The new International Convention for the Control and Management of Ships’ Ballast Water and Sediments was completed and adopted in February 2004. When 30 states, representing 35 percent of the world merchant shipping tonnage, have signed the Convention it will enter into force 12 months later. It is difficult to forecast when this will happen.
However, requirements for acceptable ballast water management methods and planning have entered into force in several states.
Ballast water exchange
These are the three methods used to exchange ballast water:
Flow through method
A process by which replacement ballast water is pumped into a ballast tank or hold intended for the carriage of water ballast allowing water to flow through overflow or other arrangements. At least three times the tank or hold volume shall be pumped through the tank or hold.
Sequential method
A process by which a ballast tank or hold intended for the carriage of water ballast is first emptied of at least 95% or more of its volume and then refilled with replacement ballast water.
Dilution method
A process by which replacement ballast water is filled through the top of the ballast tank or hold intended for the carriage of water ballast with simultaneous discharge from the bottom at the same flow rate and maintaining a constant level in the tank or hold. At least three times the tank or hold volume shall be pumped through the tank or hold.
The ballast water exchange:
- has to be done 200nm from nearest land and in water at least 200 metres in depth
- in cases where the ship is unable to conduct ballast water exchange as above, this should be as far from the nearest land as possible, and in all cases at least 50 nm from the nearest land and in water at least 200 metres in depth
- when these requirements cannot be met, conduct ballast water exchange in designated ballast water exchange areas.
Ballast water treatment
The ballast water exchange methods will be phased out as an acceptable method of complying with the Convention. In the time period 2009 to 2016 depending on ballast capacity and date of keel lay only ballast water treatment will be acceptable. After this period all merchant ships will have to use ballast water treatment to comply with the Convention.
The methods of treatment are under development. The options being considered include:
- Mechanical treatment methods such as filtration and separation
- Physical treatment methods such as sterilisation by ozone, ultra-violet light, electric currents and heat treatment
- Chemical treatment methods such adding biocides to ballast water to kill organisms
- Various combinations of the above.
National requirements
As of now, these are the different national requirements regarding ballast water management.
Australia
- BW Exchange outside Australia’s territorial sea (12 nm)
- Exception based on risk assessment
- Ballast Water Report
USA
- BW Exchange 200 nm from any shore
- Ballast Water report (penalty < $27,500 US)
- Ballast Water Plan
Canada
- BW Exchange depth > 2000m
- Ballast Water report (submitted)
- Ballast Water Plan (reviewed by Flag Adm. or Class)
New Zealand
- BW Exchange on the high seas
- Ballast Water report (completed)
Argentina (Buenos Aires)
- Chlorination (from areas where cholera is endemic)
Chile
- BW renewal >12 nm from the coast
- Documented in bridge and engine-room log
- Alternatively chemical treatment
Israel
- BW Exchange in open sea:
- Elat: outside Red Sea
- Mediterranean port: Atlantic ocean - BW reporting form (port representative)
Brazil
- BW Exchange (depth > 200m, from coast > 200nm)
- BWM Plan
- BW reporting form (harbourmaster)
Panama
- Discharge of ballast water prohibited
UK
- Some ports: discharge to onshore reception facility
Please note:
The list is not exclusive and there may be changes in requirements. Therefore, we kindly request that Members make sure that they know the ballast water exchange requirements in the ports they are calling.
Safety issues
Stability:
- All intact and damage stability requirements applicable to the ship shall be met.
Strength:
- Sheer force and bending moment: Within the limits at all times
- Slamming and sloshing: Considerations of sea and weather conditions
Visibility, propeller immersion and draft forward:
Can be given special consideration when:
- In open water
- Low traffic density
- Enhanced navigational watch
- Manoeuvrability not impaired
- Suitable sea and weather conditions
System failure
- Over/under pressure of tanks
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