6Sigma Marine (Pty) Ltd has its roots in Naval Architecture and Engineering Design.

With our studies from 4 top universities in England and Scotland with fellow engineers from Rolls Royce, DNVGL, Babcock, Lloyds, Shell, Technip and Sunseeker, we have built up a great network and group of friends around the world.

Our director practiced as a Naval Architect and Marine Engineer in Netherlands where from which we learned a great deal. Working at various interesting companies on different project, we gained extensive knowledge in a broad area of ship design. From luxury yacht designs for famous names such as Oceanco, Heesen, Director Shipyards and Hakvoort, to general shipbuilding best practices at companies like Damen Shipyards and a variety of offshore engineering companies such as Bluewater Energy Services.

This enabled us to bring great knowledge back to South Africa, and we can boast with being the only ship repair and conversions company with a fully capable Naval Architecture and Engineering Design department.

Business in South Africa is, however, very different than it is in Europe, with naval architecture knowledge spreading much wider than conventional services, as it requires much more understanding of in-situ production methods. The two disciplines could not be more interdependent.

6Sigma Engineering Services Department (follow the link to our engineering services) in earlier days was the technology partner for software companies such as ShipConstructor, CostFact, ShipWeight, Hydrocomp and Bentley, with interest in the latest technologies being a key driver to deliver world class work for our clients. This opened up the world to many contacts and points from which we could source pretty much any design, such as the sourcing of the design of one of the rarest and complex vessel in production called Project Hotel an Hydrographic Survey Vessels for the South African Navy.

Due to the market conditions and limited business opportunities in the business sector of technologies (software), it was decided to discontinue our outward drive for technology as a business, and rather focus on this internally to strengthen our position in the market as a front line Ship Repair and Conversion Company.


Naval Architecture concerns itself with:

  • The evaluation of the basic geometric and hydrostatic characteristics of ships.
  • The function of stability of ships in the design process.
  • An appreciation of the widely varying designs that are current in marine practice.
  • An awareness of how design requirements are generated.
  • An awareness of how physical constraints impinge to generate an optimal design solution.

Some great reading includes:
Basic Ship Theory by K.J. Rawson and E.C. Tupper who describe the discipline as below. Also see for those aspiring to become Naval Architects.


The need for a scientific approach was felt, first, because the art had proven to be inadequate to halt the disasters at sea or to guarantee the merchant that he or she was getting the best value for their money. Science has contributed significantly to alleviate these shortcomings, but it continues to require the injection of experience of successful practice. Science produces the correct basis for comparison of ships, but the exact value of the criteria which determines their performances must, as in other branches of engineering, be dictated continuously by previous successful practice, i.e. like most engineering, naval architecture is largely a comparative science. Where the scientifc tool is less precise than one could wish, it must be heavily overlaid with craft; where a precise tool is developed, the craft must be discarded. Because complex problems encourage dogma, and this has not always been easy.

The question, `Art or Science?’ is therefore loaded, since it presupposes a choice. Naval architecture is art and science.

Essencially, naval architecture is concerned with ship safety, ship performance and ship geometry, although these are not exclusive divisions.

In terms if ship safety, the main concern for a naval architect is to prevent a ship from capsizing in a seaway, and is also involved in the repair of damaged or maltreated ships. It is necessary to ensure that the ship is strong enough to prevent break up or fracture locally, which could lead to water breaching the hull. The crew must be assured that they have a good chance of survival if water breaches the hull of the ship by means of an accident or enemy action.

The performance of the ship is dictated by the needs of trade or war. The required amount of cargo must be carried to the destination which the owner specifies in the right condition and in the most economical manner; the warship must carry the maximum hitting power of the right sort and an efficient crew to the remote parts of the world. Size, tonnage, deadweight, endurance, speed, life, resistance, methods of propulsion, manoeuvrability and many other features must be matched to provide the right primary performance at the right cost. Over 90 per cent of the world’s trade is still carried by sea.

Ship geometry concerns the correct interrelation of compartments which the architect of a house considers on a smaller scale. In an aircraft carrier, the naval architect has 2000 rooms to relate, one with another, and must provide up to fifty different piping and ducting systems to all parts of the ship. It is necessary to provide comfort for the crew and facilities to enable each member to perform his or her correct function. The ship must load and unload in harbour with the utmost speed and possibly replenish at sea. The architecture of the ship must be to such a standard so that it can be economically built, and aesthetically pleasing.

The naval architect is being held increasingly responsible for ensuring that the environmental impact of the product is minimal in both normal operation and following any foreseeable accidents. There is a duty to the public at large for the safety of marine transport. In common with other professionals, the naval architect is expected to abide by a stringent code of conduct.

It is clear that naval architecture involves complex compromises of many of these features. The art is, perhaps, the blending of the right proportions. There are few other pursuits which draw on such a variety of sciences to blend them into an acceptable whole, and few pursuits as fascinating as naval architecture.


Ships are designed to meet the requirements of owners or of war, and their features are dictated by these requirements. The purpose of a merchant ship has been described as conveying passengers or cargo from one port to another in the most efficient manner. This was interpreted by the owners of Cutty Sark as the conveyance of relatively small quantities of tea in the shortest possible time, because this was what the tea market demanded at that time. The market might well have required twice the quantity of tea per voyage in a voyage of twice the length of time, when a fundamentally different design of ship would have resulted. The economics of any particular market have a profound effect on merchant ship design. Thus, the change in the oil market following the second world war resulted in the disappearance of the 12,000 tonf deadweight tankers and the appearance of the 400,000 tonf deadweight supertankers. The economics of the trading of the ship itself has an effect on its design; the desire, for example, of small tonnage (and therefore small harbour dues) with large cargo-carrying capacity brought about the three island and shelter deck ships where cargo could be stowed in spaces not counted towards the tonnage on which insurance rates and harbour dues were based. Such trends have not always been compatible with safety requirements, which now also vitally influences ship design. Specialized demands of trade have produced the great passenger liners and bulk carriers, the natural-gas carriers, the trawlers and many other interesting ships. Indeed, there is a trend towards more and more specialization in merchant ship design (see Chapter 16).

Specialization applies equally to warships. Essentially, the warship is designed to meet a country’s defence policy. Because the design and building of warships take several years, it is an advantage if a particular defence policy persists for at least ten years and the task of long term defence planning is an onerous and responsible one. The defence staff interprets the general government policy into the needs for meeting particular threats in particular parts of the world, and the scientists and technologists produce weapons for defensive and offensive use. The naval architect then designs ships to carry the weapons and the men to use them in the correct part of the world. Thus, nations like Britain and the USA with commitments on the other side of the world, would be expected to expend more of the available space in their ships on facilities for getting the weapons and crew in a satisfactory state to a remote, perhaps hot, area than a nation which expects to make short harrying excursions from its home ports. It is therefore important to regard the ship as a complete weapon system and weapon, and ship designers must work in the closest possible contact.

Nowhere was this more important than in the aircraft carrier. The type of aircraft carried so vitally affects an aircraft carrier that the ship is virtually designed around it; only by exceeding all the minimum demands of an aircraft and producing monster carriers, can any appreciable degree of flexibility be introduced. The guided missile destroyer resulted directly from the defence staff’s assessment of likely enemy aircraft and guided weapons and their concept of how and where they would be used; submarine design is profoundly affected by diving depth and weapon systems which are determined by offensive and defensive considerations. The invention of the torpedo led to the motor torpedo boat which in turn led to the torpedo boat destroyer; the submarine, as an alternative carrier of the torpedo, led to the design of the antisubmarine frigate; the missile carrying nuclear submarine led to the hunter killer nuclear submarine. Thus, the particular demand of war, as is natural, produces a particular warship.

Particular demands of the sea have resulted in many other interesting and important ships: the self-righting lifeboats, surface effect vessels, container ships, cargo drones, hydrofoil craft and a host of others. All are governed by the basic rules and tools of naval architecture which this book seeks to explore. Precision in the use of these tools must continue to be inspired by knowledge of sea disasters; Liberty ships of the second world war, the loss of the Royal George, the loss of HMS Captain, and the loss of the Vasa:

In 1628, the Vasa set out on a maiden voyage which lasted little more than two hours. She sank in good weather through capsizing while still in view of the people of Stockholm.

These disasters remain an influence upon design and operation, and has been tragically illustrated by the losses of the Herald of Free Enterprise and Estonia in the 1990s, while ferry losses continue at an alarming rate, often in nations which cannot afford the level of safety that they would like.



The authorities with the most profound influence on shipbuilding, merchant ship design and ship safety are the classification societies. Among the most dominant are Lloyd’s Register of Shipping, det Norske Veritas, the American Bureau of Shipping, Bureau Veritas, Registro Italiano, Germanische Lloyd and Nippon Kaiji Kyokai. These authorities meet to discuss standards under the auspices of the International Association of Classiffcation Societies (IACS).

It is odd that the two most inffuential bodies in the shipbuilding and shipping industries should both derive their names from the same owner of a coffee shop, Edward Lloyd, at the end of the seventeenth century, yet were two organizations.

Buy their book to learn more.

Follow us on: