THE LIFE-BOAT FLEET Motor Life-boats, 124 :: Pulling & Sailing Life-boats, 45 LIVES RESCUED from the foundation of the Institution in 1824 to November 30th, 1935 - ... 64,350 The Woods of which a Life-boat is made.

By S. T. C. Bane, M.I.N.A., the Institution's Surveyor of Life-boats.

OUR life-boats are built of wood. We use wood because we have found that, given an equal weight, it stands punishment better than steel. We have had steel life-boats. All the steam life-boats were of steel. They did good service, but our experience with them satisfied us that wood was better in a boat which must be prepared to stand a lot of knocking about, which may be flung against wrecks and rocks or bumped violently on sand- banks, and which must be able to go on with her work after it as if nothing had happened.

If you take a single steel plate you will find that it can stand a good deal of rough usage, but in life-boats the plates must necessarily be light, and if the boat should be knocked about the rivets are apt to draw. The rivets are the weak point in a steel life-boat.

A time may come when, after further experience of welding, we shall have done with riveting. The life-boat service may then take to steel.

At present wood holds the field and steel is used only for the bulkheads of our larger life-boats. It is, however, only fair to say that on the Dutch coast, where there are no rocks, the large life-boats are of steel.

The woods we use are English oak, Canadian rock elm, Honduras maho- gany, Burmese teak, Canadian white deal- and Columbian red cedar. By the time a life-boat is complete she has in her woods from nearly half the Empire.

Oak and Rock Elm.

Each wood is used for some parti- cular part of the boat, and has been chosen for it because it has some special quality which makes it more suitable for that part than any other wood. English oak is used for the stem and stem of the boat, because of two qualities. The first reason is that it is without rival for its strength and durability. , It weighs from 40 Ib.

to 53 Ib. per cubic foot and its average tensile strength—that is to say its resistance to pulling—is nearly 3| tons per square inch. The second quality is that it can be got grown in the shape needed. A curved piece of wood is, of course, very much stronger if the curve is a natural growth than if it has been made by steaming and bending a straight piece of wood.

Canadian rock elm is used for the framework of the boat, and in the case of light boats for the keel also. It is tough, straight-grained and very resilient, Tike a bundle of canes.Unlike oak, it steams and bends well.

It is heavy, almost as heavy as oak, 43 Ib. to 46 Ib. to the cubic foot, and it has a greater tensile strength even than oak—4 tons to the square inch.

Mahogany and Teak.

Honduras mahogany is used for the deck of the boat and for the planking or skin. This skin is put on over the frame in two thicknesses, with calico and white lead between them. It has been chosen for these particular parts of the boat because it is tough, very difficult to split, and at the same time easy to steam and bend. It is, in fact, a strong, very good-natured, adaptable wood. Its weight is from 37 Ib. to 40 Ib. the cubic foot, and its strength is about 1J tons to the square inch.

Burmese teak is not as light a wood as mahogany, and it is much more brittle, but it has the advantage of resisting decay better—it is almost everlasting. For that reason it is used instead of mahogany for the planking and the decks in life-boats, in which its greater weight does not matter, and in which (for example in life- boats which lie afloat) its resistance to decay is a valuable quality. For the same reason it is used also, instead of the lighter Canadian rock elm, for the keels of the larger life-boats.

Its weight is 45 Ib. to 50 Ib. to the cubic foot, and its strength 1| tons to the square inch. Teak has another valuable quality which no other wood has. Its oil preserves from rusting iron driven into it.

Deal and Cedar.

The two light woods, Canadian white deal and Columbian red cedar, are used only for the air-cases, of which there are from 70 to 160 in a life-boat.

The white deal is tougher and more elastic than the red cedar, but it is heavier. The one weighs 21 Ib. to 40 Ib.

to the cubic foot and the other 20 Ib. to 26 Ib.

White deal is used for the air-cases, except in those life-boats in which it is necessary to save weight as much as possible. In these boats red cedar is used instead. At one time (nearly fifty years ago) air-cases of copper were tried. They were a failure. In boat after boat which had been fitted with them it was found that they had corroded and given way under the frequent contraction and expansion caused by changes of temperature, and water had got into them. The copper cases were replaced by wood.

Such are the six principal woods which make a British life-boat and the qualities for which they are chosen, but to complete the tale it should be added that Norway fir is used for the masts ; a little greenheart (a very hard, smooth African wood) is used wherever there is likely to be a great deal of friction; and a little sabicu, another hard African wood, is used for the cleats on which ropes are made fast. Sabicu has a very smooth surface and is chosen for that quality, so that the ropes will run easily over the cleats when they are unfastened.

Seasoning.

Wood is fascinating to use, but very difficult. It has to be chosen with great care. It has to be felled at the right moment; that is to say, in the autumn, when the flow of sap is least active.

It has to be stored with plenty of air- space, in order to season it gradually ; for if not well seasoned, there is a certainty that, when built into the boat, the excess of moisture in it will be a breeding ground for the microbes of dry rot. At the same time, some moisture must be left in all wood; if not, the absorption of exterior moisture would cause the wood to swell. About a quarter of the weight of fresh wood is moisture, but wood sometimes arrives from overseas of which as much as 35 per cent is moisture. The aim of the seasoning is to reduce the moisture to that point at which there will be least contraction and expansion of the wood under the influence of changes of weather. The amount which should be left depends on the purpose for which the wood is to be used. In life- boats it is necessary to reduce the moisture to, at most, 20 per cent.

In wood to be used in steam-heated houses the seasoning must be carried much farther and, at most, 9 per cent of moisture left in it.

This process of drying out the mois- ture, or seasoning, must be done gradually and naturally. If it is done by violent artificial means, it makes the wood brittle. The time it takes varies enormously according to the wood (hard woods take longer than soft), the bulk of the wood and the time of year, but a three-inch oak plank, if kept under cover in a dry atmosphere, can be seasoned in three weeks. It can be —but the longer it is left to season the better.

Few modern shipyards can afford to have capital lying idle, and it is very hard to find a good stock of seasoned timber of the sizes the life-boat service needs. Special and very careful arrangements have to be made. In the days of wooden warships the Government employed skilled ship- wrights to find and choose its timber, and these men travelled far. So the Institution to-day employs two timber- converters—as they are now called— to inspect and purchase timber for it.

Choosing Oaks.

Let us suppose that the Institution wishes to increase its supply of oak, of which it usually keeps in stock 80 to 100 crooks. It sends out blue-prints, showing the sizes and curves needed, to timber merchants, usually in the Midlands, Eastern Counties, Hampshire and the Isle of Wight. The merchants let the Institution know of any likely trees that they have and the timber- converter goes down to see them.

Oak with the crooks needed is very hard to find and disappointments are many. On one occasion the timber- converter was taken by the merchant to see some trees still standing. On the way they passed a tree which promised to yield a splendid stem.

They hurried across the field, and the timber-converter walked round the tree—and disappeared. He had stepped right inside it! Oak is usually bought just after felling, and the transport alone, as the first photograph on page 547 shows, is a considerable labour.

Oak " crooks " (as we call any curved part of an oak tree) which are of the right shape are increasingly difficult to get. If any owners of country property should read this, I hope they will remember that they could make no gift to the life-boat service more welcome than oak timber. What is wanted is large oak, between 150 and 200 years old, and anything from 9 feet to 14 feet in girth. The shapes needed can best be seen in the second photo- graph on page 547.

For the other woods, all of which come from overseas, the converters visit the importers of timber at the London docks, and occasionally at other ports. The woods will be found there usually in logs of about 16 inches square and 24 feet to 34 feet long. All woods are kept in airy sheds, except the Canadian rock elm, which is kept sunk in the mud at the bottom of the docks, because in the open air it very quickly splits (or, as we say, "shakes," a " shake" being a split which goes from the surface to the heart, the whole length of the log). Even after it is bought it is kept in salt water for another six months or more, and when it is wanted for building is cut up and kept in a shed for a very short period of seasoning before it is used. Pine also is kept sometimes in rafts afloat, for the same reason.

There is no space to follow the history of all these timbers through their transformations and journeys before they reach the Port of London, but let us see what has happened to the logs of teak before the timber converter buys them on the Thames.

The Teak Forests of Burma.

They come from the vast forests on the hills of Upper Burma, for it is only in the moist, hilly country that teak will grow. These forests are under the control of the Forest Depart- ment of the Government of Burma, which leases them to private firms, most of which are European.

Before any trees can be cut down they must be chosen and marked by the Forest Department's officer. Then they are " girdled " ; that is to say, a wide circle is cut round the base of the tree. This stops the flow of sap, and gradually kills the tree. The tree must not be cut down until it is dead, and it takes three years to die. Then it is felled, and felling is no easy business in forests which grow at anything from 1,500 to 4,000 feet above the sea on steep and rocky hills. After the felling the trees are cut into logs. Then begins the work of " extraction," as it is called, a word which has painful memories for most of us, but which is very well chosen, considering the difficulties of getting the logs down to the sea. They travel by water, but to reach the " floating point " on the nearest stream they are dragged by buffaloes, if the country is easy, and by elephants where it is steep and rocky. Some of the firms have as many as 2,000 elephants.

If possible, the bed of a stream is used as the road. It is a road where rocks may have to be blasted away and paths cut round waterfalls. In this laborious way the logs reach floating point.

From there they go down the small streams for perhaps a hundred miles, before they reach one of the main tributaries of the Irrawaddy, the great river of Burma ; then another hundred miles before they reach the Irrawaddy itself; then another three hundred miles down the Irrawaddy to the great sawmills at Rangoon. That journey by buffalo or elephant, by stream and river, takes on an average five years.1 Now let us return to the wood when it is in the hands of the Institution and ready to be made into a life-boat.

Converting into Flitches.

The first business is to convert this timber into flitches; that is, the smallest sections of wood out of which the particular part of the boat required can be cut. The photograph on page 549 shows an oak crook in the rough.

The first step of converting it into flitches has just begun. It will be divided and divided again before the work of shaping it begins. In the first photograph on page 551 the crook is taking shape as two " knees," to form part of the after end of the boat.

Oak is the most difficult of all the timbers to convert. No machinery is used. Two men with a dozen or so different types of long saws, some 1 This brief description of cutting and transporting teak has been taken from a ful! account of the working of the Burmese teak forests kindly sent to the Institution by Mr. David Brown, of the Bombay Burma Trading Corporation. The three photographs of the forests were also taken by Mr. Brown.

wedges, chalk, and string, and a long pit—these are better than the finest machinery, and will get twice as much timber out of any crook. One man works above the crook, and one in the pit below it. Their sawing is very clever. It is by no means the mechan- ical, quiet, steady effort the photograph on page 549 suggests. These men are not afraid of curves. They often have to make them, for oak has a habit of growing unconcernedly round the strangest things. The saw will often come up against, and have to cut round, flints, iron staples, wire and nails.

Stranger still, it will not infrequently cut into a hole in the middle of the tree containing a nest and dried-up eggs. Such things are found buried in the oak, very often just at that place where they will spoil the con- verter's hope of a faultless piece. The other woods only require straight cutting, and for that reason can best be cut by machinery.

Wastage.

There must inevitably be a great deal of wastage in converting the timber. On an average 3| tons must be purchased for every ton used.

That is to say, 71 '5 per cent of the wood is wasted, but that 71*5 per cent is large- ly made up of sawdust and shavings, owing to the tremendous amount of shaping that is necessary. The wastage of oak is certainly very much less than it was in the dockyards in Nelson's day, in spite of the fact that in a modern life-boat there are far fewer shapes for which the small odds and ends of oak can be used than there were in the wooden battleships a hundred years ago. The smaller wastage is the result of skilful selection and converting.

Let us see how much timber goes into a modern motor life-boat of the 46-feet Watson cabin type. That type when complete weighs, without her crew on board, just over 18 tons. She will have in her approximately 12 cwt. of oak, 1 ton 8 cwt. of rock elm, 5 tons of mahogany, 6 cwt. of teak, and 14 cwt. of white deal. That is 8 tons of timber altogether. That timber, in the rough, as it was bought by the Institution, will have weighed over 19J tons..