DOSSIER

 

Underwater cleaning standard in the offing


Underwater hull cleaning is subject to various national rules, resulting in the operation being banned in many areas within territorial waters.

This puts severe restrictions on owners and operators ability to clean hulls, propellers and rudders to gain that little bit extra efficiency and thus cut fuel consumption and save on emissions.

BIMCO is investigating the possibility of introducing an underwater cleaning standard and is already in talks with owners, coatings manufacturers and other stakeholders.

The aim is to create an ISO standard for afloat hull cleaning, possibly within a couple of years.

Deputy secretary general, Lars Robert Pedersen told Tanker Operator that the work would also include looking at the equipment involved in underwater cleaning.

Of course it not only the hull that needs regular cleaning, as rudders and propellers also require regular attention.
A little while ago, Hydrex developed a new approach to propeller cleaning. The traditional approach was to let the propeller become fouled with the build up of calcareous growth and maybe polish it in the water once or twice a year or in drydock.

This polishing is undertaken using a grinding disk, which can be quite damaging to the propeller. By using a grinding disk, a substantial amount of metal is removed from the propeller itself, which can alter its shape and efficiency, cause roughness and increase rather than reduce friction.

It can also be a source of pollution, which as mentioned is a problem in a number of ports.

Hydrex discovered that more frequent, lighter cleaning of the propeller using a different tool to a grinding disk, and catching the propeller before a calcareous layer builds up, is the optimum approach to propeller cleaning.

If undertaken correctly and regularly it can result in 5% or even more in fuel savings. Obviously for a ship that has even a medium level of fuel consumption, the savings far outweigh the cost of the propeller cleaning.

Because the propeller is being attended to regularly, the cleaning is relatively light and quick. No material is ground away, which is good for the propeller and the environment. The propeller is kept in an ultra-smooth condition (Rubert A or A+), which is where the real fuel savings can be achieved. This finish can only be achieved by in-water propeller cleaning.

Fuel prices are climbing. As new low sulfur fuel requirements come into force, costs are going to escalate. A 5% fuel saving for the ship can make a huge difference to the bottom line.

Using a network of offices and service stations, Hydrex can offer propeller cleaning worldwide. These operations are carried out using underwater equipment designed and developed in-house specifically for propeller maintenance.


Inspections offered

Hydrex also combines this service with underwater inspections where this is of an economically advantage to the shipowner or operator.

As for hull cleaning, the unique design of the Hydrex series of underwater hull cleaning units provides the efficiency and durability demanded by the harsh underwater environment, the company claimed.

All systems are carefully designed so that those hull coatings, which are suitable for underwater cleaning, are not damaged, while still completely removing all types of fouling. This restores a vessel’s performance to as clos to its optimum condition as possible and offers shipowners considerable savings in fuel.

Hydrex’s policy is not to carry out underwater cleaning activities, which result in an increase of pollution by spreading large amounts of toxic materials used in many underwater hull coatings.

Many of the machines used for hull cleaning, propeller polishing and inspections are diver operated.

However, one company that operates ROVs is HullWiper. This company was launched in Dubai in December, 2013.
Since then, the company has seen a rapid expansion take place and today, HullWiper operates in ports worldwide, including Sweden, Singapore, Spain, Netherlands, Norway, Egypt and the UAE. The company will also offer a cleaning service on an ad hoc basis at key locations across the Middle East, as the machines can easily be moved.

Another use for diverless machines is cleaning up after oil spills. Following the oil spill from the chemical tanker ‘Bow Jubail’ in Rotterdam, Dutch company Fleet Cleaner has helped the authorities by cleaning ship’s hulls which were fouled by the spilled heavy fuel oil, in order to minimise the environmental impact.

After the spill, Fleet Cleaner loaded the equipment on an oil spill response vessel. By installing specialised heating equipment, the high pressure water cleaning robot was made ready for high pressure steam cleaning.

Using the 1 MW installed power, a special oil skimmer, as well as the necessary oil booms and PPM’s, the Fleet Cleaner team undertook round the clock cleaning of the affected vessels.

The cleaning was undertaken together with the main contractor Hebo, which was contracted to clean and co-ordinate the cleaning of the entire Rotterdam port area.

Fleet Cleaner assisted in cleaning 12 oil-fouled vessels. Where standard oil spill cleaning is undertaken above water, the company’s robot was also able to clean under water. The robot was also used to remove oil at heights up to 10 m above the waterline.

An optional package will be included in future Fleet Cleaner installations for oil spill situations in other Dutch ports, the company said.

 

 

 

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