How Wooden Ships Are Built E-Book

Harvey Cole Estep

• Herausgeber: Edizioni Savine
• Kategorie: Fachliteratur
• Sprache: Englisch
• Veröffentlichungsjahr: 2023

Beschreibung

The revival of wooden shipbuilding in the United States dates from the latter part of 1915. In April, 1917, at the time we declared war against Germany, over 150 large wooden vessels were under construction along our coasts, principally in New England, the South and the Pacific Northwest. With America’s entry into the war, the tonnage requirements of the entente allies were tremendously increased. It soon became evident that the United States would be called upon to construct an enormous armada of steel cargo carriers and in addition as many wooden vessels as could possibly be turned out. Subsequent events up to the spring of 1918 have served only to emphasize the problem. The universal cry is ships, ships—and yet more ships!
This revival of the art of wooden shipbuilding has brought with it an insistent demand for information on How Wooden Ships Are Built.
It is to assist in this important work of training that this book is offered.
Harvey Cole Estep (1918)

Leseprobe

How Wooden Ships Are Built

A Practical Treatise on Modern American Wooden Ship construction with a Supplement on Laying Off Wooden Vessels

By H. COLE ESTEP

Editor of The Marine Review

THE PENTON PUBLISHING COMPANY

Publisher of The Marine Review Cleveland, Ohio 1918

The revival of wooden shipbuilding in the United States dates from the latter part of 1915. In April, 1917, at the time we declared war against Germany, over 150 large wooden vessels were under construction along our coasts, principally in New England, the South and the Pacific Northwest. With America’s entry into the war, the tonnage requirements of the entente allies were tremendously increased. It soon became evident that the United States would be called upon to construct an enormous armada of steel cargo carriers and in addition as many wooden vessels as could possibly be turned out. Subsequent events up to the spring of 1918 have served only to emphasize the problem. The universal cry is ships, ships—and yet more ships! The necessity, under these conditions, for a large fleet of wooden vessels is no longer disputed, and wooden shipbuilding flourishes all around our far-flung coast line from Maine to Washington.

This revival of the art of wooden shipbuilding has brought with it an insistent demand for information on how wooden ships are built. Compared with the needs of today, the number of expert wooden shipbuilders in the United States at the outbreak of our war with Germany constituted scarcely more than a corporal’s guard. Thousands of new men have been inducted into the business. These men must be trained. They must be taught the “know how”.

It is to assist in this important work of training that this book is offered. In other words, the book has been prepared to meet a war emergency and it is hoped the information it contains is of practical value.

Most of the material appeared originally in a series of articles published in The Marine Review between June, 1917, and March, 1918. The entire text, however, has been carefully revised and brought down to date.

The illustrations, which the publisher believes form perhaps the most valuable feature of the volume, have been carefully selected. Over 150 of the original photographs were made personally by the author expressly for this work. They were taken with the sole purpose of showing clearly and accurately how modern wooden ships actually are constructed. The aim in every case was to present important details of construction rather than general views. To obtain the photographs and collect the material for this work the author traveled extensively and visited nearly all of the important wooden shipyards in the United States.

An effort has been made to produce a book that is practical and illustrative and one that also reflects current American practice accurately.

The mathematical theory of ship design and other details which come more within the province of the naval architect than the shipbuilder have been omitted. As a supplement, however, two chapters on laying down wooden ships from the treatise of the late Samuel J. P. Thearle have been added. Acknowledgment is made to John W. Perrin, librarian, Case Library, Cleveland, for the opportunity to reprint portions of this rare work published originally by William Collins Sons & Co., London. While Professor Thearle deals with laying down British ships of the line, the underlying principles of which he treats are unchangeable and it is doubtful if any present-day author could present the subject more lucidly.

The publisher and author wish to express their appreciation of the generous assistance they received from the leading wooden shipbuilders of the country, without whose aid this work would have been impossible. By permitting full access to their plants and by whole-hearted co-operation in furnishing valuable data, detailed drawings, etc., they have set an example of patriotism and broadmindedness that many lines of business could emulate.

For particular services, advice and assistance the author wishes specially to acknowledge his indebtedness to Capt. James Griffiths and Stanley A. Griffiths, Winslow Marine Railway & Shipbuilding Co., Seattle; S. H. Hedges, Washington Shipping Corp., Seattle; M. R. Ward, Grays Harbor Shipbuilding Co., Aberdeen, Wash.; F. A. Ballin, Supple-Ballin Shipbuilding Corp., Portland, Oreg.; O. P. M. Goss, West Coast Lumberman’s association, Seattle; Frank M. Stetson, Stetson Machine Works, Seattle; Martin C. Erismann, naval architect, Houston, Texas; R. Lawrence Smith, New York, and G. W. Hinckley, Brunswick Marine Construction Co., Brunswick, Ga.

How Wooden Are Built

CHAPTER I

Typical Methods of Construction

WOODEN shipbuilding was a lost art which the gods of war decreed must be revived. When the European war broke out in 1914, there were over forty-six and a half million tons of merchant steamers afloat. Most of them were steel cargo vessels suitable for overseas trade. As nearly as can be estimated, the submarines accounted for nearly one-fifth of this tonnage up to Jan. 1, 1918. A tremendous revival of shipbuilding the world over has been the natural reaction to this situation.

Soon after the United States declared war it became evident that it would be necessary to construct a large fleet of wooden vessels to supplement the enormous tonnage of steel ships which the emergencies of war demanded. Although the original chimera of a fleet of a thousand or more wooden cargo carriers loosed on the seas to bear the brunt of the submarine attack has properly faded from the public mind, the wooden ship remains an exceedingly tangible factor in our shipbuilding program.

At the end of 1917 the United States Emergency Fleet corporation had let contracts for 379 wooden steamships with an aggregate deadweight tonnage of 1,344,900. In addition 58 composite vessels had been contracted for with an aggregate tonnage of 207,000.

If properly constructed, these vessels may be used for transatlantic service. At all events they will be suitable for many coastwise purposes, thus releasing valuable steel steamers for work overseas.

The wooden ship is a necessity in the present emergency. The ranks of "the little cargo boats that sail the wet seas roun’ ” have been seriously thinned by the unholy submarine warfare of the German empire. The dingy tramps of the ocean lanes, England's and America’s pride, are threatened, and unlike the situation described by Kipling in 1894, the man-o’-war has found himself unable “to up an’ fight for them” with complete success, although tremendous forward strides in the offensive against the submarines were made during 1917.

In the meantime, while a method of completely exterminating the German pest is being evolved, and long after the last one has been swept from the seas, shipbuilders everywhere will be obliged to proceed at top speed to provide vessels sorely needed by the world’s commerce. When trade revives after the war, the demands for tonnage will be so great that it now appears both wooden and steel shipbuilders are assured a long period of prosperity and profitable activity.

All sensible men recognize the merits of the steel ship. Its superior effectiveness in many directions is readily acknowledged. But we are now face to face with a great national emergency in meeting which the wooden vessel has a definite function to perform.

Therefore, mallets and saws are busy throughout the great length of our seaboard from Maine to Texas and from California to Washington building a host of wooden vessels. As a result of this activity there has grown up a demand for information of a practical character on wooden shipbuilding which it is the purpose of this book to supply.

How large may wooden vessels be built? This is one of the first questions that arises in considering the construction of wooden cargo carriers, for the economies of large units are thoroughly appreciated throughout the maritime world. In the heydey of the wooden ship, in England and Europe about 1850, very few vessels larger than 2000 tons were constructed, and practically none were over 40 feet beam. Their length was usually about 200 feet. Their tonnage was limited by the fact that the

naturally crooked oak timbers used for the frames grew only in limited sizes. The same limitations existed in regard to long timbers, such as keels, keelsons, strakes, clamps, shelves and planks, which had to be built up and well scarfed, locked, hooked and bolted to make up for lack of large size material. It remained for the Pacific coast of the United States with its boundless supply of timbers of the largest sizes, to finally demonstrate that wooden vessels of 3000 to 3500 or oven 4000 tons deadweight capacity are practicable. There is, however, a difference of opinion among architects as to the extent to which the largest hulls should be reinforced with steel. In 1917, two wooden vessels, 308 feet long, 285 feet keel, with a deadweight capacity of 4300 tons, not including 2500 barrels of oil fuel for diesel engines, were built on the north Pacific coast. These vessels, which are so reinforced with steel as to fall almost in the composite classification, have been given the highest rating by both American and British classification societies. Conservative opinion leans to the view that vessels without steel reinforcement should not be built over 260 or 270 feet in length. For any vessels over 200 feet arch strapping, at least, seems desirable.

As far as the supply of lumber for wooden ship construction is concerned, there is little to fear. The estimated total supply of merchantable timber in the United States is placed at the stupendous figure 2,500,000,000,000 feet board measure—over two-thousand billion feet. Canada, in addition has 80,000,000,000 feet. Russia has even more timber reserves than the United States. A large portion of the shipbuilding timber in this country is in the Pacific northwest, the state of Washington alone having over 11,700 square miles of standing timber, exclusive of national forest reserves. In the south, along the gulf and southern Atlantic coasts, there are almost equally important timber reserves, and on account of its superior strength, southern pine is prized for shipbuilding, although it does not grow as large as western fir. Also, in spite of 300 years of exploitation, the forests of New England still contain vast quantities of ship timber of unusually satisfactory character.

In fact, New England is one of the two sections of the country in which wooden ship building maintained a continuous existence through the lean years, 1880 to 1916. The north Pacific coast is the only other region where the art of building wooden vessels failed of complete extinction during the period just mentioned. It is from the traditions of both of these important sections, separated by 3,000 miles of continent, that the revived art and the new literature of wooden ship building must be drawn.

Power for Wooden Ships

Wooden hulls are best adapted to sail power, but for obvious reasons such a method of propulsion cannot be depended upon in modern times, except for certain special trades. In the war zones, sailing ships are under a severe handicap because of their high visibility. Some form of mechanical propulsion, therefore, is desirable for practically all of the wooden vessels now under construction or to be built during the next 24 months. Virtually only three types of power present themselves, oil engines of the pure or semi-diesel type, reciprocating steam engines and steam turbines.

The advantages of the oil engine in fuel economy, increased cargo space, low visibility, etc., are well known, and for these reasons a large number of the wooden vessels built in 1916-17 were fitted with internal combustion motors, usually working twin screws. Undoubtedly, this arrangement is one of the most satisfactory that could be devised for large wooden merchant ships. But it has been shown there are not enough skilled oil engine builders in the country to supply the demand at the present time. Therefore recourse is had to steam. The question of obtaining enough skilled engineers also enters into this problem.

For a full-powered ship, the concensus of opinion seems to be that about 1,500 horsepower is necessary for propelling a 3,000-ton vessel. In spite of the advantages of the oil engine, steam is not without its advocates, especially among those who point out the space saving possibilities of the turbine.

Types of Hull Construction

Compared with steel vessels, wooden ships are weak in both longitudinal and transverse directions, although their greatest structural failings appear to be in longitudinal planes. Large wooden hulls are susceptible to both hogging and sagging. In the former case, the deck bends con-vexly, the ends becoming lower than the midship section; in the case of sagging, the deck bends concavely and the sheer is exaggerated. Also, in a seaway, some wooden hulls are sprung up from the bottom, causing the decks to bulge. These weaknesses are largely due to the rectangular construction of wooden ships, in which the fastenings are depended upon almost exclusively for stiffness.

In the nature of things, it is impossible to fasten the members of a wooden vessel together as stiffly as those of a steel ship, but by proper design and construction a great deal of the weakness inherent in wooden hulls may be overcome. If we consider a ship as a beam and resort to the language of the engineer for a moment, we find that the greatest strength should be concentrated as far from the neutral axis (approximately the center of the load waterline plane) as possible; also, the sides of the vessel should he designee to withstand permanent vertical and longitudinal stresses; and the connections between the flange and web members (decks and sides) should be as rigid as possible.

Typical Wooden Vessels

The accompanying cross sections of typical wooden ships show how designers in various parts of the world and at different times have attempted to meet these conditions.

Fig. 3 shows the cross section of an English sailing ship built to rigid specifications about 1850. This vessel was 30 feet beam and about 180 feet in length. A detail of the keel construction is shown in Fig. 2. This ship had considerably more deadrise than a modern cargo carrier, that is her bottom was much less flat than is now customary, and this rounded construction added tremendously to her strength. In addition, she had two decks, the lower deck beams being 6 1/2 x 8 inches and the main

deck beams 9 x 10 inches. Finally, she was very carefully and painstakingly fitted together in order to give the utmost stiffness and permanency to the hull structure.

Fig. 5 shows a cross section of a modern Pacific coast lumber vessel of the conventional type. It forms an interesting comparison with Fig. 3. This ship is 48 feet beam and about 275 feet in length. Her floors are 18 inches deep, compared with 9 1/2 inches in the English ship shown in Fig. 3. But in the latter case, natural bent oak was used for the frames and in the modern Pacific coast boat, sawn fir. Some architects think that the depth of the frames in the vessel shown in Fig. 5 is too small. This illustration, however, shows very clearly the characteristics of customary American construction. The feature of the design is the large number of keelsons, nine in all, running from stem to stern like a small mountain range. Fig. 5 also indicates the large size of the planking and ceiling timbers.

A more advanced form of construction, designed by Fred A. Ballin, naval architect, Portland, Ore., is shown in Fig. 4. In this case the necessity for a large number of keelsons is obviated, in the designer’s opinion, by the use of deep floors

and deck beams. Care also is taken in the disposal of the knees, ceiling and planking.

One of the most successful forms of steel reinforcement for wood vessels is shown in Fig. 7, illustrating a method of construction patented by Frank E. Kirby, of Detroit, one of the most famous naval architects on the Great Lakes, where a large number of unusually staunch wooden vessels were built in the era before the steel freighter. According to Mr. Kirby’s patent, the topsides are strengthened by means of a steel sheer plate, to which a deck stringer plate is connected with a strong angle. The deck stringer rests directly on the top of the top timbers of the frames and the iron straps running diagonally around the hull are fastened to the sheer plate. This is somewhat similar to the method of reinforcement adopted for the new wooden steamers being built for the government under the auspices of the United States Shipping Board Emergency Fleet Corporation, except that in the case of the government boats the deck stringer construction is lighter.

CHAPTER II

Strength and Characteristics of Ship Timbers

BEFORE any attempt is made to lay down or build a wooden ship, the architect, yard superintendent and others responsible for the success of the proposed vessel, should acquire a fundamental knowledge of the physical characteristics and strength of the timbers that will be used in the construction of the hull. An investigation also should be made into the different methods of fastening timbers together in shipbuilding and of the efficiency of such fastenings. In other words, a little knowledge of the elements of structural engineering is as essential to the shipbuilder as it is to the building contractor or bridge erector.

For an intelligent and thorough grasp of the subject it is necessary, in fact, to start with the lumber industry, which bears the same relation to wooden shipbuilding as iron-ore mining does to the manufacture of steel. In this chapter, therefore, a few facts will be presented regarding the production of lumber in the United States, together with data on the physical characteristics and strength of various species of ship timbers.

In the preceding chapter, figures covering the supply of merchantable timber in the United States and Canada were presented. To give an idea of the ability of lumber manufacturers to furnish ship timbers in quantity, it may be stated that the United States forest service has estimated the lumber production of the United States in 1915, the latest year for which figures are available, at 37,013,294,000 board feet. During 1915 there were 29,941 mills in operation. The details of the lumber cut of 1915, showing the number of mills and production of each state are given in Table III. By an inspection of this table, it is possible to estimate the production of the two principal kinds of ship lumber, namely, Douglas fir and southern yellow pine. The pine growing states turned out 17,010,000,000 feet and the fir states, 5,640,000,000 feet in 1915. In 1916, the production of the fir states was approximately 7,000,000,000 feet. About 10 per cent of the Pacific coast cut is available for ship work. In other words, as far as lumber supply is concerned, the Pacific coast mills alone can turn out sufficient material for 400 3000-ton ships in a year and the southern mills, because of the smaller size of pine timbers, enough for 500 to 600 more, provided satisfactory labor supply and mill conditions can be obtained.

Southern yellow pine is the most abundant of all ship materials, and on account of its wide geographical distribution, comparatively close to the great eastern centers of population, it is extensively employed in building wooden vessel of all kinds. It comes in sufficiently large sizes so that the principal elements of the ship’s structure can be worked up in a comparatively few pieces, without the necessity of resorting to an abnormal number of butts and scarfs. Yellow pine is an even grained, easily worked, dense wood Detailed figures on the strength of pine timbers are given in Tables I, II and IV.

Pine is an unusually durable wood, even when subjected to long continued stresses in a ship’s structure. In the tables just referred to, the modulus of rupture, or breaking strength, of southern pine is given as varying from 6437 to 5948 pounds per square inch for the green material and 7033 to 5957 pounds for air-seasoned timber. The weight per cubic foot varies from 38.6 to 31.4 pounds. Ships constructed of southern pine along the Atlantic and gulf coasts have a special strength advantage, in that, when possible, natural crooks have been used for the curved frame members in nearly all cases. Such timbers are appreciably stronger than the sawed frame construction. As a material which is suitable for ship construction, Douglas fir, grown on the Pacific coast, is fully as important as yellow pine, and on account of the exceptionally large size of the trees, and the relative light-

ness of the wood, this timber has peculiar advantages of its own. Concerning this wood, the United States forest service, in Bulletin No. 88, has put itself on record as follows:

“Douglas fir may perhaps be considered the most important of American woods. Though in point of production it ranks second to southern yellow pine, its rapid growth in the Pacific coast forests, its comparatively wide distribution and the great variety of uses to which its wood may be put, place it first. As a structural timber it is not surpassed and probably it is most widely used and known in this capacity.”

Fir an Important Wood

Douglas fir comprises more than 25 per cent of the standing timber supply of the United States, including both hard and soft woods. The timber stand of Washington and Oregon is such as to insure a permanent source of supply of the highest class of lumber for shipbuilding. Also, the winter climate in this vast, western timber-belt is mild, enabling the lumber camps and mills to operate continuously, thereby producing a steady supply of manufactured products.

Practically all log transportation is by water and many of the mills are located on tidewater, in close proximity to shipbuilding plants. These conditions make it possible to produce lumber for ship construction at a minimum operating cost.

Pacific coast logging operators are provided with equipment specially adapted for handling large logs. Under the ordinary methods of procedure, the logs are hauled out from the places where the trees are felled by steel cables operated hy powerful hoisting engines. This operation is termed yarding. The yarded logs are usually rolled onto flat cars or specially constructed trucks, on which they are hauled to the water, either a river or tidewater. Here they are made up into rafts and towed to the mills. To some mills, of course, the logs are delivered direct by rail.

Big Timbers are Cut

The mills on the Pacific coast are equipped with extra heavy facilities for handling big logs and getting out big timbers and heavy planks specially suited to ship construction. Both large circular and band saws are used to work up the logs, while heavy planing mills are provided to dress the timbers. The modern mills are also completely provided with power-driven roller tables and transfers for handling the lumber during the process of manufacture. The accompanying illustrations show the essentials of the logging and lumbering operations on the Pacific coast.

Douglas fir trees grow commonly from 3 to 5 feet in diameter and from 175 to 250 feet high. Tremendous timbers, particularly suited to shipbuilding, therefore are available in quantity. Structural timbers of Douglas fir, 18 x 18 inches in section and 120 to 140 feet long, may be obtained from mills at any time, and timbers 36 inches square and 80 or 90 feet long are equally available. By the use of such timbers, the largest boats can be constructed with a minimum of splicing and scarfing, which not only reduces labor costs but materially increases the strength or seaworthiness of the vessel.

Douglas fir has an average specific gravity of 0.53 based on its oven dry volume. The specific gravity based on green volume, before shrinkage, is 0.46; based on air-dry volume it is 0.48. The green wood weighs 38 pounds per cubic foot, or 3.166 pounds per board foot and the air-dry wood 34 pounds per cubic foot or 2.836 pounds per board foot. These weights vary in fir as in other woods but the foregoing figures are reliable averages. A knowledge of these figures is indispensable to the naval architect or shipbuilder, in computing the weights, trim and displacement of his vessel. The method of figuring these weights will be brought out later in this book. Too many wooden ships at the present time are constructed and trimmed by guesswork, resulting in some exceedingly costly experiences for the shipowner.

Preservatives are Recommended

Douglas fir and southern pine are on a par as to durability, although like other woods when used for shipbuilding, precautions should be taken at the time the boat is constructed' to see that preservatives are effectively applied and that the necessary amount of ventilation is supplied to prevent the collection of moist, stagnant air in any part of the vessel. For preserving the timber, common salt is frequently introduced between the frame joints and between the frame members and the planking and ceiling. Most modern shipbuilders, however, prefer creosote, carbolineum, or some similar compound applied with a brush or old broom to the joints during the process of construction.

On account of differences of opinion recently voiced regarding the advisability of building wooden boats of green timber to meet the present submarine emergency, the following data on the shrinkage of Douglas fir, from a pamphlet by Howard B. Oakleaf, United States forest service, Portland, Ore., are presented:

“Douglas fir does not shrink much, and for this reason it is possible to

use partially dried material in emergencies, without fear that the additional drying after the material has been shaped will open the seams or cause undesirable stresses in the members. The following figures are given for the information of those desiring to know the amount that Douglas fir will shrink under normal conditions from green to air dry: Radially, 1.52 per cent, tangentially, 2.37 per cent, and longitudinally, 0.0091 per cent.” Tables I and II will be found to contain complete data on the strength of the principal American woods used for shipbuilding and other structural purposes. While it is difficult to obtain correct comparisons of the strength properties of structural timbers, yet, from a practical point of view, the full structural sizes furnish the data sought by naval architects and shipbuilders to guide them in their designs.