Basically, systems prevent organisms, including invasive species and pathogens from being transferred from one ocean to another in ballast water. The standards laid down by the U.S. Coast Guard are that vessels must:-
- Discharge less than 10 living organisms greater than 50 microns per cubic metre of ballast water.
- Discharge less than 10 living organisms in a size range 10-50 microns per millilitre.
The USCG requirement is based on organisms being live/dead. The IMO requirement is based on organisms being viable/unviable (live or unable to reproduce).
The USCG has already introduced legislation for commercial vessels which is being rigorously enforced. The IMO ballast water convention was ratified on the 8th September 2016. Vessels must be compliant by September 2017.
If the length of your yacht is greater than 50 metres and it has a ballast water capacity larger than 8 cubic metres, then you will have to comply with the IMO regulations.
If your yacht is smaller than this, but undertakes voyages from one ocean to another, you will still have to comply with the discharge standards, but these could be achieved by methods such as ballast water exchange. However you would still need to implement a Ballast Water Management Plan and maintain a Ballast Water Record Book.
If your yacht is less than 25 metres in length, then it is classed as a recreational vessel and is exempt from the regulations. Superyachts are defined in a number of different ways by the US authorities, depending on the size and the number of passengers.
Under their definition, a passenger vessel will be of at least 100 gross tons carrying more than 12 passengers, including at least one passenger for hire or it may be chartered and carrying more than 12 passengers. There are also definitions for seagoing motor vessels and small passenger vessels. Regardless of the precise definition, they all come under the US Coastguard ballast water rules and are required to treat ballast water before discharge.
In theory, ‘yes’, but in practice the answer is a resounding ‘no’. This is because the RO system would have to be tested and approved by the Flag State administration where the yacht is registered. This is an expensive, complicated and time consuming process which is not worth the effort.
So why have RO systems not sought IMO Type Approval for their equipment? This is because RO equipment serving a BWT system on a megayacht would have to be produced in large units and these would not be commercially viable. Furthermore, the potable water system of the vessel should never be connected to any other system for hygienic reasons and to avoid contamination with bacteria from pipes or tanks used for other purposes than storage of drinking water. Therefore, the best solution is to install a BWT system from a manufacturer who has already received IMO Type Approval for their equipment.
There is an important difference between chemical free systems, classified as G8 by the IMO, and systems involving chemicals (to a greater or lesser degree) which are classified as G9.
Obviously, it is desirable to have a G8 system because it means that no production, storage or handling of chemicals is involved. It’s also much better from an environmental perspective, particularly if this is a major aim of your overall vessel management scheme.
Beware of systems which are claimed to be chemical free, but actually involve a final process to neutralise by-products. Some BWT systems based on electrochlorination and ozone treatment fall into this category and are not truly chemical free.
In the case of retrofits, adequate space will be a major consideration and it is likely that the system will have to be fitted in modular form with the components distributed in available areas of the engine room.
For newbuilds, it may be possible to deliver and install the BWT equipment skid mounted on a ‘plug in and play’ basis which reduces the cost and time involved in installation.
You should also consider the maintenance implications. Will there be filters to clean? Does the system have a lot of expensive consumables? To what degree is it self-monitoring? Does it have a lot of mechanical parts which could go wrong?
Finally, the requirements of megayachts are very different from commercial vessels on a number of levels. When choosing a BWT system, it might be a good idea to ask the suppliers if they have any experience of working in the yacht market.