The changing face of Naval architecture

In an interview with The Motor Ship, Nigel Gee described naval architecture as the second oldest profession in the world. He said “The modern science of naval architecture was established during the industrial revolution with the basic methodologies established for hull design, resistance prediction, propulsion, stability and structural strength. Little has changed since then and a practising naval architect in the 20th century needed to be a well-rounded engineer with the ability to apply physics and maths to the design of ever larger structures moving at higher speeds in the difficult interface between the atmosphere and the sea. Few, if any, aids existed to simplify the computations and drawings that the naval

architect has to make and a deep understanding of principles and an experienced ?feel? for the strength, durability and safety of the floating structures he designed were vital to the successful practitioner.”

High-tech design tools

“Following the advent of the computer and, more recently, a huge increase in processor speed, the ability of the naval architect to carry out ever more complex computations has increased perhaps a thousand fold. Computational fluid dynamics (CFD), sea keeping calculations, finite

element analysis (FEA) and a wealth of other software based tools enable the naval architect to complete complex in-depth analyses in a few weeks where previously years would have been needed. The necessity of this level of

analysis for some of today?s very large and complex vessels is beyond doubt, but the availability of low cost software for most of these analyses is questionable in the design of quite small and simple vessels.

There are two main drivers for this proliferation of analysis; the first is that the analysis is being undertaken simply because it is possible. There is a perception that by using these analysis tools an ?optimised? or ?better? vessel will result. Second is an increasing

concern on the part of operators and shipyards with possible litigation from shipowners and operators due to

vessel damage, loss of life, pollution, etc. This is leading many owners to specify an increased level of technical analysis in their build tenders with FEA, fatigue, noise and vibration analysis routinely being requested.

This trend means that the majority of naval architects have to become more specialised in sub-disciplines, and few are able to appreciate the total ship design problem. There is a danger that a design job becomes modular in nature and common sense solutions to overall design questions may be missed. It is interesting to note that the 1952 built transatlantic liner United States, capable of top speeds of around 40 knots, was designed

without any of these modern analysis tools. The same is true in the

aerospace industry, with rockets and

aircraft such as Concorde designed before the age of the desktop

computer.

There is a significant danger that naval architects will lose some of their capability to design since the whole process is becoming a little remote with reliance on software that uses processes and equations about which he may know little or nothing. One example of this is the use of the new harmonised damage stability regulations, which use probabilistic methods and are only realistically amenable to calculations using a software package. A naval architect will find it difficult to judge whether the resulting ?stability index? makes sense; whereas under the old deterministic methods, a visualisation of the ship in various flooded conditions was available, and realistic checks easily made. The problem is further compounded by the fact that different packages may give different results. It is of course true that the old deterministic methods are also much easier to solve using modern software, but at least the process could be clearly understood and the results judged. However, just because computers allow naval architects to use these probabilistic methods, does this mean it is desirable?”

Losing the art of design

“There is also a danger that naval architects will lose touch with the science (and perhaps the art) of the profession. The modern naval architect given two hull forms and all the information about their shape, coefficients, surface areas, etc and asked to compare them will probably reach for the nearest software package. Not so long ago, a naval architect could probably have made a judgment based on his extensive first-hand knowledge and experience. Should the profession be concerned that some of this ability may be lost? I think so.

The ever-upward trend in world trade, the desire for greater efficiency and eco-friendliness, requirements for speed and diversity in naval vessels caused by the changing nature of world warfare, all point to a significantly interesting period in naval architecture during the next decade. It would be a pity if opportunities for inspirational and innovative design are lost in a welter of analyses.

?A good design? is one that exceeds the owner?s expectations. Priorities will be that it meets his specification, is safe to operate, provides comfort and habitability for crew and passengers, meets environmental regulations and concerns, and meets the relevant regulations of class, international and national authorities. Complying with regulations is a question of diligence and will produce a vessel with features that comply with an international consensus, but is not necessarily a good design. Comfort and habitability is of increasing concern and is indicative of the realisation of the importance of quality of life to a seafarer to a successful operation. There is no doubt that good ship motions and well-planned ship accommodation are features of a good design. Increasing use of safety case analysis and failure mode and effect analysis in ship design significantly enhance ship safety and is surely a better approach than the previous prescriptive and sometimes arbitrary safety rules.

The most important aspect, and probably the most difficult, is to provide the ship owner with a vessel that exceeds his expectations as regards specification. His requirements will include speed, deadweight and fuel consumption and also sea kindliness, maintainability, manoeuvrability, and reliability. These are the difficult and challenging areas for the naval architect, and are also the areas where design skills may be lost due to increasing reliance on software based design.”

Changing design ethos

Simon Cormack of Simon Cormack Ltd in Glasgow told The Motor Ship: “I can confirm that the regulations are overwhelming the design process making it very difficult to incorporate the human element to any extent.”

He went on to say: “I believe that the design ethos has changed. A naval architect used to use his knowledge and skills to design the best vessel he could to be strong and seaworthy and then send it to a classification society who would check if the design met with their approval. It is now the case that a vessel is designed to the letter of the rules and it is the job of the naval architect to provide calculations and drawings to prove to the relevant class society that the design meets their requirements. This situation slows development in everyday naval architecture.

Effectively it is becoming more and more expensive to meet rules and surveys and it is therefore too much of a cost and risk for most owners to make any great advances in design. The developments in naval architecture therefore have been in providing a vessel with as much potential as possible within the constraints of regulations.”n