[Ill.u.s.tration: Figure 10.--A RECONSTRUCTION OF INBOARD WORKS of the _Steam Battery_, for construction of the model in the Museum of History and Technology.]

For 18 years Petty did no more with the type, but finally, in July 1684, he laid down a still larger sloop with two decks and a mast standing 55 feet above her upper deck. She was named _St. Michael the Archangel_ and is probably the design in Pepys' _Book of Miscellaneous Ill.u.s.trations_ in Magdalene College, Cambridge, England. This vessel proved unmanageable and was a complete failure.

[Ill.u.s.tration: Figure 11.--MODEL LINES REDRAWN to outside of plank to show hydrodynamic form of the _Steam Battery_.]

Though the double canoes of the Pacific Islands were probably known to some in Europe in 1662, there is no evidence that Petty based his designs on such craft. He appears to have produced his designs spontaneously from independent observations and resulting theories.

Before Petty concluded his experiments, a number of double-hull craft had been produced by others; however, some "double" craft, such as "double shallops" may have been "double-enders," as shown by a "double-moses boat" of the 18th century and later.[16]

The use of two canoes, joined by a platform or by poles was common in colonial times; in Maryland and Virginia, dugouts so joined were used to transport tobacco down the tidal creeks to vessels' loading. Such craft were also used as ferries. M. V. Brewington's _Chesapeake Bay Log Canoes_[17] and Paul Wilstack's _Potomac Landings_[18] ill.u.s.trate canoes used in this manner. A catamaran galley, two round-bottom hulls, flat on the inboard side (a hull split along the centerline and the inboard faces planked up), 113 feet long and each hull a 7-foot moulded beam, 6-foot 6 inches moulded depth, and placed 13 feet apart, was proposed by Sir Sidney Smith, R.N., in the 1790's, and built by the British Admiralty. Named _Taurus_, she is shown by the Admiralty draught to have been a double-ender, with cabins amidships on the platform, an iron rudder at each end (between the hulls) steered with tillers (to unship), and with a ramp at one end. The plans are undated, signed by Captain Sir Sidney Smith, and a field-carriage gun is shown at the ramp end of the boat. This, and the heavy rocker in the keels, suggests the _Taurus_ was intended for a landing boat. No sailing rig is indicated, but tholes for 12 oars or sweeps on each side are shown. The oarsmen apparently sat on deck, or on low seats, with stretchers in hatches between each pair of tholes (Admiralty Collection of Draughts, The National Maritime Museum, Greenwich, England).

[Ill.u.s.tration: Figure 12.--GENERAL PLAN of the _Taurus_, a catamaran galley gunboat proposed by Sir Sidney Smith, R.N., to the British Admiralty in the early years of the French Revolution. From the Admiralty Collection of Draughts, National Maritime Museum, Greenwich.]

Another experimenter with the double-hull type of vessel was a wealthy Scot named Patrick Miller who was particularly interested in manual propulsion of vessels, employing geared capstans to operate paddle wheels. In a letter dated June 9, 1790, Miller offered Gustav III of Sweden a design for a double-hulled 144-gun ship-of-the-line (rating as a 130-gun ship) propelled by manually operated capstans connected to a paddle wheel between the hulls. She was rigged to sail, with five masts and was to be 246 feet long, 63 feet beam, and 17 feet draft; the hulls were 16 feet apart.

This project was submitted by the King to Fredrik Henrik af Chapman, the great Swedish naval architect, who made an adverse report. Chapman pointed out in great detail that the weight of the armament, the necessary hull structure, the stores, crew, ammunition, spars, sails, rigging and gear, would greatly exceed Miller's designed displacement.

He also pointed out the prime fault of catamarans under sail--slow turning in stays. He suggested that the speed under sail would be disappointing. He doubted that a double-hull ship of such size could be built strong enough to stand a heavy sea. He remarked that English records showed that a small vessel of the catamaran type had been built between 1680 and 1700 which had sailed well (this may have been one of Petty's boats), and that "36 years ago" he had seen 8 miles from London, a similar boat that had been newly built by Lord Baltimore and was about 50 feet long; this was a failure and was discarded after one trial.

Therefore, said Chapman, the Miller project was not new but rather an old idea. Chapman's final remark is perhaps the best ill.u.s.tration of his opinion of the catamaran, "Despite all this, two-hull vessels are completely sound when the theory can be properly applied; that is in vessels of very light weight, and of small size, with crews of one or two men."

A "model" of such a double-hull ship--the _Experiment_, built at Leith, Scotland, in 1786 by J. Laurie--was sent to Sweden by Miller. She was 105 feet long, 31 feet beam, and cost 3000. This vessel arrived in the summer of 1790 and King Gustav in a letter dated July 26 ordered Col.

Michael Anckersward to welcome the vessel at Stockholm. The King presented Miller with a gold snuffbox and a painting was made of the vessel. The _Experiment_ had five paddle wheels in tandem between her hulls, operated by geared capstans on deck. These gave her a speed of 5 knots but caused the crew to suffer from exhaustion in a short time. The vessel was badly strained in a storm and was finally abandoned at St.

Petersburg, Russia.[19]

[Ill.u.s.tration: Figure 12.]

Miller later turned to the idea of employing steam instead of manual power and built a 25-foot double-hulled pleasure boat of iron fitted with a steam engine built by William Symington. Also named _Experiment_, she was an apparent success, so Miller had a 60-foot boat built of the double-hull design and fitted with an engine built by Symington. She reached a speed of 7 mph on the Forth and Clyde Ca.n.a.l. However, Miller lost interest when he found that the Symington engine was unreliable and that Great Britain showed very little public support for such projects.

Fulton was acquainted with Symington's work and probably had heard of Miller's vessels. At any rate, he employed the double-hull principle in his steam ferryboats, the first of which was the _Jersey_, a 188-ton vessel built by Charles Browne, which began service July 2, 1812. The next year he had a sister ship built, the _York_. These vessels were based on his patent drawing of 1809. In 1814 he had another vessel of this type built, the _Na.s.sau_. It was, therefore, logical that he should apply this design to the _Steam Battery_. The double-hull design had worked well in these ferries, and the design would give protection from shot to the paddle wheel. The _Battery_ would have the ability to run forward or astern so as not to be exposed to a raking fire from the enemy while maneuvering in action. The application of this "ferryboat"

principle to the _Battery_ reduced the need for extreme maneuverability, the catamaran's weakest point, even at low speed.

The resistance factors in the design are of relatively small importance, for the speed possible under steam in this period was very low. However, the plans show an apparently efficient hull form for the power available, aside from the drag of the beams across the race in the vicinity of the keel. The displacement was adequate. The height of the gun-deck above the water at the race made the _Battery_ unsuitable for rough-water operation, but there is no evidence that Fulton or the sponsors of the vessel considered the _Battery_ as a coastwise or seagoing steamer. However, the clearance of the gun deck above the water and the dip of the paddle wheel would have made the additional weight of an upper- or spar-deck battery prohibitive even had experience in action proven it desirable.

Sail and Inboard Plans

[Ill.u.s.tration: Figure 13.--LINES OF _Taurus_. From the Admiralty Collection of Draughts, National Maritime Museum, Greenwich.]

The sail and rigging plan is likewise a Danish copy and shows the two-masted lateen rig employed. The hull is shown with bulwarks and gunports on the spar deck but no other evidence that the _Battery_ was finished in this manner has been found. The rig resembles that of some of Josiah Fox's designs for Jeffersonian gunboats--double-enders designed to sail in either direction but without the jibs. The topmasts do not appear to be more than signal poles and apparently were not fitted with sails; however, some European lateeners did have triangular topsails over a lateen and it is possible the _Battery_ may have carried such sails. Considering the stability and displacement of the _Battery_, the rig is very small and not sufficiently effective. Shrouds were not required; the masts were supported by runners that were shifted when the yards were reversed, and in tacking. Apparently the jibstays also could be slacked off so that the lateen yards would not have to be dipped under them.

[Ill.u.s.tration: Figure 14.--RUDDER DETAIL of _Taurus_. From the Admiralty Collection of Draughts, National Maritime Museum, Greenwich.]

The inboard profile is on tracing paper and the notes are in French.

This drawing is of a simplified hull form having flat-bottom hulls with chines. It is possible that this is a tracing of a preliminary drawing obtained by Marestier or Montgery, but no doc.u.mentation can be found.

Its importance is that it shows in some detail the engine and boilers, as well as the wheelbox, and another drawing of the paddle wheel, more or less duplicating the wheel shown in the Danish plan. No details of the deck arrangements are shown in any of the plans, except for the dome skylight over the fireroom in the boiler hull.

Both the lines plan and the inboard drawing show construction midsections and hull connections. These plans show that the engine was not inclined, but rather was vertical, contrary to Fulton's patent drawing. The piston rod and the crosshead obviously pa.s.sed through its gun deck in a large hatch. Also it is plain that there must have been large hatches afore and abaft the wheelbox to make the stepped wheelbox construction desirable. There also must have been a hatch in the gun deck under the domed skylight. It is improbable that the engine and skylight hatches were used for ladderways, pa.s.sing scuttles, or companionways.

The boilers are shown in the inboard profile about as described and drawn by Marestier but with two stacks on each boiler, one to each flue; Marestier's sketch in his report on American steamships shows the flues of each boiler trunked into a single stack. The battery had two boilers and the stacks are at the boilers' fire-door end. The steam lines came off the crown of the boilers and probably pa.s.sed through the ends of the wheelbox to the engine; a trunk for the steam lines would undoubtedly have been necessary.

[Ill.u.s.tration: Figure 15.--SKETCH OF 130-GUN SHIP proposed by Patrick Miller to King Gustav III of Sweden in 1790. In Statens Sjohistoriska Museum, Stockholm.]

[Ill.u.s.tration: Figure 16.--PATRICK MILLER'S manually propelled (paddle-wheel) catamaran ship _Experiment_, built at Leith, Scotland, 1786. Scale drawing in Statens Sjohistoriska Museum, Stockholm.]

The engine is shown to have had counterbalanced side levers, one on each side, and a single flywheel on the outboard side. The cylinder is over the condenser or "cistern," connected by the steam line and valve box on the side. The cylinder crosshead is shown in the inboard profile to have reached the underside of the beams of the upper deck. The crosshead was connected by two connecting rods to the side levers. These levers operated the paddle wheel by connecting rods to cranks on the paddle-wheel shaft. There is another pair of connecting rods from the side levers to the crosshead of the air pump. All connecting rods are on one arm of the side levers, the other end having only a counterbalance weight beyond the fulcrum bearing. The flywheel has a shaft fitted with two gears, and is driven through idler gears from gears on the paddle-wheel shaft; it turns at about twice the speed of the paddle wheel. No other pumps or fittings are shown in the engine hull, although manual pumps were probably fitted to fill and empty the boilers. Piping is not shown.

[Ill.u.s.tration: Figure 17.--PAINTING OF THE _Experiment_ in the Statens Sjohistoriska Museum, Stockholm.]

The four rudders, toggled in pairs, are shown in both the lines and inboard drawings, but the shape is different in the two plans. Operation must have been by a tiller under the gun-deck beams. The outer end of the tiller may have been pivoted on the toggle bar and the inboard end fitted, as previously described, with steering cable or chain tackles.

This seems to be the only practical interpretation of the evidence.

Reconstructing the Plans

In the model it was necessary to reconstruct the deck arrangements without enough contemporary description. The outboard appearance and hull form, rig, and arrangement of armament require no reconstruction, for all that is of importance is shown in the lines and rig drawings, or in the inboard profile. The masts are shown to have been stepped over the race on the gun deck. The iron stanchions are shown in the lines drawing and in the construction section. However, their position at the ends of the _Battery_ are apparently incorrectly shown in the original lines plan. The construction section shows these stanchions to have been stepped on the inside face of the inner ceiling and, as the ceiling structure was carried completely around the ship, the stanchions in the ends must have been placed inboard, as along the sides. The bowsprit was above deck and would probably be secured in the knighthead timbers at the ends of the hull, as well as by the heel bitts shown in the Danish lines drawing. With the riding bitts shown inboard of the heel bitts at each end of the vessel, it is obvious that she would work her ground tackle at both ends and would therefore require two capstans; the wheelbox would prevent effective use of a single one. The capstans might be doubleheaded, as in some large frigates and ships-of-the-line.

[Ill.u.s.tration: Figure 18.--SAIL PLAN OF FULTON'S _Steam Battery_ as reconstructed for model in the Museum of History and Technology.]

As to the remaining deck fixtures, hatches and fittings, these must be entirely a matter of speculation. Ladderways, pa.s.sing scuttles, hatches, trunks, galley, heads and cabins were obviously required in a fighting ship and can only be located on the theory that, when completed, the _Battery_ was a practical vessel.

It has been stated that the officers' cabins were over the race; the logical place for the heads, galley, wardroom and mess also would be over the race, giving the remaining part of the gun deck for the necessary hatches, ladderways, trunks, etc., in the two hulls, s.p.a.ce required for armament, and to sling the hammocks of a watch below. As the vessel was never fully manned, apparently, the s.p.a.ce for hammocks is not a serious problem in a reconstruction. If the vessel had been manned as proposed by 500 men, hammocks for over 200 would have been required, which would give very crowded quarters in view of the limited s.p.a.ce available.

Though no specific requirements were stated in the reports of the trials, it seems reasonable to suppose that additional hatches were cut in the decks to improve the fireroom ventilation. In the reconstruction drawings, these hatchways as well as the other deck openings and deck fittings--such as bilge pumps, companionways, skylights, binnacles, wheels and wheel-rope trunks, cable trunks, steampipe casings, and stack fiddleys--have been located in an effort to meet the imagined requirements of the working of a ship of this unusual form.

[Ill.u.s.tration: Figure 19.--MODEL OF _Steam Battery_ in the Museum of History and Technology. (Smithsonian photo 63990-E.)]

[Ill.u.s.tration: Figure 20.--LINES OF STEAMER _Congo_, built in 1815-1816 for the British Admiralty and converted to a sailing survey vessel. From Admiralty Collection of Draughts, National Maritime Museum, Greenwich.]

There are some unanswered questions that arose in the preparation of the reconstruction drawings. As has been shown, the original inboard arrangement plan found in Copenhagen shows four smokestacks, while Marestier's sketch of the vessel's boilers shows trunked flues indicating that two stacks were used. It is possible that the boilers were first fitted so that four stacks were required; alterations made as a result of steaming trials may well have included the introduction of trunked flues and the final use of two stacks in line fore-and-aft. This would have required a rearrangement of the fiddley hatches amidships.

Another troublesome question was the doubtful arrangement of the four companionways on the spar deck. Perhaps only two were fitted, one on each side of the officers' staterooms while the ladderways at the crew's end of the ship were simple ladder hatches.

The decision to use four bilge pumps is based upon the lack of drag in the keel of the hulls, which would prevent acc.u.mulation of bilge water at one end of the hull. The use of four single-barrel pumps instead of four double-barrel pumps may be questioned, for chain pumps requiring two barrels would have been practical.

Allowance for stores was made by use of platforms in the hold. It is known from statements made to the Court of Inquiry, that the magazines were amidships and that a part of these was close to the boilers. Fuel and water would be in the lower hold under the platforms; hatches and ladderways are arranged to permit fueling the ship.

A few prints or drawings of the ship, aside from the patent drawing, have been found. There are two prints that show the launch of the vessel. One, a print of 1815, is in possession of the Mariners' Museum, Newport News, Va., and is reproduced in Alexander Crosby Brown's _Twin Ships, Notes on the Chronological History of the Use of Multiple Hulled Vessels_.[20] A poor copy of this print appears on page 13 of Bennett's _Steam Navy of the United States_, and another and inaccurate sketch is shown on page 8. These pictures were of no use in the reconstruction as they show no details that are not in the Copenhagen plans. The patent drawing does not show deck details and in fact does not represent the vessel as built in any respect other than in being a catamaran with paddle wheel amidships between the hulls.

The _Steam Battery_ did not have any particular influence on the design of men-of-war that followed her. In the first place, steampower was not viewed with favor by naval officers generally. This was without doubt due to prejudice, but engines in 1820-30 were still unreliable when required to run for long periods, as experienced by the early ocean-going steamers. The great weight of the early steam engines and their size in relation to power were important, and also important were practical objections that prevented the design of efficient naval ocean steamers until about 1840; even then, the paddle wheels made them very vulnerable in action. Until the introduction of the screw propellor it was not possible to design a really effective ocean-going naval steamer; hence until about 1840-45, sail remained predominant in naval vessels for ocean service, and steamers were accepted only in coast defense and towing services, or as dispatch vessels.

No immediate use of the double hull in naval vessels of the maritime powers resulted from the construction of the _Steam Battery_. The flat-bottom chine-built design employed by Fulton in _North River_, _Raritan_, and other early steamboats was utilized in the design for a projected steamer by the British Admiralty in 1815-16. This vessel was about 76 feet overall, 16-foot beam, and 8-foot 10 inches depth in hold.

Her design was for a flat-bottom, chine-built hull with no fore-and-aft camber in the bottom, a sharp entrance, and a square-tuck stern with slight overhang above the cross-seam. Her side frames were straight and vertical amidships, but curved as the bow and stern were approached. She was to be a side-paddle-wheel steamer, and her hull was diagonally braced; the wheel and engine were to be about amidships where she was dead flat for about 14 feet. However, the engine and boilers were not installed; the engine was utilized ash.o.r.e for pumping, and the vessel was completed in the Deptford Yard as a sailing ship. Under the name _Congo_ she was employed in the African coast survey. Her plan is in the Admiralty Collection of Draughts, at the National Maritime Museum, Greenwich, England.

The double hull continued to be employed in both steam and team ferryboats in the United States and in England and France. A few river and lake steamers were also built with this design of hull. Continued efforts to obtain fast sailing by use of the double hull produced a number of sailing catamarans; of these the Herreshoff catamarans of the 1870's showed high speed when reaching in a fresh breeze.

Designs for double-hulled steamers appeared during the last half of the 19th century; in 1874 the _Castalia_, a large, double-hull, iron, cross-channel steamer, was built by the Thames Iron-works Company at Blackwall, England. She was 290 feet long, and each hull had a beam of 17 feet. The paddle wheel was placed between the hulls and, ready for sea, she drew 6-1/2 feet. She ran the 22 miles between Dover and Calais in 1 hour and 50 minutes, a speed much slower than that of the paddle-wheel, cross-channel steamers having one hull. Another double-hull steamer was built for this service by Hawthorn, Leslie and Company, Newcastle-on-Tyne, Scotland, in 1877. First named _Express_, she was renamed _Calais-Douvres_ when she went into service in May 1878.

Her length was 302 feet, her extreme beam 62 feet, and each hull had a beam of 18 feet, 3 inches. She drew 6-foot 7-1/2 inches ready for sea and the paddle wheel was between the hulls. On her trials she made 14 knots and burned coal excessively. Sold to France in 1880, she was taken out of service in 1889. Though popular, she was not faster than the single-hull steamers in this service and had been a comparatively expensive vessel to build and operate.

The many attempts to produce a very fast double-hull steamer and large sailing vessels have led to disappointment for their designers and sponsors. In the history of naval architecture, since Petty's time, there have been a number of periods when the new-old idea of the double hull has become popular. Craft of this type have been commonly well publicized but, on the whole, their basic designs have followed the same principles over and over again and have not produced the sought-for increase in speed and handiness.