Modern Tramp Design

In recent years the introduction of the cargo liner has dealt a heavy blow at tramp shipping, which was regarded as the backbone of the British Merchant Service. Technical improvements, however, promise partly to restore the tramp’s lost position in a rapidly changing shipping world

OUTWARD-BOUND FROM CAPETOWN. The Baron Haig was built for H. Hogarth and Sons, who have a large fleet of similar ships. A vessel of 3,391 tons gross, the Baron Haig is registered at Ardrossan Ayrshire. She has a length of 342 ft. 3 in. between perpendiculars, a beam of 48 ft. 7 in. and a depth of 22 ft. 8 in.

THE old-time seaman, steeped in the traditions of sail, would maintain that there was nothing in the job of designing a tramp steamer. One just built the hull by the mile, cut it off in lengths as required, inserted the engines and sealed up the ends, and that was all. Even the most hide-bound shellback, whose humour consisted largely of gross exaggeration, could not claim such a thing of the tramp of to-day, which has to be as carefully designed as any ship afloat, more carefully than many.

The demands of shippers are more exacting than they have ever been before and trade conditions more difficult. The life of such a ship under the British flag is approximately twenty years, and to look ahead for that period, considering the changes that have come about in the last two decades, is in itself a great problem. Guess work is tempting but risky ; if an owner is going to lay down between £8 and £10 a gross ton he must base the design of his ship on the most careful calculations possible.

The essence of tramp operation is that the ship must undertake to go into any reasonable port in the world, and many of these are in poor shape. There fore, no matter how pressing other considerations may be, it is always necessary to keep the draught of water light. Special features which would improve her on one route, and would certainly be embodied in a liner, would probably handicap the tramp on another route and are strictly debarred in favour of general features which will enable her to do reasonably well on the maximum number of routes. As the new ship, with her high cost, will have to compete with cheaply-run foreigners which have been bought second-hand, her machinery must be as economical as possible without incurring too high a first cost.

Every era brings its own problems, but at the present time the greatest is probably how to combat the cargo liner’s tendency to encroach on the field of the tramp, how to offer shippers and consignees as many of the liner’s advantages as possible without sacrificing any of her own. The wheel will doubtless turn in time, and. the tramp’s advantage of cheapness will be appreciated, but the modern tendency is for merchants to secure a quick turnover of their money by getting the smaller consignments delivered by the liners at frequent intervals. The essence of tramp shipping is that the ships deal only with full cargoes, which take some time to collect and to dispose of and which incur warehousing charges during either operation.

With modern conditions it is not surprising that the business of the tramp has diminished. The type which was regarded as the very backbone of the British Merchant Service, and the most valuable of all in wartime, has been greatly reduced in numbers since the beginning of the great slump in 1921. It is unlikely that tramp tonnage will ever be rebuilt to its old strength. The cargo liner has certainly come to stay, and for years to come the difficulty will be to keep the tramp type alive at all.

The authorities fully appreciate the danger, and when British policy was finally changed, and a measure of State aid given to shipping, it was the tramp side of the industry which received attention. By means of the loan scheme, which helped in new construction, provided two tons were scrapped for every one built, measures were taken to secure the building of new tramps of the latest type.

The most conspicuous post-war tendency in design has been the demand for a much bigger ship. Before 1914 the most popular size of tramp steamer was the “handy” size, somewhere between 4,000 and 5,000 tons deadweight, but now only a small number of such vessels are being built. Generally such ships are able to secure only low rates from the charterers, so they have mostly been sold to the cheaper flags to be run with their expenses cut to the bone. The new ships are generally built with a deadweight capacity of between 8,000 and 10,000 tons deadweight, 9,200 tons being a popular size. Vessels of this size have a gross tonnage of about 5,000.

British shipping has to meet foreign competition in various forms, but it is rather striking that the most dangerous rivals, and the ones which run their ships best, have a tendency to disregard tramps altogether because they cannot afford to maintain them under their regulations. On the other hand, the poorer merchant services, which can offer transport at the lowest prices because

of their poor standards, generally concentrate on tramps and have no liners at all.

Every British ship, tramp or liner, is run according to a scale of manning, victualling and the like that has been agreed upon between the owners and the men, but many foreign rivals have no such scales and many others, although they publish their agreed schedules, make no effort to keep to them.

Importance of Fuel Costs

Numerous instances can be quoted. In 1933 the Latvians bought a British tramp and immediately reduced her crew by 33 per cent. They had no difficulty in securing seamen at £1 a month owing to the severe unemployment in Latvia. When it is remembered that the National Maritime Board scale for a British A.B. is well over £8 a month it is easy to understand what British shipping has to face.

The cheaply-run foreigner has to face two handicaps which give his rivals, under certain foreign flags as well as under the Red Ensign some opportunity. By far the most important is the question of fuel, for, although the older vessel burns the cheapest coal that can be bought, she burns an immense amount of it. Occasionally the owners receive State aid in the form of a contribution

towards coal bills, but not as a rule. The other handicap is insurance, for knowledgeable underwriters in their own interests handicap a ship which is obviously decrepit. Unfortunately this handicap is limited by several factors. First there are many underwriters who are not knowledgeable; secondly, there are many who are not free agents because of collective agreements; and, thirdly, the owners of such tonnage insure as little as possible and the burden generally falls on the cargo owners only. Up-to-date British tramps have to aim at the lowest possible fuel consumption to make expenses approximately equal.

It is necessary, however, for the owner always to keep in mind a careful balance, for every hundred pounds which he spends on the new ship in this search for running economy is shown in her accounts all through her career in the shape of overhead expenses. As the effective life of a tramp is rarely more than twenty years under the British flag, the owner must reckon on a 5 per cent depreciation being within the reach of his accounts.

A TIMBER SHIP’S LIST may be due to many causes in addition to the heavy deck load, but nearly all timber carriers develop such a list when entering port. The Ingrid Thorden is a Swedish vessel of 1,885 tons gross. She has a length of 262 feet, a beam of 42 ft. 8 in. and a moulded depth of 20 ft. 6 in. She was built at Gothenburg in 1920.

Twenty years is a long time to look ahead and the problem of the tramp would be greatly simplified if it were possible to build a ship calculated to last five years at a quarter of the present cost. Considerations of safety forbid this being attempted, even if it were feasible.

The owner, therefore, ties up a lot of money in an up-to-date ship. With her he will certainly save fuel bills and probably be able to run her with a smaller crew than an older ship, thus saving wages and provisions ; but he has the added anxiety that if she has to be laid up for lack of business it will be a heavier loss to him than if she were an old vessel of low value. The tramp is by the nature of her work always liable to be laid up for indefinite periods. It is always a scramble for the cargo that is being offered and there are bound to be times when there is no business.

It is true that the owner then lays up his ship at the minimum of expense, and that the liner owner has to keep his running whether she is full or empty; but the tramp has not the protection of the liner conferences and only recently have minimum freights been established in a few trades. This is a new principle whose fate is still in the balance.

The most obvious means of reducing running expenses are by improvements in the engine-room, and as the tramp is, for the moment at least, normally steam-driven, the remarkable improvements which have been effected by steam engineers come under review. The most modern tramp steamers burn appreciably less than half, on service often in the region of one-third, the coal demanded by a ship of similar size before 1914, and fuel is always the biggest item.

The standard cargo ship engine for nearly forty years was the three-cylinder triple-expansion engine of the simplest possible type. This was partly to keep the first cost low and partly because the engine-room labour of tramps was not always to be trusted with anything intricate. It was only after the war of 1914-18 that the engineers, urged on by the wonderful progress made by the diesel, set to work and evolved various forms of steam engine which would have all the qualities of the old triple-expansion engine and be much more economical.

Costly Speed

There are any number of these devices on the market, some only a slight improvement and some revolutionary. Shipping has been so hard hit during the period when these improvements have been appearing on the market that the inventors have often been forced to prove their claims at their own expense. They have not hesitated to do so, either by installing their plant in ships of their own or else by fitting it on a “no cure no pay” principle, undertaking to make no charge if their claim for economy is not fully justified. No device, however ingenious, is an economy unless it raises the ratio of earning power to capital outlay. The faster tramp does not receive any higher rates than the slower one, although she may be able to get several more paid passages into the year. Also, speed may be costly, for while an increase from 10 to 12 knots is only 20 per cent, the faster ship costs roughly 70 per cent more to maintain.

To mention only a few modern devices out of many, the Lentz engine for ships of moderate power, using poppet valves and superheated steam, usually guarantees a fuel saving of from 20 to 25 per cent. In many ships an economy of 30 per cent has been obtained.

Such improved valves as Andrews and Cameron’s quadruple opening balanced slide valves save a lot of fuel. Turbo-compressors on the Gotaverken principle secure an economy of approximately 17 per cent.

A MAIERFORM BOW was fitted to the Kirnwood, a vessel of 3,817 tons gross belonging to the Joseph Constantine Steamship Line. Improvement in hull forms is a remarkable feature of the modern tramp The Kirnwood was built in 1928, and has a length of 389 ft. 7 in., a beam of 52 ft. 6 in. and a moulded depth of 24 ft. 3 in. She is registered at Middlesbrough, Yorkshire.

There are several forms of improved reciprocating engine, including the C.M.E.W. quadropod engine, Stephens’s and others. Great interest has been aroused by White’s engine, a combination of high-speed geared reciprocator and geared exhaust turbine. It obtains an economy in steam consumption of from 36 to 38 per cent over ordinary triple-expansion engines and it is claimed that the initial cost is no higher. White’s engine is 25 per cent lighter, and is stated to consume at least 30 per cent less fuel than the ordinary reciprocator.

In the ordinary exhaust turbine fitted to so many tramps the reciprocating engine is of ordinary weight and type, driving the shaft direct. Only the turbine is geared.

Despite all these improvements, there are authorities who believe that the most useful machinery for the tramp is the triple-expansion engine with the fewest possible additions and refinements. Similarly, the simplest boiler plant is advocated, although most steamers nowadays have superheaters either in their original design or else installed later.

The tramp tries to buy her fuel in the cheapest market, and when she does secure a favourable quotation she will take in as much as she possibly can without interfering with her carrying capacity. Since the war of 1914-18 many ships have been given dual firing, and are able to burn either coal or oil under their boilers so that advantage can be taken of whichever market is the cheaper.

The fitting of this appliance, which is not by any means elaborate, was encouraged by a number of strikes which made the supply of bunker coal uncertain, although the owners did not want to turn to oil exclusively with the possibility of its price going up. On many occasions the installation has been fully justified, but other owners have found that the oil-burning side is apt to deteriorate unless it is frequently used or given constant attention, which is difficult with a tramp’s small crew. In ships so fitted the coal bunkers are in their normal position, but most of the oil fuel is carried in the double bottom.

Improved Hull Forms

While all these improvements in the engine- and boiler- rooms tend to reduce the cost per horse-power exerted, it is an obvious economy to reduce the horsepower necessary to drive a ship through the water by improving the hull lines so that they reduce the friction without reducing the carrying capacity. The most up-to-date tramps embody as many improvements in their hull as in their machinery, and often more.

As the hull is always the most expensive item in a ship it is surprising that so little attention was devoted to tramp hulls for many years. The standard “cut off by the yard” form was considered to be good enough and to carry the maximum of cargo. Fine lines appeared only to be waste of hold

space, although if they reduced the necessary horse-power, and through it the fuel consumption, this waste could be made up from the bunker space which was saved. The liking for rectangular holds was partly due to the demands of the timber trade, but not entirely.

The idea of spending much money on tank experiments for every separate hull design was not considered. Such refinements were thought suitable for men-of-war or yachts, but a waste of money where a tramp was concerned. Nowadays all that has changed. It is fully realized that the hull can make as much difference to the ship’s accounts as the machinery, or more, and nearly every tramp of any size has her hull tested before it is laid down.

BUILT AT GLASGOW, the Bank Line motorship Olivebank, of 5,154 tons gross, dates from 1926. Her owners, Andrew Weir and Company, were also the owners of the well-known sailing ship Olivebank, a steel four masted barque of 2,795 tons gross, sold to Norwegian owners in 1922 and acquired by Gustaf Erikson in 1924. The motorship, which is mainly employed as a cargo liner, has a length of 420 ft. 5 in., a beam of 53 ft. 10 in. and a depth of 26 ft. 6 in.

This has produced a hull which is far more sightly than the fashion of twenty years before. Forward the sides are given a flare which helps to lift the ship over the waves. Aft, where the lines mean much more to speed than they do forward, there has been a conspicuous fining which shows its influence in the wake when the ship is under way. Every effort is made to keep the propeller submerged when the ship is in ballast instead of letting it project out of the water to half its diameter, making a great thrashing of white spray and losing power. These features and improvements are comparable to the minor gadgets and fittings which improve the efficiency and economy of an ordinary triple-expansion engine. For the parallel to the latest machinery improvements we must turn to the Isherwood arc-form hull, the Maier hull and several others which are revolutionary in design, produce the necessary economy but cost a certain amount of money.

Streamlining to reduce the effect of the air resistance makes little difference to a tramp, but below water it is different. Not only is the resistance of the hull and its excrescences to the water reduced as far as possible, but also many devices have been evolved to increase the efficiency of the propeller by improving the stream of water in which it works.

The pro-propeller stern post was designed after long tests to remove anything which detracted from the efficient working of the propeller. By tapering the stern post on one side it was found that a substantial improvement was effected in the efficiency of the screw. In an ordinary ship with a right-handed propeller the stern post is tapered on the port side at the top and on the starboard side at the bottom.

The rudder is shaped to continue this effect — at the top slightly inclined to starboard and at the bottom to port, although its axis is vertical. By this means designers contrived to avoid direct resistance and its consequent eddy and disturbance in which the propeller cannot do its best work.

Somewhat similar in principle is the wing fin, in the shape of a small curved bilge keel which diverts the run of the water so that it reaches the propeller virtually square, and not in an upward direction as it is made to do by the normal stern lines of a ship.

Streamlined Rudders

Another interesting feature of that kind is the Star contra-propeller which in its original form was a fixed propeller with six fixed blades attached to the rudder post just abaft the screw. Later the projecting side blades were abolished and only the two vertical blades were retained in line with the rudder post.

This is fitted in the space between the propeller and the stern post, with only a few inches of clearance, and acts as a guide which greatly reduces the turbulence of the water passing the rudder, reducing the percentage of slip (wasted effort by the screw) and improving steering.

Steering and the rudder can have much influence on the economy of a ship. Many miles can be added to the ship’s run in a single day if she is yawing madly instead of steering a straight course, and it has been established beyond doubt that the single plate rudder in use for so many years is wasteful in many ways. Far more efficient is a streamlined rudder. Balanced rudders, in which part or the surface is forward of the axis, demand less power in the steering engine and consequently less fuel. The Oertz rudder is popular in modern ships and is fitted in some of the largest liners. Its cross-section resembles that of a fish, and it is completely streamlined.

While all these innovations improve the efficiency of the hull they also have a tendency to force up its cost, but nowadays the builder saves all the money that he can by standardization, not only in the various fittings which he puts into the ship but also in the hull itself, saving much money on such things as templets and patterns.

Among other establishments, the Burntisland Shipyard, on the Firth of Forth, has become famous for its “Economy” type of cargo steamer which was evolved after a thorough investigation into the problems of efficient ship propulsion. It is not a standardized type but is built in many sizes, with particular features for particular trades, such as the London coal trade.

ONE OF THE MOOR LINE FLEET, the Queenmoor was built at South Shields, Co. Durham, on the River Tyne, in 1924. A vessel of 4,863 tons gross, she had a length of 405 feet between perpendiculars, a beam of 53 ft. 7 in. and a depth of 26 ft. 6 in.

Its principles are the most perfect possible streamline flow and the ideal inflow to the propeller. This reduces the fuel consumption, so that the ship carries more cargo, due to having smaller bunkers. The engine-room crew is reduced to the minimum and the owner has less trouble and expense, because of the absence of expensive gadgets which are likely to go wrong. The design claims an economy of about 30 per cent over previous standard tramp types.

Other shipyards have worked to the same end, and J. and C. Harrison, of London, were among the first tramp owners to get the full benefit. They ordered a large number of big ships when the shipbuilding slump was at its worst and the yards were willing to quote low prices.

These Harrison ships are not all sisters and, although their hulls are designed on the same general principles as the Burntisland “Economy” type ships, a good deal of money has been spent on special fittings.

Ever since the war of 1914-18 enthusiasts have been trying to secure the general adoption of the diesel engine for the tramp, pointing out its running economy which is so important in ships of that type. For a long time they failed, for, while the running economy was acknowledged, the difficulty of persuading skilled diesel engineers to endure the discomforts of a tramp, and many other disadvantages, were quoted against it.

Recently, however, there has been a big change of opinion, and the majority of the tramps built under the British “scrap-and-build” cheap loan system have been motor-driven. Doxford of Sunderland, the originators of the old turret deck ships, have put an immense amount of research work into the production of a really efficient motor tramp and have evolved a standardized type, of 9,200 tons deadweight, which has been adopted by a number of owners on the north-east coast.

The main factor of the success of these ships has been that the firm has produced a standardized diesel which is not only simple for management by an average crew, but is also exceedingly compact, allows for larger holds at the expense of machinery space, and is made light by the use of welding.

Better Quarters for Crews

This Doxford diesel engine has three cylinders with opposed pistons. The explosion between the upper and lower pistons forces them in opposite directions simultaneously. The engine develops 1,800 brake horse-power on service, which is sufficient for a trial speed of 11 knots, and a sea speed of rather more than 10 knots on about 6 tons of oil a day for all purposes.

The great improvements during the last few years have increased the problem of personnel. A technically trained man demands better quarters and living conditions than contented the older type. There are still many tramps afloat in which there is a good deal to be desired in the topgallant forecastle forward, separated from the working positions of the crew by a fore well-deck which is liable to be swept by big seas. Some of the tramps recently built leave nothing to be desired, and the crew’s quarters compare favourably with the accommodation for which passengers paid a good price until recently.

The motor tramp Peebles, for example, has separate rooms for day men and night men, so that nobody’s sleep is disturbed. There are separate mess-rooms for the seamen and petty officers, separate wash-places with hot and cold running water and shower-baths, carefully arranged ventilation and a drying-room for wet clothes.

In the years which immediately followed the war of 1914-18, the tramp market was flooded by a large number of ships which had been built by the Government to standardized design to counteract the German submarine blockade. These vessels are steadily disappearing, from the British list at least, and are being replaced by magnificent ships which bid fair to restore the tramping side to something of its old position in spite of the tremendous difficulties which the owners have to overcome.

A GREEK TRAMP STEAMER built by Doxford and Sons as the Penrose in 1903. When sold to her Greek owners she was renamed the Adelphotes and registered at Andros. This photograph shows her at Pin Mill, near Ipswich, Suffolk. Of 3,882 tons gross, she is 350 feet long, 49 ft. 1 in. in beam and 23 ft. 10 in. in depth. She is one of the few surviving “turret deck” ships once popular.

You can read more on “British Shipping”, “The Peebles” and “Progress of the Motorship” on this website.