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Pollution

Ballast water management

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A bulk carrier that sails empty takes on tens of thousands of tonnes of seawater, called ballast, to stay stable. It pumps that water out at the other end of the world, and every living thing in the water goes out with it. Ballast water management is the set of rules made to stop that. For business, the effect on sea life is not the main point. What matters is that pumping ballast out (deballasting) is now a treated, measured and recorded operation, and it can slow down how fast a ship loads.

The convention

The full name is the International Convention for the Control and Management of Ships’ Ballast Water and Sediments. It was adopted on 13 February 2004. It came into force on 8 September 2017, after countries took thirteen years to ratify it. In general it applies to ships of 400 gross tonnage and above on international voyages. Each of these ships must carry:

D-1 and D-2

There are two standards. The history of the convention is the move from the first to the second.

Regulation D-1 is the exchange standard. The ship swaps its ballast far out at sea, so that coastal organisms are replaced by open-ocean organisms that will probably not survive at the port where the water is discharged. The convention requires 95 per cent of the volume to be exchanged, and pumping three times the volume of each tank through it is accepted as meeting this. D-1 needs no equipment, but it costs time, and in bad weather it also costs safety: a ship is designed to have its tanks full or empty, and an exchange at sea leaves them partly full.

Regulation D-2 is the performance standard. It sets limits on the water that is discharged. There must be fewer than 10 living organisms per cubic metre of size 50 micrometres or larger. There must be fewer than 10 living organisms per millilitre in the size band below that. There are also limits on certain indicator microbes. Moving water around cannot meet this standard. The ship needs a type-approved ballast water management system on board. Such a system filters the water and treats it with ultraviolet light or with chemicals.

D-2 came in step by step, tied to each ship's survey dates. That phase-in is over. Since 8 September 2024, every ship under the convention must meet the D-2 standard. D-1 no longer counts for compliance. A ship that had not fitted a system by that date cannot trade.

The United States is a separate regime

This point causes many problems. It is why a ship can hold a valid international certificate and still be refused entry.

The United States has not joined the convention. It enforces its own rules, mainly under 33 CFR part 151. The United States Coast Guard approves treatment systems under 46 CFR part 162. A system that a flag state approved under the IMO rules is not automatically accepted in United States waters. There is a bridge between the two, called alternate management system acceptance. Under it, the Coast Guard accepts a system approved abroad for a limited time. It is meant as a temporary route, not as permanent equal treatment.

The practical rule for a broking desk is short. For a voyage to the United States, IMO compliance is not the question. The question is this: does the ship's own system have Coast Guard type approval or a valid acceptance? And can the crew show the records to prove it? Some states also have their own rules for their waters. Discharging ballast in certain areas has separate rules again.

What it does to cargo operations

This is the part that affects laytime (the time allowed for loading and unloading). People ashore often do not see it.

A bulk carrier pumps out ballast while it loads cargo. The two rates are linked. At every stage of the loading plan, the ship must keep the stress on its hull and its stability within limits. If deballasting slows down, loading slows down too, however fast the terminal's conveyor can run.

A treatment system sits in the path of that water. Filters can block, especially in muddy or cloudy water. Many loading berths are in exactly that kind of water. Ultraviolet treatment during discharge takes time. Some systems treat the water when it comes in, some when it goes out, and some do both. If a system fails, the ship may have to use a backup measure agreed with the flag state and the port state. It cannot simply pump. Any of this can slow a loading rate that the charterparty (the charter contract) set as a fixed number of tonnes per day.

There is a matching question at each end. At the load port: may the ship take on ballast there? At the discharge port: may it discharge ballast there? Some ports and regions restrict both. A ship that cannot take on ballast normally cannot sail at its planned draught. See loadable quantity, which looks at the same kind of problem from the cargo side. The number a ship can really work with comes from physics, not from a headline figure.

Who carries the risk

The owner must make sure the ship complies. The owner fits the system, maintains it and holds the certificate. Under a time charter, the charterer gives the ship its orders, so in some cases part of the risk moves to the charterer. Say a charterer orders a ship to a port where it cannot legally take on ballast. Or the charterer sends it to United States waters with a system that is not accepted there. In both cases the charterer sends the ship into a problem that the owner cannot fix quickly.

The charterparty clause decides this, not the convention. The checks to make when fixing (agreeing the deal) are few. For a voyage anywhere: does the ship have a working, type-approved system and a valid certificate? For a voyage to the United States: is the system approved or accepted by the Coast Guard? For a fast load rate at a muddy berth: has anyone asked how fast the ship can deballast with the treatment system running? The original trim and stability booklet does not answer that.

What the record book is for

The oil record book under MARPOL Annex I works the same way. The ballast water record book is the first document an inspector reads. The faults it shows are common and easy to avoid: entries not signed, positions missing, or a gap between an operation and its record. A correct record, written at the time, is the cheapest protection there is. A wrong record turns a technical problem into a question of whether the ship can be trusted. The inspector who reads it is the one person who can detain the ship.

References

The MARPOL annexesSix annexes, six different things a ship may not put into the sea or the air. Which are optional, which need record books, and which cost freight. Port state control and detentionsA detained ship cannot do its job. What an inspection records, and how to read a ship's record without judging it on a single inspection. What a ship can actually liftA 58,000 deadweight ship does not lift 58,000 tonnes, and at a shallow berth it may not lift 52,000. The sums, written out step by step. How to calculate laytime and demurrageWhen the clock starts, what stops it, how the demurrage figure is worked out, and why most claims fail on the paperwork, not on whether they were right.

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