sea Trade Asia Awards in the category of Environmental Protection... chosen as one of the top five emerging Environmental Technologies in Australasia.

In 2009 HST was awarded:

  • 1st Prize at the Lloyd's List Asia Awards for Environmental Protection in the Marine environment.
  • Runner-up at the Sustainable Shipping Awards in London in categories of Environmental Protection and Innovation.

In 2008 HST was awarded:

  • 1st Prize at the Australian Business Awards in three categories. They were:
    • Innovation
    • Environmental Protection
    • Eco-Friendly technology
  • 1st Prize at the Integral Energy Illawarra Business Awards for Innovation.
  • 1st Prize at the Future World Awards for Eco-Innovation in Business.

Hull Surface Treatment technology is brilliant in its simplicity, devastatingly effective in its application and is the long term solution to the century old problem of hull fouling.

HST Fuel Saving Benefits

Fouling Extent by Area of Wetted Hull Friction + Fuel +
100% coverage of slime, occasional patches of weed 20% 12%
As above, plus 20% coverage of tube worm less than 6mm in height 30% 18%
As above, plus 20% coverage with barnacles less than 5mm in height 40% 24%
80% Coverage with barnacles less than 5mm in height 100% 61%
80% Coverage 10-15mm barnacles 150% 92%

As per research conducted by the Sea Systems Group at British Ministry of Defence in 2007

HST Savings

HST provides a significant part of the solution to the anti-fouling quest... both in terms of its environmental and commercial contribution.

HST is the environmental solution to a complex and toxic history of applying and maintaining anti-fouling paints to the under- water surface of large ships. An adjunct to the new generation of anti-fouling paints... HST will extend periods between dry-dock, promote fuel conservation, reduce green-house gas emissions and have a significant impact on Imported Marine Pests.

Commercial shipping is responsible for approximately 5% of global oil consumption estimated to be worth $US30 billion. In 2007 the annual carbon dioxide emissions from world shipping reached 1.3 billion tons.

A survey of 100 ships undertaken by Propulsion Dynamics suggests that the average fouling resistance for a Commercial ship is 30% if no special attention has been paid to anti-fouling. Their experience suggests that at least 10% may be saved on average fuel costs and they recommend that a ship's hull should be cleaned before the slimy layer of bacteria and algae turned into a layer of seaweed. These findings are consistent with both the US and UK Navy's.

For a ship that consumes 100 ton of fuel per day, at least 10 tons per day may be saved. This represents a value of approximately $US 5,000.00 per day or approximately $US 1,330,000 per year, assuming that the vessel sails for 266 days per year and fuel is $500 per ton.

HST is designed to stop/reduce the process of primary fouling before it elevates to secondary and tertiary levels. It is important to note that HST is not designed to be applied in open water anchorage or average swell exceeding 50cm. HST enables regular and preventative treatments and in so doing... saves fuel consumption, substantially reducing the carbon footprint attributable to shipping and greatly enhancing the anti-fouling paint systems applied to the world's ships.

HST technology has been patented around the world and is available for sale through Commercial Diving Services, Australia.

Niche Areas Below The Surface

NICHE AREAS: Described as areas which are protected or offer refuge and facilitate the settlement and survival of bio-fouling organisms. Examples of these niche areas are rudder hinges, bow thrusters, bilge keels, sea chests and rope guards.

HST Niche Areas
HST Niche Areas
HST Niche Areas
HST Niche Areas
HST Niche Areas
HST Niche Areas

Although the bio-fouling levels on any individual vessel may seem insignificant, the capacity of some species with pest potential to successfully breed in large numbers can constitute a threat, and the risk of incursions is multiplied by the frequency of vessel visits. Prevention of new incursions, by management of vectors to minimise the risk of introduction and translocation enables protection of the marine environment. (Australian Government, 2009).

Hull Surface Treatment (HST) technology has evolved and not only provides an effective anti-fouling treatment to the laminar flow areas of commercial shipping, but is now capable of applying thermal shock to those niche areas described above. In response to numerous meetings with State and Federal regulators and at the request of Federal authorities, and in consideration of the IMO'S and the Australian Government's Clean Oceans Policy , Commercial Diving Services has developed a new and effective HST technology specifically designed to terminate tertiary fouling . This more specialised and detailed treatment does require diver intervention using a much smaller hand-held HST thermal application.

The HST Niche applicator (HSTNA) is a lightweight, portable and adaptable device able to effectively negotiate the various shapes and angles associated with Oil Rigs, off-shore structures, sea-chests, bow thrusters, rope guards, sea inlet pipes and overboard discharge. This process is capable of delivering a fatal 'thermal shock' to all levels of bio-fouling and is identical in terms of the patented technology established for Hull Surface Treatment (HST) technology.

The National Strategy For Introduced Marine Pest Research and Development 2006-2016 clearly identifies the impact marine pests can have on the environment, economic and social health worldwide. This strategy identifies the three main elements of the National System as prevention, emergency management and ongoing management and control. The underlying philosophy of Hull Surface Treatment (HST) technology is one of proactive treatment of all laminar flow areas, and at the same time treating the Niche areas with the much smaller HSTNA. If this process is undertaken on a regular programmed basis, the risks associated with marine pest incursion can be significantly reduced. However, the HST (patented) technology can also be used in a reactive scenario where there is a bio-security risk identified.

Research and development undertaken by Commercial Diving Services Pty Ltd proved that a diver operated hand-held thermal application will deliver terminal and permanent eradication of the target species. The design of the hand-held application allows for variable temperature control (50 to 90 degrees C) delivered at the interface.

Commercial Diving Services Pty Ltd acknowledges the importance of dealing with bio-fouling at its infant/juvenile growth cycle. A pre-emptive and proactive strike at infant/juvenile bio-fouling as part of a programmed maintenance regime will reduce the environmental risks. As a primary provider of repair and maintenance services to the shipping industry, Commercial Diving Services has encountered bio-fouling at its various levels on thousands of occasions. Our expertise in this area is what underpins Hull Surface Treatment (HST) technology and advancement into the treatment of Niche areas on commercial vessels, oil rigs and off-shore structures. A risk management approach to reducing the likelihood of introducing and translocating marine pests and preventing marine pest incursions is often more cost effective, technically feasible and practicable than attempting to control and eradicate new or long-established populations. However, Hull Surface Treatment (HST) technology now offers the flexibility and is adaptable and responsive to the more serious threats posed by established marine pests.

Hull Surface Treatment (HST) technology offers solutions to several key priorities in vector management, as identified at 3.1 in the National Strategy for Introduced Marine Pest Research and Development 2006-2016. V5 identifies the need to develop new treatment options for non-ballast vectors and methods to assess their effectiveness and V4 relates to the effectiveness of current treatment options for non-ballast vectors. Both these Vector Management R&D requirements are identified as High Priority.


The Environmental benefits of HST:

  • Reduces/prevents hull fouling as a vector for the transportation of ‘introduced marine pests’
  • Reduces/prevents marine biographical invasion occurring via hull fouling
  • A cost effective, environmentally acceptable and safe treatment to toxic anti-fouling paints
  • An enhancement to the active properties of new anti-fouling paints
  • Is able to be performed in a completely environmentally safe process
  • Is able to be performed in ports and harbours whilst the ship is loading or unloading
  • No damage or removal of existing anti-fouling paint system
  • No chemical or abrasive process used - no pollution to the waterway
  • Reduces fuel oil consumption by an average of 10% with regular treatment between dry dock periods
  • Reduces greenhouse gas emissions
  • Poses no threat to the economic, environmental, cultural and social fabric of marine and coastal resources

The Economic Benefits of HST:

  • A cost effective process
  • Increases fuel efficiency
  • Promotes less wear and tear on ship engines
  • Extends life of anti-fouling paints
  • Reduces periods of programmed dry-docking
  • Environmentally user friendly
  • Poses no threat to the economic, environmental, cultural and social fabric of marine and coastal resources
  • Does not destroy the anti-fouling paint system, as does abrasive brushing
  • Aggressive energy conservation initiative