It is not difficult to imagine that, with some collusion between the engine operating staff, this control mechanism could easily be evaded.
An identical situation has been faced by the authorities controlling emissions levels in automotive engines and some years ago the United States authorities introduced on-board diagnostics to all new passenger cars. The approach there is to install a number of sensors to the engine and its air, exhaust and fuel systems. A central processor then monitors all the parameters which affect emissions and registers any change . These changes are allowed to occur within a certain tolerance band after which a warning light on the dashboard is illuminated. This information can be stored in an on-board processor. The next generation to be introduced will not only alert the driver of a change in emissions levels but it will take some control action such as prevention of further engine operation after a certain number of kilometres or hours have elapsed. Control by the authorities is fairly straightforward because police and others can be equipped with reading equipment which may be plugged into the vehicle system to monitor whether the emissions warning has been triggered or whether any unauthorised modifications have been made. This is known as on-board diagnostics (OBD) and it is well established in the United States. The European approach known as E-OBD was introduced this year as shown in Fig.1 along similar lines.
Every change to an engine design or modification made must in future comply with the OBD requirements. This approach is more straightforward on a gasoline engine than on a diesel but diesel engines in cars and trucks will inevitably be controlled by a similar OBD system.
To apply this approach to a ship would seem to be relatively simple provided sufficient numbers of sensors with adequate durability can be installed at an economic price and some method can be devised to prevent tampering or hacking into the software of the system to evade it. Also to be considered is the question of what should be done when an increased emissions alarm is raised. Clearly it is unacceptable to have an automatic shut-down of the engine because of the risk to the ship and to personnel. Some sealed black box flight recorder type device to alert the authorities during the next inspection seems possible. Alternatively a satellite link to a central monitoring centre could be made quite easily and cost effectively with today's technology.
If this is the ultimate approach which must be used we have to consider how it can be co-ordinated and implemented. It is one matter for the United States Environmental Protection Agency to provide funding for the development of OBD systems and then insist upon their introduction or even for European authorities to follow suit. It is another matter as to whether the IMO or any other world authority could achieve the same amount of control for engines on-board ships. As is often the case we have a technical and economic solution but we still seek a political solution.
The emissions reduction techniques are well established and referenced. Work is now being done to introduce them with a minimum penalty of cost, durability or other operating restrictions. In the author's view the next critical step will be for IMO and others to collaborate to introduce an on-board diagnostic system which is universally accepted and applied to ships. Only by this method would it be possible to ensure that low emissions engines continue to produce low emissions once the sea trials have been completed.
The opinions expressed in this paper are those of the author but he would like to thank the management of AVL List GmbH for permission to publish and to thank his colleagues for their co-operation.
 Erlach H., Chmela F., Cartellieri W, and Herzog P., "Pressure modulated injection and its effect on combustion and emissions on a HD diesel engine", SAE 952059
 Dexter S.G. and Kling W.H., "Medium speed engine design changes caused by international emissions regulations", ASME ICE Division Fall Conference, 1999
 Sowman C., "Independents Outlawed", the Motor Ship p17, Jan. 2000
 Schultz G., "Portable On-Board-Diagnostic (OBD) II/CAN Scan Tool", SAE 971126.