Shipping Wonders of the World

 © Shipping Wonders of the World 2016  |  Site Map  |  Contact Us  |

Building a Liner

When the architect of a vessel has finished his preliminary work the construction begins, entailing skill and labour that may endure from six months to six years

Building a liner

FROM SLIP TO SEA. The several stages by which a ship grows after the laying of the keel are diverse yet strictly chronological. After the keel plates have been laid the transverse members or “floors” are placed into position; then the frames are fastened to the tank sides, plates are hung in position and riveting of the hull begins. Different categories of workmen continually follow one another through the ship: carpenters, platers, riveters, caulkers, testers and painters, and then carpenters again for the launch. Out of this work of an army of men grows the trim form of the modern vessel. Above is a view of a liner’s stern being built up, with the hull taking shape.

THE first stage in the construction of a ship begins with the laying of the keel in the shipyard, a function which may or may not be accompanied by ceremony, according to the nature of the ship and her subsequent duties. It continues until the time of the launch.

The launch marks the end of stage one and the beginning of stage two - the vessel’s partial entry into the world, her emergence, as it were, from the embryo stage. Part two is concerned with the fitting-out, which is generally done in the basin alongside a large crane that lifts on board all kinds of items from heavy machinery down to small ventilating fans.

With the exception of the launch, stage three is the most important and anxious of all from the point of view of the naval architect. It is the trial trip, for then the ship must prove herself; she must make the speed which the design conditions have laid down; she must make it, furthermore, at a certain draught and with a certain specified fuel consumption in pounds per horsepower developed per hour, or in tons of fuel used per twenty-four hours. At this stage, too, she must demonstrate her ability to steer properly, to pull up from “full speed ahead” to “stop”, and to go from “full speed ahead” to “full speed astern” in a prescribed time. The launch is an anxious moment because, if calculations have gone wrong, the vessel may turn over or, alternatively, she may damage herself in running down the ways. Even so, she is not a completed ship and repairs may in certain circumstances be effected. On the trial trip, however, the vessel must be accepted or rejected by the owners. Thanks to the accuracy of modern ship construction the percentage of rejections per thousand ships built is almost negligible.

The fourth stage is concerned with the active life of the ship and may vary from a mere eight or ten years in the life of a hard-worked oil-tanker carrying petrol, to the twenty-five years of a tramp steamer. So great are the progress of modem machinery and the ability of the marine engineer to give more and more speed without corresponding increase in fuel consumption, that the life of a ship is tending to shorten not because the hull is worn out, but because it is economically obsolete. Therein today, in fact, lies the survival of shipbuilding as an industry; but that is another story, for we are here concerned with the construction of the ship, one of the most fascinating branches of modem engineering.

The final stage of which we can speak is the “death” of the ship. She then passes into the ship-breaker’s hands and suffers the reverse process. Ironically enough, in many instances the same tools are employed in the breaking; but, whereas building is a matter for precision and care in adjustment of parts, the breaking of ships is aimed rather at getting the largest pieces of metal consistent with the requirements of the furnaces into which these parts will ultimately be fed. Thus, the “dust to dust” of the human body is repeated all over again in the “iron to iron” of the death of a ship. We say purposely “iron to iron”, although the modem ship is entirely constructed of steel. The steel owes its origin to iron ore with suitable other ingredients and mixtures, of which the remnants of former floating palaces may form part.

The theoretically complete shipyard even to-day would have its own blast furnaces, steel works, rolling mills, foundries, forges and blacksmiths’ shops, in addition to the slipways, platers’ shops, carpenters’ shop, mould loft and various other departments which are necessary for the construction of the hull. These would be situated alongside one another.

Before the War of 1914-18 and until shortly afterwards there was one such shipyard in Great Britain - the Palmers Shipbuilding and Iron Company works on the River Tyne. In what some people are pleased to call the halcyon days of ship-building - before 1914 - it was possible for a piece of iron ore to come in at the quays on the Tyne, be transformed into pig-iron in the blast furnaces, and thence to be transferred to the big steel smelting furnaces. It would next, be transformed into an angle-bar or a plate, taken to the shipyard, measured, punched, sheared, hung up on the ship’s structure, riveted, caulked, painted and sent away to sea as a small part of the complete vessel.

Changing economic conditions have now ruled out all that. There are many shipbuilding companies in some way or another financially associated with steel companies. For this reason they buy the products of those steel companies, but few of them are self-contained in the sense that the Palmers Shipbuilding and Iron Company once was. Many of the steel castings of stem and stern frames that go to make up the complete hull are - again for financial reasons - imported into Great Britain from abroad. This, however, by way of introduction.

Our purpose here is to discuss the development of the ship from the laying of the keel to the delivery to the owners. We will omit for the moment any particular study of means by which the iron ore becomes pig-iron and the pig-iron presently becomes steel plates and shapes. The modem hull is composed of units of steel which may be called members. These members must be capable of withstanding all the stresses put upon them, due to rolling and pitching among waves and the thrust of the machinery working against the resistance offered to the vessel by the surrounding water.

The most primitive form of power-propelled cargo vessel was an ordinary open barge-like structure with machinery aft. This ship would merely have had cargo-carrying space and the means with which to propel it.

Importance of Building Berths

The modern ship is a development of this, and her open cargo-carrying space is now covered with a deck. Furthermore, the whole structure has been made weatherworthy; the holds in the deck giving access to the cargo have been covered in by hatchways; accommodation for crew, and sometimes for passengers, is fitted. Special types of construction have been introduced to meet special requirements and to deal with particular cargoes; but in the main to-day the world’s mercantile tonnage is composed of ships built on what is known as the transverse system of framing, with cellular watertight double bottoms.

Longitudinal strength in the vessel is secured partly by the rigidity of this double bottom and partly by the presence of longitudinal girders, which are known as side or deck stringers according to their position in the ship. Pillars are also used to support the deck structure and to aid in giving transverse rigidity to the hull.

Ships cannot be erected at random anywhere near water. They are built on ground which is specially prepared and which often has been used for the purpose for as many as upwards of one hundred years. The building berth is in some ways the most vital factor in the construction of a ship, for it has to take a continually increasing weight of hull structure.

More important still, it has to take the weight of the structure and support the hull members, the floors, frames, and the like, when they are in a relatively “plastic” state one to the other. The ground must therefore be solid, not liable to subside under weathering, or when heavy weights such as large castings are put into position on the structure. Any shifting of the ground not only means endless work in putting members back in their relative positions, but it may also entail serious distortion to the hull of the ship. For this reason, naval architects are always anxious when there is any postponement in the construction of a vessel that has been begun, particularly if the vessel’s hull is not completely plated, i.e. made rigid.

Building berths are generally piled in way of the blocks on which the hull structure is built, some piles being as much as 15-in in diameter and 40 ft in length. In many modern shipyards concrete building berths are used. This makes for cleanliness for the workmen. Furthermore, if the berth is roofed in, as it is in some yards, it permits of work proceeding without any interruption due to bad weather.

The berth naturally slopes down into the water. Piling is exceptionally heavy at this point because, during the launching of the ship, it is at the end of the berth that the concentration of weight is at a maximum, since the hull slides over the end of the launch-way.

Another essential feature for a good building berth is that it should be efficiently and adequately supplied with cranes for placing the various members of the ship’s structure in position during construction and for slinging up deck and side plates. How it is done is well shown in the accompanying illustrations.

Naturally, different countries and shipyards employ individual methods for the handling of material. Space does not here permit of a detailed discussion of the various arrangements, but from the illustrations some idea will be gathered of gantry cranes, cantilever cranes, closed-in berths and other methods of handling material.

The giant Cunard White Star liner Georgic in course of construction

A NEST OF STEEL. The illustration shows the giant Cunard White Star liner Georgic (27,759, tons) in course of construction, surrounded by cranes and scaffolding. The double bottom forms the backbone of the vessel, and the side frames or ribs are bound together with transverse beams placed in position after the frames have been arranged. One of these can be seen being lowered into place by the crane in the foreground. At this stage work on the deck plates has begun, and the transverse watertight divisions or bulkheads can clearly be seen. Many apertures are left - one, especially large, for the machinery. The engines, lifted on board item by item, are generally installed after the launching and erected from the bottom upwards.

It should be emphasized, however, that a good building berth and a good lay-out of auxiliary equipment round the berth, comprising machines for punching and shearing the plates, are all important factors in the building of a ship. In these days, when competition is so severe and when economic conditions make it essential for all owners to buy in the cheapest possible markets, the builder who possesses a good building berth, and suitable lay-out of equipment, is the one who financially survives. If a yard is old-fashioned and badly laid out, the path of the raw material to the building berth may be complicated by the presence of alien structures or material. This means that more men are needed and that greater time is taken, all of which add to the first cost of the vessel.

In a busy shipyard, the launching of one vessel is followed almost immediately by the laying of the keel for another. If we assume that a vessel has just been launched and that the berth is to be occupied by a new ship, we shall note that the first operation is to sort out the building blocks left in a rough-and-tumble state from the last launching and to place them in a position ready for receiving the new ship’s keel plates. The spectacular keel-laying which often takes place immediately after the launch of a particularly important vessel is mere showmanship. It is impossible to begin construction until the berth has been cleared.

Building blocks are made of baulks of timber, pitch-pine or fir, about 2 ft square and 4 ft 6-in in length. These are placed alternately in thwartship and fore-and-aft positions, being first of all arranged on pitch-pine planks about 6-in by-2 in by 8 feet running long-itudinally down the building berth. Two blocks are then placed athwart-ships at a distance apart from centre to centre, varying with the size of the ship - for a 7,000-tons cargo vessel the distance would be about 6 ft - then two more are arranged on top of these and at right angles to them, i.e. fore and aft. This is generally repeated with another “collection” of fore-and-aft and thwartship blocks; and then on top of these is a further layer of wood, and, finally, a tapered cap piece, shaped for insertion of wedges under the keel plates for purposes of “setting up” or lowering the plates themselves. This is the way in which the work is carried out in an average shipyard. Many of the modern shipyards with completely concrete berths use concrete blocks, but the principles employed are the same.

Ships are always built on a declivity to the berth, generally nine-sixteenths of an inch to the foot. But it is necessary first to arrange that the tops of all the building blocks from the forward end of the vessel to the aft end shall be at this declivity, i.e. that the line of the top of the caps shall slope to the horizontal at a rate of nine-sixteenths of an inch to the foot. When the blocks have been “levelled”, as it is called, in this way, the first of the flat plate keel units is taken and put down on the blocks, this having been prepared previously in the platers’ shed.

In a modern ocean-going cargo vessel the term keel is no more than a term, because the keel consists of a series of oblong plates placed on the blocks end to end, quite flat for about sixty per cent of the ship’s length, and bent up towards the fore and aft ends of the vessel, respectively, to take the stem bar and the stern frame. The keel plates, as with all other plates used in ship construction, have been ordered from the rolling mills by the shipyard drawing office to a rough size and shape, slightly larger than the size required. The plater has taken the plate from a “rack”, as it is called - where all plates are stacked vertically - and, working to the plan of the flat plate keel which he has received from the drawing office, has marked it for shearing, punching, planing and any other physical operations that may be necessary.

The complete set of keel plates is taken one by one to the building berth and each plate is lifted on to the blocks by the overhead cranes previously mentioned, being lowered into its proper place according to the sequence numbers. Each plate is joined to its neighbour by means of a butt strap - that is to say, the two ends of the plate are placed touching each other. Over them is placed another plate of the same width as the keel plate, but only long enough to cover the single, double or triple row of rivet holes at the end of each keel plate. This is known as a butt strap in contradistinction to a butt lap, by which latter term is meant that one end of the plate is lapped over another, the holes in the ends being common and riveted through.

Building a liner

BUILDING THE BACKBONE. The first plates of a ship are those forming the keel, which forms the basis of the hull. The vertical keel seen in this photograph is laid on the slipway which slopes towards the aft end of the vessel, and leads to the water into which she will eventually be launched. The illustration gives a clear idea of the ship’s double bottom, with its sub-divisions forming tanks for the storage of fresh water or fuel oil. Flanking the slipway are the giant gantries, equipped with cranes that lower the steel plates into position.

The keel plates are all “centred” on the blocks by the shipwrights, who make sure that the keel is straight, end for end, and that it is tolerably level, i.e. that there are no bumps throughout its length. Although the keel plates are now in position and bolted together, the whole keel is by no means rigid, but, as soon as it has been laid and levelled, it is riveted. The fore and aft angle bars for the vertical keel are then bolted into position. An angle bar is, as the name indicates, a long length of steel sectioned as a right angle. It is an excellent means of joining one member to another when holes are punched in either side of the angle.

After these angle bars have been placed in position a start is made with the placing in position of the vertical keel. This, with the flat plate keel, forms the backbone of the ship. It has other angle bars attached at the top, and vertical ones on either side. It is to these vertical angle bars that the floors, as they are called, are next attached. These are the vertical thwartship members which at the ship’s centre are the same depth as the height of the vertical keel. When plating has been placed underneath them, on top and along the sides, they form the ship’s double bottom.

This double bottom is one of the most important features of ship construction. It is a receptacle for water ballast, for liquid fuel, and for lubricating oil. It also acts as a powerful protection against damage, should the ship ground; for it means that even if the outer bottom, as it is called, is pierced, the vessel can still float on the inner bottom or tank tops. The floors are generally lightened by means of manholes which are punched into them. The manhole, as the name indicates, is a hole made in the plate, of flat oval section, and generally of sufficient dimensions to allow a man of ordinary size to crawl through. In addition to lightening the plate, the manhole also has the effect of making the tank capable of carrying liquid. Where it is desired to complete a tank, then the floors are solid, i.e. they have no manholes in them.

Our “members” now comprise a flat plate keel, vertical keel and floors. These floors have to be kept at the right distance, the one from the other, by means of other plates which are called inter-costals (i.e. “between the ribs”). They are so called because they extend only from one floor to the next. They contribute to the longitudinal strength of the ship and are placed in position after all the floors have been arranged. By this time, too, a start has been made with the outer bottom plating, and the tank top itself is nearly complete, as well as the plating at the tank side.

We now have the main fore and aft skeleton or backbone of the ship. It remains only to add what the old shipwrights knew as the ribs, i.e. the frames. These are made of one or another of various sections - bulb bar, angle bar, or even “Z” bar, the names being according to the sections, and the sections used according to the type of ship. These frames are attached to the tank side - which has small angle-bar brackets at intervals corresponding to the frame spacing of the ship - by means of large brackets that are generally known as knees.

Building a liner

AFTER THE BACKBONE has been built work is begun on the decks, side-plates and stem. This work progresses rapidly; this picture shows the hull six months after the backbone has been built, and the big castings for the stern are in position. Soon after the decks have been plated a start is made with the laying-down of the wood, and with the installation of the numerous deck fittings and of the auxiliary machinery. A start has been made with the superstructure, and the breakwater on the foredeck can be clearly seen.

The frames themselves, according to the type of ship, are either straight up and down or curved. In any event, they generally curve at the bilge of the ship, i.e. the rounded portion between the outer bottom and the ship’s side.

The most modern passenger-cargo and cargo ships have a distinctly flat outer bottom. Special fast vessels, such as destroyers or tugs or similar craft, have a sharp “rise of floor”, as it is called, i.e. the outer bottom rises at a sharp angle to the horizontal. The height of the frames varies according to the decks to which they run. They have, at various intervals, depending on the size of ship, other brackets that correspond to the position where the deck beams will come. If we think of the double bottom as the backbone of the ship and the frames as the ribs, the beams are the front of the body which bind the ribs together. They are placed in position after the frames have been arranged.

By this time a start has been made with placing the shell plating in position. Several of the deck plates have also been “laid”; but the plating of the deck is not complete, for many apertures have been left, the biggest one being for the machinery. Unless the ship is a tanker or some special vessel, this is placed amidships.

There are also other apertures corresponding to the cargo holds. The number of tiers of beams will depend upon the number of decks in the ship, eight or nine in the largest ships. If the vessel is a large passenger liner, a start will now have been made on the superstructure. As soon as some of the decks are plated it is even possible that a start will have been made with the laying of the wood and with the bedding down of items of deck auxiliary machinery such as the anchor windlass and winches.

Ready for the Launch

While all this constructional work has been going on, the big castings for the stem and stern frame will have been lifted in position and will now be incorporated in the hull itself. If the ship is a twin-screw vessel with a rounded stem - known as a cruiser stern - then the stern frame castings may be large and in certain instances rather complicated. The apertures for the twin screws are sometimes known, because of their appearance, as “spectacle frames”.

The different categories of workmen are continually following one another throughout the ship. The carpenters have been first, with the platers, to lay the keel and see that the preliminary members of the ship are in place. More platers have followed the carpenters, the riveters are following the platers, and the caulkers are following the riveters. The task of the riveters is to see that the plates are watertight. The caulkers are followed by gangs of testers, to test the tanks for water-tightness - to Lloyd’s or other Classification Society requirements - against so many feet head of water. This having been done, the compartments inside and out can be dried and will be ready for painting. By this time, too, the carpenters will be back on the job again, laying the launch-ways beneath the hull.

The launching of a ship is a highly specialized performance and will form the subject of another chapter. Suffice it to say, by now, however, that the vessel will be sufficiently riveted, caulked and made watertight for consideration to be given to her entry into the water. She slides down the ways into the water, floats at a very light draught successfully, is taken in hand by tugs, and towed alongside the fitting-out basin to receive first of all her machinery.

A CRITICAL MOMENT in the launch of a large liner

A CRITICAL MOMENT in the launch of a large liner, when the fore-part of the ship runs over the end of the greased launchways. After the launch has taken place, tugs take the ship and tow her alongside the fitting-out basin. Before her launch the ship must be adequately riveted, caulked and tested for water-tightness. The propellers and propeller shafts are also generally in position before the launch.

In many ships a start may already have been made on this when the ship is on the stocks. In Italy, where they launch into a tideless sea, they sometimes put their vessels into the water complete in every detail, and some ships have been known to be launched with their machinery ready for operation, and then to steam or motor away on their trial, trip complete. This, however, is the exception rather than the rule. Even should the boilers be in place - assuming the vessel to be a steamer - there will still be a great deal of outfitting to be done in the way of accommodation, cargo gear, masts, funnels, derricks, and so on. Generally the heavy machinery is lifted on board piece by piece, and is built up much in the same way as the hull itself has been built up, i.e. from the bottom. Until all this is in position and the engine-room is virtually complete, it is impossible to finish the upper portion of the hull and to lower the big engine-room hatch or top in place.

Once this has been done, the work on the equipment of the ship will have been pressed forward to such an extent that little remains to be done but the putting on board of the equipment. This includes boats, lifebelts and the like, and the finishing off of the joiner work in the cabins. After this the ship will be ready for the first of her many important ventures - the trial trip at sea. The time taken for all this constructional work varies. A small ship may be built in six months. A large vessel may take as long as six years. This is particularly true with mammoth transatlantic liners, for here considerations of policy and even of politics sometimes affect the construction as much as the plates and steel work. Considerable time also is taken in assembling the largest warships; but here the matter is complicated, because of the enormous armour-plates which have to be placed in position on the ship’s sides, and now, as a protection against aircraft, on the decks.

The ships that are constructed most quickly are generally excursion vessels intended for carrying passengers on coastal trips during the summer months.

Speed of Construction

Owners generally place their orders about the beginning of December, and expect to have delivery before the following Whitsun. A ship of this kind, which is anything up to 250 feet in length, normally requires seven or eight months for construction. Sometimes this period has to be compressed into five, because the owner does not place his contract exactly when he should.

The speed of construction on any vessel depends upon the arrangements followed in the shipyard. A works that is well laid out permits of the construction of such integral parts of a ship’s hull as the complete frame sections and bulkheads on the ground at the head of the slipway. Thus a complete ship can be prepared by the platers, the frame turners and the shipwrights in such a way that the erection is the swiftest part of the whole performance. This requires, however, careful organization and attention to detail. If the vessel is to be put together in a hurry, every part must be exactly correct, even to the position of rivet holes and so forth, and no time is available for the adjustments which are sometimes made during a more leisurely process of building.

The strangest process in the whole ship construction is that employed in certain craft for work in the tropics. For here the complete ship is built in a yard in Europe, bolted together, then dismantled, each part being carefully numbered, placed on board another vessel and shipped to its destination.

In some instances paddle-tugs, designed to float in a few inches of water, if necessary, on tropical rivers, have been partly taken to pieces and lifted on to the deck of a ship. The building of a modern vessel may, therefore, involve all kinds of problems besides the preparation of frames, plates and bulkheads.

The launch of the Strathmore on April 4 1935

ONE OF THE FINEST SIGHTS in the world, the launch of a great ocean-going liner. This picture shows the launch of the P. & O. liner Strathmore (24,000 tons), on April 4, 1935. Hydraulic machinery is used to start the ship off down the ways, and she is brought to rest by heavy chains - seen fixed to the hull - that retard the first swift plunge into the water. The launching cradle can also be seen. After the machinery has been placed on the seatings in the vessel’s hull, the cabin fittings, the electric installations and the innumerable accessories, many of which have been prepared beforehand, are taken on board to their allotted places.

[From part 2, published 6 February 1936]

You can read more on “Launching Ceremonies”, “The Shipbreaking Industry” and “RMS Strathmore” on this website.