Chapter XXVII: Rafts and Catamarans, and How to Make Them

BY W. J. GORDON AND W. L. ALDEN.

Over twenty years ago the Fairlie foundered in the Indian Ocean. Spars had been thrown overboard to form a raft, yet before anything but the skeleton of the framework could be lashed together the ship went down. The crew jumped into the square, scrambled on to the boundary spars, and remained astride them with their legs in the sea until they were rescued a day or two afterwards.

This is as simple a raft as any recorded in shipwreck annals. But what is a raft? It is indeed a difficult thing to define. Rafts are of all shapes and sizes, varying from the few booms of the Fairlie up to the elaborate raft of the Medusa, of which the model was shown in the London Fisheries Exhibition. A raft would seem to be any floating substance on which a man can sit or stand. Boys have paddled in a pond on rafts of a couple of planks, soldiers have crossed rivers on rafts of barn-doors, and we hear of armies using rafts of house-roofs, and wooden-shed walls, and casks and inflated skins, and pontoons of all shapes, of tin, zinc, copper, iron, leather, wood, and canvas.

Perhaps the simplest kind of river raft is that common in South Africa, where a stack of reeds some fifty feet in diameter is pushed into the water and allowed to float down stream, each day, as the under stems get waterlogged, more being cut from the banks and thrown on to the heap. A similar rough raft is not uncommon amongst us in winter, when the ice is very thin, for if a heap of reeds is then thrown on to a slab of ice, and well watered, a solid mass can be built up with alternate layers of reeds and ice which will float considerable weights. Besides the floating stack there is another reed raft in use amongst the Kaffirs, made of a mattress of reeds about four feet long, three feet broad, and eight inches thick, tied together with strips of the reeds themselves, with reed posts and railing round.

Skins stretched and inflated are in use all over the globe for raft purposes. In Peru a hide pinched up at the corners, secured there with a thorn, and dried in the sun, furnishes the only boat. In another American form we have holes bored all round the edge, a thong run through them and pulled tight over a framework of withies,--in fact, a coracle such as the Celts were so fond of, the washing basket with the waterproof covering which exists on the coast of Ireland to this day.

The contracting force exercised by skins as they dry has a great deal to do with the water-tight qualities of hide boats, as, in all cases, the framework is covered as soon as possible after the death of the animal.

It is astonishing what simple things have been made into boats. Admiral Fitzroy once sent a party of sailors ashore, and while they were encamped their boat was stolen. Out of the boughs of the trees around them they made a large basket, covered it with their canvas tent, puddled the inside with a little clay, and put to sea, spending eighteen hours in this crazy contrivance before they got back to safety.

Alexander’s army passed the Indus, as Hannibal’s did the Rhine, on rafts made of inflated skins, or of skins stuffed with hay. On the Tigris and elsewhere at this very day such goat-skin rafts are still in use. The skins are lashed to a framework with one of the legs of each animal upwards; through this leg the air is driven in, and, as the traveller journeys down the stream, he visits the skins in succession and blows in fresh air to make up for what has escaped. A single ox-hide when inflated is said to make a float capable of sustaining three hundred pounds.

Casks are almost invaluable in raft-making, and many a shipwrecked crew has been saved on a platform lashed to floating barrels. One of the early lifeboats simply consisted of a boat with holes bored in her bottom and empty casks lashed inside her, the casks giving the floating power while the shape of the boat was retained. Four spars lashed together with a cask at each corner and a square of canvas fixed on them was all that one of the patent life-rafts consisted of.

Casks furnish great floating power in such a convenient form that it is hardly to be wondered at that they have been used over and over again in the construction of military bridges where boats have been unattainable. They are, however, but a makeshift, pontoons nowadays being always carried. When Darius crossed the Bosphorus and afterwards the Danube he did it on a bridge of boats oft very elaborate construction. When Xerxes crossed the Hellespont he had two bridges, one consisting of three hundred and sixty vessels anchored side by side and head to stern, and another, nearer the Archipelago, of three hundred and fourteen vessels similarly anchored. These were connected by cables, a platform of planks was laid stretching from each to each, and on the platform from shore to shore there was laid a thick bed of earth to form the road on which the Persian hosts passed into Europe. At Xenophon’s passage of the Tigris thirty-seven vessels were used.

The most famous boat-bridge in modern times was that thrown by the British over the Adour when Wellington invaded France. The bridge was 810 feet long, and was at first supported on hawsers, which were kept tight by capstans placed in the centre of each of the thirty to forty-ton chassemarées which formed the piers. These chassemarées were moored side by side at a distance of forty feet from each other’s centres, so that the intervals were equal. The platform was after a day or two shifted on to balks. To protect the bridge a boom was thrown across the river on each side of it. The best of the raft-bridges was Sokolniki’s over the Niemen at Grodno in 1792. The trunks, fifty to sixty feet long and about two feet in diameter, were lashed together in tens and joined end to end until they reached across the stream. The bridge was three hundred and sixty yards in length, and formed a great curve towards the current, with the centre of the curve supported by an anchored vessel. These trunks were lashed together. A better plan, however, is that adopted by the Canadian timber-men, who cross-lay their rafts, bore an auger-hole at the corners through both thicknesses, and fix a wedge in the cleft end of the stick which keeps them together. As the stick is driven home the wedge is forced upwards into the end and makes all fast.

On the coast of India it is a very common thing to see two or three natives afloat on a raft made of three logs of wood--of the pine varnish-tree--the centre log being about five-and-twenty feet long and the breadth of the three together about a yard. These rafts are manœuvred with very great dexterity, and safely brave the roughest seas. Similar to them is the Brazilian catamaran, which carries a large triangular sail.

The Cingalese catamaran is a log of wood rounded beneath, and scooped out, with two planks lashed on the top, so as to increase the height above water. It has a boat-shaped outrigger, supported on two curved poles, to enable it to carry the large lug-sail, which in a fresh breeze so heels it over that the crew have to sit well out to windward on the connecting-bars to balance the swift but crazy craft. In the Mauritius the catamaran is an ordinary boat with a smaller boat at the end of the outrigger, in which is set a peculiar mizzen. In the Fijis the catamaran becomes a double canoe, with both hulls exactly the same, and bearing a platform giving just a little play, so as to allow of the individual peculiarities of the boats being sufficiently humoured.

These boats, although they may in a few rare cases upset end on--that is, turn a somersault--are the safest craft in the world, for, consisting as they do of double hulls sustaining a raft, should anything go wrong with the hulls, the raft will never sink, but will simply settle down until it floats on the waves. Owing to the great breadth there can be no question of ‘initial stability,’ and an ordinary capsize is impossible, while the very light draught of the hulls will take the craft over places where even a rowing-boat would meet her doom.

To build such a craft is not difficult, and Mr. W. L. Alden has recently shown us how it can be well and cheaply done. Adopting the principle of the flying proa of the Ladrones, which are credited with their twenty knots on a beam wind, he makes his hulls quite flat on one side, and thus avoids the ‘funnel difficulty,’ as it was called in the case of the Castilia and other steam catamarans, where the inner sides of the hulls being curved, the water between them was heaped up as it rushed through the narrowing strait. To make such a catamaran as that shown in our sketch--a craft speedy, safe, and handy, which is easily built, and will bear any amount of rough usage--four deal planks are required. These should be fifteen feet long, eighteen inches wide, and an inch thick. The width is unusually great, but should single boards not be obtainable, two or three boards can be keyed together so as to make it up. Take one of the planks, which should have been bought ready planed, divide it into five equal parts as shown in the diagram, and at each of the four divisions screw, with brass screws, a three-inch batten three-quarters of an inch thick. This will not only prevent the plank from warping, but will strengthen the joints if you are working with a board that has been made up.

Now shape the ends as shown in Fig. 1, first with a saw and then with a draw-knife and spokeshave. Take another of your eighteen-inch planks and treat it in exactly the same manner, and when you have finished the curves, which should exactly resemble the others, cut off along the longer side an inch and three-quarters off every cross-piece, so that when the planks are placed at right angles together they will fit close. Whitelead these edges thoroughly, and then nail the planks together with galvanised iron nails, as shown in Fig. 2, which gives you a section end-on. Now cut four quadrants eighteen and a quarter inches radius, and off one side cut a strip an inch wide and trim the other end so as to leave you a piece of the shape shown in Fig. 3, one side of which (A B) is seventeen inches long, and the other (A C), eighteen inches, and which is so made to fit exactly into the angle made by the broad plank and close against the battens as sketched in Fig. 4. Finish all the edges off smooth and square and true, whitelead them well, and fix them in with galvanised iron nails.

Now make, or get made, six iron staples such as are shown in Fig. 5, where the distance from A to B horizontally and A to C vertically is just four inches. The iron is best an inch and a half wide, between an eighth and a quarter of an inch thick, and in it should be three holes, shown at P and in the ears marked H, large enough for quarter-inch bolts. You also require six other staples of the shape shown in Fig. 6, made of half-inch rod iron with counter-sunk sockets for the screws, and these, like the eared sockets, must be four inches wide.

Screw down one of these eared sockets just where the curve goes off on the narrower side, as shown in Fig. 7, and in the centre fix a third. Use galvanised nuts and bolts for fastening, with a thin leather washer under the bolt and an oak washer under the nut, and make the holes watertight by hard screwing and plenty of whitelead. To the other edge at the angle, and so as to project beyond it and correspond with the eared sockets, fix your flat staples, as shown in Fig. 8, so that a bar can be passed through each, as shown in Fig. 9. Along the centre of the board above which the staples project bore five holes an inch in diameter, one in the centre of each of the five divisions with which you started, and then having first fitted a thin batten from A to B, as shown in Fig. 4, and let it down flush into the quadrants, give the construction a thorough coating of red-lead paint inside and out.

Next get some canvas forty inches wide. Coat it well with boiled oil, dry it thoroughly, and placing the lower edge of your framework along its centre, strain it up tight all round. Use copper nails to fasten it with, and running a streak of paint along its lower edge, finish it there with a thin oak batten, steamed to shape if necessary, and screwed on outside while the paint is wet, so as to serve for protection and form the keel. Now give your pontoon a good even coat of paint, and when that is thoroughly dry give it a trial coat of any colour you please.

Now make another pontoon in exactly the same way, and when it is finished fasten both hulls together with three pieces of scantling, as shown in Fig. 9. The cross-bars should be nine feet long and four inches square, and kept in their places by copper bolts slipped into them through the holes in the centre of each of the sockets.

Next make a platform of quarter-inch boards by nailing them together in two layers at right angles to each other. Use copper nails and clinch them. Round the outside of the platform run a low ridge of hard wood, so as to turn it into a tray, as shown in the sketch, and keep the water off the edges of the boards. Cut out a dozen grooves for the tops of the sockets to sink into; put the platform flat down on the cross-bars, and screw it into its place with galvanised nuts and bolts passing through the bars. The catamaran is now finished and ready for the mast, which can be stepped in an iron collar raised on three strong iron supports about twenty inches long, strongly riveted and bolted into the deck. Her sails and spars are made in the ordinary manner, the same as those of other boats as previously described. She requires a traverse or ring for the painter, and a rowlock to steer her by, and then, having carefully overhauled her to see that she is thoroughly watertight, whiteleaded every crack and crevice, and remembered throughout her construction never to have nailed a nail or screwed a screw without first covering it with whitelead, you can give her a farewell top coat of colour. Wait till she is thoroughly dry, and then, having placed a cork securely in each of the ten holes leading to her watertight compartments, which holes were made for you to get the water out in case any should leak in, you can launch her, seize your steering rudder, and be off. She will go anywhere and do anything, providing always that the waves are not rough enough to wash you off her deck.

Says Mr. Alden: ‘There is no better boat to cruise in than such a catamaran. At night you anchor her, unship your mast, pitch your tent, and sleep safely and comfortably. If you come to a dam you can take the craft apart and carry her round piecemeal. If you once try to build a catamaran and succeed--as you certainly will if you have patience--you will have the safest and most comfortable sail-boat in the world.’