Today, ship designs are optimised around an estimate of normal conditions under which the vessel will operate, known as the "design point". But this does not necessarily represent the conditions the vessel will actually encounter.
“In that sense, it’s artificial,” says Tim Kent, technical director at Lloyd’s Register. “It’s a reference point used as part of the ship specification and contractual agreement between the owner and the builder. The ship has to achieve a performance level at this design point.”
Lloyd’s Register is working with at least one university to look at optimisation throughout the design life of the ship, rather than around a single point. Kent calls this a “new paradigm for ship design.”
“Rather than optimising around one point, technology could be applied to optimise the performance response as a flat plateau across the ship’s speed, sea or loading conditions. Couple this with engineered flexibility within the system, to keep the overall consumption parameters within the optimum range, and there is a huge profitability opportunity.
Makes more sense
“Then there’s a potentially different way of thinking about the design of the ship, its systems and how they’re controlled and operated. You’d need to think about how you were going to use the ship and integrate the conditions that the ship would see throughout its service life. Optimising according to that, rather than against a theoretical point at which it’s going to spend very little time, makes more sense,” says Kent.
According to Bernard Twomey, global head of electronic systems at Lloyd’s Register, the concept of operations for the actual ship is considered alongside the emerging technologies. “What we’re finding is that flexibility, enabled through some new technologies, helps meet a range of business needs for a particular client,” he says.
“Safety is a given but owners have a different perspective and set of requirements. It’s a challenge for Lloyd’s Register to understand those various operating modes. Are the systems going to be safe, dependable in all modes and, from a client’s perspective, are they going to meet their business needs?
“This is an even bigger challenge for ships that are actually sold because it’s a fixed technology, but do the new owners understand the limitations of the technology? Again, will it meet their business needs?” asks Twomey.
Kent adds, “A ship is a very complex arrangement of structure, materials, mechanical and electrical and other systems. How these all interact is quite important to understand if you’re going to be able to control all of those system components together in a way to optimise the performance.
Optimal speed for a business case
“The concept of operations is a fundamental part of that because it establishes the envelope under which that analysis is done. It’s really important that everyone understands that, because taking the systems beyond the original design assumptions means you’re taking them into the unknown in terms of their performance and interactions with others,” says Kent.
He confirms that while there is no such thing as an optimal speed for a vessel, there is an optimal speed for a business case.
“If you can understand the ship costs, the capital expenditure, the depreciation and the operating expense, you can understand the voyage costs in the context of fuel and other consumables. Then, beyond that, there are commercial costs, like maintaining the cost of inventory in transit rather than getting it to the end destination and sold on.
“Maybe the incremental fuel cost of traveling faster to get goods to their destination faster makes more sense in the overall business case. But from an overall consumption perspective, if you can tolerate a longer inventory time, it reduces the voyage cost.”
Kent says that if there is a need to operate at a slower design point, there will be a number of unintended consequences for the machinery operating at conditions it was not designed to operate at for a continuous period of time.
“Hence my suggestion that broader optimisation might be something for shipping,” he concludes. “It will be interesting to see how some of this research pans out.”
This article was originally printed in ABB Generations 2014.