Background to Environmental Hull Cleaning

It has long been known that fouling on a ship hull’s greatly increases hull friction and therefore increases the power needed to maintain speed and manoeuvrability.Technology has advanced to the point where ship hulls could be cleaned with the ship still in the water using a variety of hand and mechanical tools. Cleaning the hull with the ship in the water versus drydocking saves significant time and expense. For a brief time towards the end of the 20th century, the introduction of the highly toxic Tributyltin (TBT) into hull paints, offered the illusion that ship hull cleaning was an unnecessary thing of the past. The idea was that all the hard work required to keep a ship hull clean could be avoided, substituting chemicals, for manpower. It was soon discovered that TBT caused extensive, severe and unsustainable damage to the marine environment.  The antifouling technology which replaced TBT-laden hull paint was relatively ineffective. All ship hulls develop a biofilm or slime layer at the very least, regardless of the bottom paint used, and this, combined with rough hull coatings, carries with it a fuel penalty of as much as 20% or more.  Underwater ship hull cleaning if completed efficiently and on a suitable hull coating is the answer to reducing fuel costs, cutting Green House Gases (GHG) emissions and preventing the spread of non-indigenous species.

Significant pressure is being applied to the shipping industry towards a more efficient and environmentally safer approach to hull coating and fouling control. The influences involved are:

  1.  The rising cost of fuel
  2. Pressure to safeguard the marine environment from the harmful effects of chemical biocides contained in conventional antifouling paints
  3. The problem of accumulating pollution and contamination of ports and harbours and their immediate surroundings, along with the great difficulty of dredging or trying to clean up those areas
  4. Rising concern about harmful atmospheric emissions such as nitrous oxides (NOx), sulphur oxides (SOx), so-called greenhouse gases (GHG)
  5. Efforts to limit the spread of invasive non-indigenous species (NIS) via ship hull fouling
  6. The economic need to extend the interval between dry dockings

Clean underwater surfaces keep vessels operating efficiently, providing a reduced carbon footprint which directly reduces the environmental impact of transportation in our global fight against climate change. Many ports have banned conventional cleaning methods, which contaminate local waters by
spreading paint debris and alien invasive species.  The E300 Hull cleaning system uses diver-controlled brush carts to clean all types of vessels while they are in a port. The brush cart is equipped with a unique cleaning and collection technology which cleans the hull efficiently without damaging its antifouling paint and stops alien invasive species from spreading in the water.

The cleaning device has the ability to act as a recovery cleaner, locking on to the hull so that the wastewater is pumped back to the support vessel or quay and from there sent through a filtration processing system. No contaminated waste is released to the local environment.

OSC Marine’s vision is to provide technology that ensures our environment is protected and optimises the performance of visiting and resident vessels. We will endeavour to set new standards for in-water cleaning and environmental services.

History of the – OSC Marine E300 Hull Cleaning System

The E300 Hull Cleaning System was developed through trials and modifications by its original designer over a 20-year period. The E300 Brush-Cart and Hull cleaning methods have proven to be an effective Hull cleaning system with an efficient and reliable deployment system.   During 2017 and 2018, extensive design and testing was completed by the OSC Marine Group technical and engineering team. With the requirements of Bio-Security and the protection of our world harbours, further enhancements including the recovery and filtration systems have allowed the E300 Hull Cleaning system to maintain its effectiveness yet recover and process the material from vessels in a compliant manner. In addition, significant safety features have been added to the system for diver safety and enhanced observation of the work scope.

In-water cleaning of the immersed hulls of vessels can be employed to:

  1. Remove slime and biofouling
  2. Remove biofouling growth after periods of vessel lay-up or low activity
  3. Maintain foul release or scrub-able coatings
  4. Contain and remove potentially invasive marine species
  5. Arrival of a heavily fouled vessel at a port of first entry, requiring urgent management of gross general fouling
  6. Arrival of a vessel with patchy fouling (for example, of niche areas), including patchy fouling of identified unwanted species
  7. Routine cleaning to maintain minimal fouling on the hull.

OSC Marine operates in Cape Town, Durban, Saldanha, Richards Bay, Mossel Bay and Port Elizabeth. We provide compliant services to most Class societies for all vessel and Rig husbandry. Contact us at info@oscmarine.com.

Certificates – Hull Cleaning Permit – Durban
Certificates – Hull Cleaning Permit – Saldanha HULL-SLD-2018-02

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