Baseline management of coatings and fuel consumption

The recent focus on hull and propeller performance monitoring as a means of allowing owners to justify their investment in a particular hull coating for fouling protection lends itself to analysis by the Baseline Management System. The total investment in the asset, to deliver the payload from point A to point B, is driven by the level of risk mitigation applied with risks considered in terms fitness for purpose, safety and the environment.

For example, an owner may decide that the ship needs the most economical engine, the most efficient hull form and the best available hull coating to mitigate the risk of excessive fuel consumption (fitness for purpose). However, in doing so, the return on investment (ROI) will be diminished due to the high initial investment. To offset this, the owner may decide to include only the most primitive bridge technology, exposing other risks such as groundings or collisions.

It is simply not possible for a ship to be designed, built and delivered to the owner in a manner that will offer any tangible assurance that it will achieve the best possible ROI unless the full scope of the operational risk profile (ORP) is understood. Only then can the total ownership cost (TOC) be defined. By managing trade offs between risk and TOC, owners can objectively manage their expected ROI. The Baseline Management System has been developed to provide a foundation for capturing the ORP, developing a TOC and then monitoring both the ORP and TOC throughout the life of the ship and therefore a means to capture the ROI.

The primary systems that present a risk to fuel costs are the hull and appendages, in presenting resistance to the ship moving through the water and the propulsion system in its efficiency in overcoming the resistance. Resistance has a number of components, and the only contribution that hull coatings play is in the frictional or viscous resistance.

By focusing on the hull coating, it is easy to miss the fact that the other components of resistance are by far the greater part. It could be better to produce a mid-range hull coating (in terms of price) and employ an effective cleaning cycle (both in water and in dry dock), and pay more attention to wave making resistance as driven by the hull form and the factors that contribute to the selection of the speed of operation.

The propulsion system will initially be decided by the owner’s capital investment in purchasing the best available systems. Once in service, the propulsion system will be maintained and monitored to ensure it is operating at its optimal efficiency. This involves consideration of propeller fouling protection and cleaning as this is a large component of the drive train efficiency. Hull coating, and maintaining a clean hull, is not a huge component when considering the overall effects on the fuel bill (the combined resistance minimisation and propulsion system efficiency).

To effectively monitor the hull and propulsion system efficiency requires detailed analysis of multiple areas of specialty including main engine efficiency, gearbox efficiency, propeller efficiency and hull efficiency. Critical to monitoring these is defining a known baseline for each upon handover of the vessel from builder to owner.

To monitor the efficiencies through life, the risk mitigation to fuel costs would be in an effective and specialist system such as the BMT Smart (services monitoring and analysis) system. Once all the factors are understood and there are defined baselines, it is possible to understand and monitor relative efficiencies by hand, but it would be better to employ a specialist software tool, and/or company to manage this on behalf of the owner.

The growth of marine organisms and the effects of fouling on hull and propeller efficiency is complex and the rate of fouling growth will depend on many factors including trade route and periods alongside. It is better to assess all risks to hull and propeller fouling and select a coating system based on this. Subsequently, the hull and propeller cleaning maintenance cycle can be defined around the coating.

There are a wide range of risks that form part of the operational risk profile for hull and propulsion efficiency. The Baseline Management System is employed as a method to consider all risks at the initial design stage, which can then be effectively managed throughout the design, build and trials, and then monitored through life, within the operational risk profile to build a TOC and provide the owner with a means for objective decision making regarding his ability to maximise ROI.