To look at the crowded waters of a major harbor today is to have spread before one’s eyes a panorama of the commerce epitomized in sea-carriage. For sea-carriage implies that the ships transporting the cargoes have been built to meet the specifications of some practical dreamer, some shipowner who had an idea of what kind of ship would fit his needs best. And just what kind of thoughts and dreams go through the disciplined mind of the businessman who has chosen the deep waters as the scene of his activity? The naval architect cannot do anything with the dream until the dream has become a plan, a set of specifications, a list of desiderata which the shipowner, out of his experience, has formulated. It does not vitiate our premise that there is a dream in the mind of every shipowner when we find thousands of standardized ships on the seaways of the world. Ask any of the owners of these standardized ships if they were pleased with the ships as they came off the building ways, and the odds are that none would say that he was unable to find some improvement for this standard ship which he is using. Every ship owner has a dream of the ideal ship.
It is a dream based on reality, on the desperately hard work of finding cargoes, on the bed rock of competition with other eager and shrewd shipowners from the ends of the earth, on a knowledge of ports, and cargoes, and working habits; on packaging, and statistical trends, and on the imponderables of international commerce. It is the dream of a ship designed to meet the specific needs of the particular trade in which she will be employed, a dream-ship which embodies every improvement, every desire which would make her perfect.
Perhaps the shipowner considers as of paramount importance the evaluation of the competition which he can expect in his particular trade route during the anticipated life of his new ship. Not only must the owner determine how best to meet present competition, but he must look ahead ten or twenty years to visualize what effect competition will have on his ship. It is perilously easy to order a ship which meets the needs of the moment but which may be economically obsolete long before the vessel is mechanically worn out. The magnitude of this decision may be appreciated when the present-day cost of ship construction is taken into account. Literally millions of dollars must be invested in the vessel which management determines to be competitively desirable. This evaluation of competition is made by the traffic manager, who studies the trends of the trade in which his company is engaged and forecasts the direction in which those trends will move in the future. This analysis is known as a traffic study and may be defined as a forecast of future business trends, based on past experience and present practice. It is an intensely practical study, and, on the resulting recommendations, the shipowner will invest millions of dollars. There is, therefore, no margin for error.
Logically, the economics of ship design commences with the traffic study. The traffic manager ascertains the speed of existing ships, the nature and quantity of cargoes moving on the specific trade route, and the demands of the shipping public. Above all, he must find out what the shippers want—are they satisfied with present shipping services and are they likely to be satisfied during the next quarter century with substantially the same type of service? If the answers are in the affirmative—and rarely will this be the case—the new ship may be a replica of ships already in service, with perhaps a few modifications in the direction of improved marine engineering practice. If the answers are in the negative, then the traffic manager must canvass his major shippers for their opinions as to anticipated developments in their business which might call for special adaptations in the new ship’s design. His own knowledge of the trade, with its variations in quantity and nature of cargoes offered, and his experience in meeting the transportation needs of his shippers, guides the traffic manager in his evaluation of these data.
The existing services are similarly studied. How do the competing ships compare with the traffic manager’s present fleet in speed, in carrying capacity, in specialized cargo- stowage spaces, in flexibility, in age, and in convenience of operation? What proportion of the current trade is carried by competitors, and what articles are, by preference, shipped on competing lines, because of superior facilities in the vessels of those lines? How do the existing ships measure up against the expectations of trade development? How should the new ship be designed to overcome the advantages enjoyed by competing craft and to meet the anticipated needs of the trade?
Last, and most important to the directors of the shipowning company, how much can the company afford to pay for the new ship? In other words, how much will the ship earn each year, and on what percentage of her capacity is that earning power based?
The answers to these questions come from the experience of the traffic manager, from his accumulated knowledge of the vagaries of the trade, from his appreciation of the unscientific, empirical, competitive nature of freight rates, and from his judgment as to the quantity of each cargo which will move.
Assume for a moment that the ship is to be of approximately ten thousand tons dead weight capacity. The traffic manager decides that the trade will support approximately five and a half to six thousand tons of cargo per ship for the year-round average loading, with peaks rising to almost nine thousand tons during three months each year, and valleys dropping down to about four thousand tons during four months each year. The average capacity for purposes of computing ship earnings is based on 60% of deadweight capacity. If cargo revenues are estimated at forty dollars a ton, the average revenue per voyage would be $240,000, and with four trips a year gross income would be nearly one million dollars.
The traffic manager’s job is finished when he submits his findings of fact, his conclusions, and his recommendations. The board of directors knows now approximately what cargo will be carried, and what the gross earnings of the ship will be. Next, the operations department is called upon to study these recommendations and to formulate a detailed set of estimates of the ship’s probable operating expenses. Again, experience and knowledge are major factors in determining how much it will cost to load and discharge the cargoes, to run the ship at the desired speed, and to maintain the vessel in accordance with company standards. The expense of crew and food, of tugs and pilots, of agents and dockages, must all be determined in order to anticipate the actual cost of ship operation, so that the profit on the vessel may be computed with reasonable accuracy. The profit, of course, ultimately determines the purchase price of the ship.
The final figure, which the directors must know, is determined by conference with the heads of the traffic and operating departments. Since the cost of the ship is limited by what the ship can earn, the margin between revenue and expenditure is a vital consideration. Should it appear that the margin is $250,000 per year, the maximum cost of the ship could be twenty times the annual margin, or $5,000,000. Inasmuch as this would absorb every cent of so-called profit, the directors probably would decide that the most they could afford to invest in the new ship would be three and a half to four million dollars. Thus it may be said that the ship’s cost is limited by the profit which theoretically may be earned in the normal course of the vessel’s employment. The more nearly the ship’s design tits the need of her trade, the greater is the likelihood that her costs will be economically within the capacity of the trade.
For example, a tramp vessel must be built with very careful regard for the expense of initial construction and for subsequent operation. The reasons for this “penny-pinching” procedure are found in the nature of the trade—there is the fiercest kind of international competition to meet, the cargoes carried are of low-revenue types, and the employment is uncertain at best. Every ton of additional—and hence to the owner, unnecessary—fittings above the bare minimum required to operate the ship represents a potential reduction in the ship’s carrying capacity. Every dollar spent for ship construction must be paid for out of the often- precarious earnings of the vessel. Every pound of fuel burned must be purchased out of cargo freights. Hence it has developed that tramp ships are the simplest ships in their design, have the least elaborate fittings, and the most rugged, inexpensive types of power plants. Since their employment is world-wide and their cargoes comprehend virtually all commodities which can be moved in bulk, tramp ships have great similarity of design, but cannot be considered to be designed particularly for any one trade, if by “one trade” is meant the transportation of one commodity or the employment of the ship in one specific trade route.
It is an interesting commentary upon the problem of the economies of tramp ship design that tramps of 1955 are built with the expectation that they will spend part of their lives as temporary members of liner service companies’ fleets. The owners hope thus to earn sufficient premium in charter rates to offset the higher cost of the increased speed and superior cargo gear. Consequently, the mid-century tramps are vessels with speeds up to fourteen knots, and some even have accommodations for as many as twelve passengers. Many of these new tramps already have been chartered by the liner- service companies for at least one voyage.
The cargo-liner, built as she is to serve a particular trade, equates a different aspect of the cost factor. The employment of the ship is much more certain than in the case of the tramp, and consequently her earning capacity is more predictable. She must meet certain requirements, else her competitors will garner the bulk of the cargoes offered. The ship will have a larger crew, in most cases, and certainly will have more elaborate fittings and more complex cargo gear, and will have a speed somewhere between thirteen and twenty knots or more. She will have four to seven holds, and four to eight hatches, may have up to sixteen sets of cargo booms, and will cost at least five million dollars to build in an American shipyard.
Insofar as operational expenses are concerned, there are certain tangible results which arise from designing the ship to meet the needs of the trade. A major problem today is the cost of stevedoring. Hence a ship with excellent cargo-handling characteristics, though she costs more to construct, actually will save money for her owners by reason of her faster cargo-handling features. If her port time can be reduced, the ship is able to make more voyages, and hence earns a larger revenue.
The logical basis for adapting the ship’s design to fit the needs of the trade in which she will be employed is found in the increased efficiency and consequent lower cost of the ship’s operation. As a carrier specializes in a particular trade, he comes to see what special features of the ship’s design can be made more efficient and hence of greater value. Efficiency may be judged in terms of increasing the rapidity of cargo handling or in widening the range of the vessel’s capabilities for her particular trade. In either case, greater efficiency produces lower operating cost.
As an example of increasing cargo-handling speed, the design of the United Fruit Company’s Yaque and Fra Berlanga may be cited. Ship design related to the new mechanized banana-handling terminals has permitted the speed of discharge to be increased to 8,000 stems an hour, or about ten hours for 'a shipload.
An example of widening the range of the vessel’s capabilities is the provision of a 105- ton boom in the Clan Camming to permit her to handle heavy railroad rolling stock without dependence on port facilities. The Blue Funnel Line ships have unusually large tanks for the transportation of edible oils, which have become major components of the ships’ loads in recent years.
There are movements of cargo which either are so tremendous in point of tonnage, or so exacting in the nature of the care required in transit, that special designs have been evolved through the years in order that the most efficient and economical use may be made of the ships employed in these trades. A spectacular example of how the volume of a cargo effects the design of cargo ships is found in the Great Lakes, where the so-called “standard ore boat” has been developed to provide the required water transportation of millions of tons of iron ore from Lake Superior down to Lake Erie.
Limited by the depths of channels and by the lengths of lock-chambers, for many years the Great Lakes ships were about six hundred feet long with a draft of twenty- four feet. With the opening of the Mac- Arthur lock in 1944, the ships’ length-limits were raised to about 800 feet, but the draft remained the same. The trend today is toward ships about seven hundred feet long, with a carrying capacity of about 20,000 tons—a far cry from the early days of wooden hulls and sails, into which cargo was lifted by a horse-drawn pulley.
Since rapid loading and discharge are paramount needs, the ports have been equipped with massive mechanical devices, so that the ships have no cargo-gear, their cargo- decks are unencumbered by structures, and every consideration of design is subordinated to the requirement of port speed.
A similar example of a specialized trade along the Atlantic Coast of the United States is supplied by the Seatrain Lines, whose ships transport general cargo of practically any sort, provided it is contained in a railroad car. Each ship is equipped with a full mile of railroad track, laid on four decks. Each deck having four sets of tracks to accommodate about six cars. Giant cranes are employed in ports of call to pick up the cars and* deposit them either on land tracks, or to lower them into the ship where they rest on track for the voyage to the port of discharge.
Another result of designing the vessel to meet the needs of her trade is that the ship’s size will be as nearly perfect as planning can assure. The traffic study will recommend what is considered to be the ship of “optimum size”—that is, a ship which is the largest vessel compatible with the needs of the trade, and which will produce the lowest unit cost of transportation. The optimum size is derived from considering the characteristics of the harbors to be visited, and the facilities of the ports to be served; the type of cargo and the volume thereof; the frequency of service which must be offered to satisfy customers; and the severity of the competition to be encountered. The optimum size of the vessel must meet all these requirements to permit of profitable operation throughout her lifetime.
In tramp trade, ships have grown in recent years to an average deadweight capacity of 9,500 tons and have a speed of about twelve knots. They may be about 450 feet long with a draft between 25 and 27 feet. Cargo ships of this standard size therefore can enter practically any harbor of commercial importance. It would appear that this size has been forced upon the shipowners as a result of major changes in the world’s economy, which now seems able to absorb greater quantities of the tramp-type cargoes. Iron ore, for example, is in great demand in the United States, and ships of less than 9,500 tons are not especially desired by the charterers since the unit cost per ton of cargo carried is usually higher in small ships than it is in large ones.
Tankers have grown since 1945 from an “average” of 15,000 tons deadweight to what is considered a “normal” size tanker of between 26,000 and 30,000 tons deadweight, with ever-larger ships being planned and built. There are two reasons underlying the growth of tanker-carrying capacities. One is the tremendous increase in the consumption of petroleum products. The other is that the sources of supply are relatively far from the consuming areas, and the time required for the voyage so great that the size of ships had to be increased if the demand for petroleum were to be met. Incidental to the increase in size, and one of the compelling reasons for this increase, has been the reduction in the transportation expense for each ton of cargo loaded. For comparison, the 16,500 ton T-2 tanker Esso Worcester may be measured against the 26,555 ton Esso Zurich. The Esso Worcester burns 325 barrels of fuel oil per day, steams at 14.6 knots, has a crew of 41 men, and carries 138,335 barrels of cargo. The Esso Zurich, on the other hand, burns 440 barrels of fuel oil per day, steams at 16 knots, has a crew of 56 men, and carries 226,377 barrels of cargo. The cost of the super-tanker is about seven million dollars, while the cost of the T-2 tanker today would be estimated at between four and a half and five million dollars.
The super-tanker may be approaching the limits of practicable size, since the vessels in excess of 30,000 tons have dimensions so great, and carrying capacity so enormous, that the flexibility which is a necessary attribute for most tankers is being lost, and the ships can be used only in a few trades. There is little question that they will justify themselves in these trades, but for worldwide service there are very real grounds for doubt.
In cargo-liners, the problems of optimum size are somewhat different, though definitely related. First of all, the quantity of cargo offered, and the regularity with which it is available, will determine the frequency with which ships will call at a port. Next, the individual ports must be studied to determine what size ship can be accommodated. Finally, the port facilities, such as berthing spaces, cargo transit sheds, and ability of the port to handle cargo, must also be appraised. When all the data have been assembled, the owner will be able to decide what size ship is best fitted to his needs.
It is obvious that the optimum size of a given ship is conditioned entirely by the needs of the trade in which she is employed. Whereas the super-tanker is excellent for the Persian Gulf-United States North Atlantic trade, she cannot be used to supply smaller ports such as Georgetown, South Carolina, or Morehead City, North Carolina. At the opposite extreme, the little feeder ships which ply the West Coast of Africa, collecting three to twenty ton lots of cargo, and bringing them to assembly points such as Monrovia and Takoradi for transshipment to ocean-going vessels, are far too small to be used economically in the coastwise trade of the United States or South America. The justification for the feeder ships lies in the numerous small offerings from undeveloped harbors, and the admitted impracticably of putting ships as big as the C-l and C-2 types into these harbors. In each case, the needs of the trade have had a profound effect upon the size of the ships employed therein.
To determine the optimum size of a vessel surely is one of the most difficult assignments which can be given to a steamship executive! It requires a vast knowledge of the trade for which the ship is being designed, and it entails a simultaneous appreciation of the competition which exists at present, and which may exist in the measurable future. It must be based on present operational practice and must forecast to some extent the operations of the future, not only on the owner’s part but on that of his competitors. It has to take into account the ports which are served now, and the effect which port improvements, planned or merely projected, will have. It entails consideration of the present habits of shippers, and also of possible changes in the packaging of cargoes— as, for example, the change from shipping boxed automobiles to shipping cars ready to drive away from the ship’s pier.
Through all these different avenues of thought, the shipowner must keep always clearly in view the need to devise a ship which will be big enough to meet his needs during the life of the ship, small enough to be economical to operate, and of the proper size for safe, efficient maneuvering and seakeeping.
It would be easy to select examples of ships which have been constructed to a particular dimension determined by her owners to be ideal for her trade. An excellent illustration of a ship which has been designed particularly for one trade is the Venore, of the Ore Steamship Company. Originally intended to ply between Cruz Grande, Chile, and Sparrows Point, Maryland, the ship was built to carry 22,600 tons of iron ore on a twenty-eight day turnaround. Her actual hull size was limited by the loading pier in Cruz Grande, but by a skillful combination of length and beam with draft, the desired increase of one-third over the capacity of her predecessors in the trade was achieved without great change in size. The essentially sound features of the design are manifest in the present operation of the ship, which requires either twelve day turnarounds to Venezuela, or twenty-four day voyages to Chile. This vessel, and her sisters, are the largest seagoing ore carriers in the world and have proved to be exceedingly economical and satisfactory in operation.
Another interesting example of a vessel especially designed and built to meet the needs of a particular trade is the new steamship Carl Schmedeman, built in England for the Reynolds Jamaica Mines, Ltd., to carry bauxite from Jamaica to Alabama and Texas ports. The first self-unloading bauxite carrier ever built, the Carl Schmedeman is able to discharge her 14,000-ton cargo in ten hours with her own conveyor-unloading system. Although the weight of this equipment reduces the net cargo considerably, the high speed of the ship at sea and the very short port turnaround-time combine to make this expensive transportation unit economical and efficient for the bauxite trade.
A final example from the cargo liner fleet of the United States is found in the Santa Barbara class of the Grace Line. Designed for the trade between New York and the West Coast of South America, the ship was intended to carry copper and zinc, hides and skins, coffee, sugar, and beans, and bananas and fresh fruits on the northbound voyage; southbound she loaded the typical exports of the United States—automobiles, agricultural machinery, cotton textiles, and manufactured goods of all varieties. She also was to have space for fifty passengers.
The efficiency of the design of this and sister ships is demonstrated by the fact that the ships operate on one of the most exacting schedules in the American merchant marine and survive the punishing routine with surprisingly little trouble. Double- rigged throughout, they are able to discharge or load cargoes from lighters on both sides of the ship—a most important provision for the open roadstead ports along the Peruvian and Chilean coasts. In large refrigerator spaces are carried the lucrative banana cargoes from Puna (Guayaquil), Ecuador, to Charleston, South Carolina, loaded through side-ports which permit handling the fruit without interfering with the other cargo. Express-type boilers, operated at maximum overload conditions, develop sufficient steam to cruise the ship at 16 knots regularly, although the hull and power-plant were designed originally for only 14| knots.
In all these cases, the owner has studied his trade, and has determined what particular features of design would give him the greatest economy in long-term operation.
Usually the ship intended for a special trade costs more to build and may carry less than the standard general-service tramp. As in the case of the Carl Schmedeman, the finer equipment and the closer adaptation of the design to the needs of the service result in a better and more economical vessel for the operator.
It would be a serious mistake to suppose that considerations of speed and carrying capacity—both deadweight and cubic—are not of prime importance in determining how best to design a cargo ship so that she will be an economically profitable unit. It is axiomatic that the larger and faster the ship, the greater the amount of cargo she will be able to carry from one port to another in a given period of time. But perhaps it is not quite so obvious that the carrying capacity of a ship is a factor related to the speed with which that vessel is handled in the ports of call. With poor cargo-handling characteristics, the finest and fastest ship will become an economic liability. And even with the finest possible cargo-handling characteristics, a ship sent to a port where stevedore efficiency is low will lose most of the benefits of the shipowner’s knowledge and the naval architect’s skill.
Memory goes back to the famous Atlantic Transport Liners Minnewaska and Minnetonka, which were built in 1923 as combination passenger-cargo liners. They carried only 368 passengers in one class and had ten cargo holds with a capacity of over a million cubic feet, with an estimated cargo deadweight of 20,000 tons. So huge a cargo capacity meant long port time and, according to my recollection, the cargo-handling characteristics were so woefully bad that the ships became “white elephants,” and were laid up when they were only ten years old, and sold for scrap in 1934. They cost about five million dollars each to build, and their scrap value was less than one hundred thousand dollars.
A further pertinent example, but in reverse, may be deduced from the Shaw-Savill Line, operators for decades in the combination cargo and passenger trade between England and Australia and New Zealand. The company will take delivery this year of a new ship which will carry passengers only. The reason for this limitation in a ship to be employed in the Antipodes trade is found in the economically insupportable delays in handling cargo in Australia. The directors of Shaw-Savill determined that they could make more trips per year, and consequently carry more revenue passengers, if they had only a day or two in port at each end of the voyage. The increased earnings from passengers are expected to offset the loss from the cargo excluded by the design of the ship, and full advantage is taken of the higher sea-speed of the ship.
Any further examination of typical ships in the different trade routes of the world would serve only to emphasize the principles which have been already touched upon. Essentially, the economic factors which have the greatest influence in the design of a ship, are three: competition, which must be evaluated correctly if the design is to prove economically justifiable throughout the ship’s life; size, which must be of optimum dimensions for her particular trade; and cost, which must be low enough to permit operation of the ship in bad times as well as in good limes. These factors underlie every aspect of the planning which the owner must complete before he is ready to invite the naval architect to convert the dream into reality. One factor may be given more consideration than another, depending upon circumstances, but before the Anal specifications are approved, they must all be taken into account. The goal of the shipowner is to formulate specifications for the best possible ship for the trade in which she will be employed. Although the complexity of the problems which must be solved by the shipowner may seem almost insurmountable, it is a tribute to his ability and the fundamental accuracy of his appraisal of the economic factors in ship design that his labors seldom result in other than success.