Ballast Water Management

Purpose of Ballast Water Exchange :

The ballast water exchange is carried out to minimize the risk of transfer of harmful aquatic organisms and pathogens via ships ballast water and sediments.

The ballast water exchange not to be undertaken :

→ Heavy weather, high seas / swell affecting vessel’s sea keeping or gentle motion in seaway.

→ Non-availability of personnel to manage the ballast exchange process.

→ General safety of personnel and high wind conditions, compromising of crew on deck.

→ Sub-zero weather and icing condition.

→ Vessel’s inability to pre calculated stability and stress for the whole process.

Main requirements of the BWM Convention :

→ Ballast water exchange should conduct at least 200 nautical miles from the nearest land and in water at least 200 meters in depth or in cases where the ship is unable to comply with the above, as far from the nearest land as possible, and in all cases at least 50 nautical miles from the nearest land and in water at least 200 meters depth.

→ Ships performing ballast water exchange, should do so with an efficiency of at least 95% volumetric exchange of ballast water. For ships exchanging the ballast water by the pumping-through method, pumping through three times the volume of each ballast tank will be considered equivalent to meeting the 95% standard.

→ Ships treating ballast water should adhere to a specific performance standard (the D-2 Standard), which sets stringent levels of organisms by volume in ships’ ballast water discharges.

Contents of Ballast Water Management Plan :

→ Ship’s particulars including the Officer in charge of BWE operation.

→ Duties and responsibilities of the Person in Charge of BWE and record keeping.

→ Entries required in BWM log:

           → Record of ballast water management onboard.

           → Narrative of events related to MWM onboard.

           → Accidental or other exceptional uptake or discharges of ballast water.

→ Ship specific ballast water arrangement including ballast tanks and pumping arrangement.

→ Ballast water exchanging method for each ballast tank.

→ Example condition for pre-calculation & planning BWE.

→ Safety procedures to be followed while planning a ballast water exchange.

→ Warning on unsafe conditions for carrying out ballast water exchange.

→ Stresses and FSE during BWE operation.

→ Maximum / minimum drafts forward & aft, trim for propeller immersion and bridge visibility.

→ Crew training & familiarization procedures.

The factors during Sequential Method :

→ Shifting of ‘G’ during de-ballasting & ballasting.

→ Excessive stresses in seaway.

→ Free surface effect.

→ Emptying of certain tanks may lead to significantly reduced stability, higher vessel structural stresses, high sloshing pressures and/or reduced forward drafts which may then increase the probability of bow slamming.

The factors during Flow-through Method :

→ Vessel structural stresses that may be involved with conducting ballast water exchange.

→ Over-pressurization of a ballast tank or pumping equipment, which may lead to structural damage.

→ Ballast water exchange is not to be undertaken due to adverse weather, design limitations, equipment failures, loss of power or other extraordinary circumstances that could threaten human life or safety of the vessel.

→ A flow-through method that has water flowing on the deck is not recommended. The use of collecting pipes, internal overflow pipes or interconnecting pipe/trunk arrangements between tanks is to be used to avoid water flowing on the deck.

→ The flow-through method is not to be performed in weather conditions that would result in icing.