Popular Science Monthly/Volume 58/December 1900/Submarine Navigation

From Wikisource
Jump to navigation Jump to search


By Professor W. P. BRADLEY,


IN a paper read before the Society of Naval Architects, Nov. 11, 1898, Lieut. Commander W. W. Kimball, who commanded the torpedo flotilla during the war with Spain, said: "If it be granted that the surface torpedo boat has a place in naval warfare, and that her primary duty is the attack by night upon ships attempting blockade or raiding operations, then most assuredly the submarine torpedo boat has a most important tactical place, since she, and she alone, is competent to deliver a torpedo attack by day upon ships attempting blockading, bombarding or raiding operations. She is the only kind of inexpensive craft that can move up to a battleship in daylight, in the face of her fire and in spite of her supporting destroyers, and force that ship to move off or receive a torpedo. That there is no physical difficulty in the problem, is amply proved by the accurate functioning of the boat now in this harbor (the 'Holland'), which has shown to scores of doubters that perfect control in both the vertical and horizontal planes has been accomplished, that the boat can be held at any depth to within a foot, and be made to take porpoise-like dives, exposing the conning tower for only six or eight seconds, and can be steered on any desired course."

Rear-Admiral Jouett testified before the Senate Committee on Naval Affairs: "If I commanded a squadron that was blockading a port, and the enemy had half a dozen of these Holland submarine boats, I would be compelled to abandon the blockade and put to sea, to avoid destruction of my ships from an invisible source from which I could not defend myself."

Lieut. A. P. Niblack, who commanded the torpedo boat 'Winslow' during the latter part of the war, wrote in 'Marine Engineering/ December, 1898: "The crowning virtue of a submarine boat is that it makes blockades almost impossible. Strategically in war, it has a place all to itself." He is authority also for the statement: "If Spain had had the 'Holland' at Santiago, the blockade of that port by the United States would have been impossible, within the radius of action of the boat."

Admiral Dewey testified before the House Committee on Naval A Hairs, April 23, 1900: "I saw the operation of the boat ('Holland') down off Mount Vernon the other day. I said then, and I have said it since, that if they (the Spanish) had had two of those things in Manila, I never could have held it with the squadron I had."

Rear-Admiral Philip Hichborn, Chief of the Bureau of Construction, writes in 'Engineering Magazine' for June, 1900: "Submarines can secure our coasts more perfectly than they can be secured in any other way at present practicable."

Mr. W. E. Eckert, consulting engineer of the Union Iron Works, of San Francisco, which built the 'Oregon' and the 'Olympia,' said, after the trial of the 'Holland' of September, 1899, in Peconic Bay, Long Island: "I have been on the trial trips of many of the new vessels built for the Government, and would say that I would feel safer in the Holland boat when under water than in the engine or fire rooms of any of the fast torpedo boats."

Rear-Admiral Endicott says: "The Holland submarine torpedo boat will revolutionize the world's naval warfare. It will make the navies of the world playthings in the grasp of the greatest naval engine in history."

However successful or safe submarine navigation may be to-day, the story of its development shows sufficiently that the risks to be taken have been very great, even though the actual loss of life incurred has been, on the whole, remarkably slight. To the venturesome spirits who have sought thus to master the ocean depths the risk involved has only added a new fascination.

The history of man's attempts to penetrate the depths of the ocean is not brief. The diving-suit, indeed, is modern, but the diving-bell appears to have been known in the time of Aristotle and diving itself is as old as man.

But essential mastery of the depths can never be attained by these means. The expert diver can remain below but two minutes or so, at the most. The tenant of a diving bell or suit is not, indeed, so limited in time, but, because absolutely dependent upon the flexible tube by means of which air is pumped down to him by companions at the surface, he is limited in space, and, by conditions of weather and sea, is limited also as to times. In no such sense is he independent as is the captain of an ocean greyhound or man-of-war, or even as the lone lobsterman at the helm of an undecked boat. To be master under water one must navigate under water, and any contrivance deserving the name of submarine boat must be able not only to sink beneath the surface, but also by its own power to move about under water for a reasonable time freely and independently. They who go down to the sea in suits and bells are not navigators.

The number of recorded attempts truly to navigate under water is surprisingly large. In a report of the United States Fortifications Board made in 1885 to the Forty-ninth Congress may be found a selected list of about fifty submarine boats. This list extends over a period of three centuries. It includes no boats which have been projected or described merely, nor even those which have been patented merely, but only such as had been actually built and practically tried up to that date. In the invention of these boats and in experimenting with them have been engaged the citizens of England, France, Holland, Spain, the Scandinavian countries, Italy, Russia and the United States—nearly all of the civilized countries. England has probably accomplished as little in this direction as any nation. France has shown by far the greatest zeal as a nation, and, on the whole, has been the most prolific. But the greatest practical success has been attained undoubtedly in our own country.

It would be a thankless as well as a wearisome task merely to enumerate the vessels of this list, still more so to describe them all, however briefly. Most of them were of ephemeral interest only. But there are some which should be mentioned in any account of submarine navigation, however concise.

Thus, in 1624 a Hollander named Cornelius Van Drebbell constructed a boat which was tried with some success in the Thames at London. James I. is said on one occasion at least to have been a witness of the experiments. But navigation under water in that day was an uncanny thing. Drebbell was regarded first as a magician, then as a madman, and then as an agent of the devil. Meeting no encouragement he died, and his secret died with him. It is curious to notice that Drebbell claimed to have discovered a certain fluid which possessed the power of purifying air vitiated by respiration. He called it 'Quintessence of Air.' From the standpoint of present knowledge this singular name and Drebbell's claim for the liquid are very suggestive. Oxygen was not discovered, as we believe, until a century and a half after Drebbell's time. But oxygen is the life-giving component of air. Moreover, volumetrically oxygen is the 'quintessence'—the fifth part—of air. Is it possible that Drebbell had discovered some liquid which easily disengaged the then unknown oxygen gas and thus was able to restore to vitiated air that principle of which respiration deprives it? Undoubtedly not. It is much more likely that he possessed a solution capable of absorbing the carbonic acid gas which is produced by respiration, and that the name given it was entirely fanciful and without special significance. But even if Drebbell's claim was a piece of pure quackery, with no substantial basis at all, it is nevertheless not without interest, for it shows, as we might have anticipated, that the problem of ventilation, one of the most important with which the inventors of submarines have had to deal, was at least appreciated by Drebbell the pioneer. In the latter half of the eighteenth century, an engineer named Day made one successful dive in the harbor of Plymouth, England, in a boat of his own designing. He went down a second time and did not return.

It may be said in general that the necessities and opportunities of war have always been the greatest, indeed, almost the only incentive to experiments under water. The War of Independence proved remarkably stimulating to submarine invention. In 1775 David Bushnell, of Connecticut, constructed a diving boat for use against English men-of-war. A minute description of this boat is contained in a letter written by him to Thomas Jefferson in 1787. It resembled externally two upper turtle shells joined together by their edges, whence its name 'Tortoise.' It carried a crew of one man, but this man was not David

Fig. 1. The Confederate Submarine Boat which Sank the U. S. Steamship 'Housatonic’ in Charleston Harbor During the Civil War.

Bushnell, as it appears! During the harbor trials the boat was connected with the dock by means of a rope so that it might be recovered in case of accident. David Bushnell manipulated the safer end of this rope on the dock, while his brother, Ezra, and afterwards Sergeant Lee, did their best to learn the proper use of the mechanism within.

The following year, the first of the war, Sergeant Lee steered the 'Tortoise' beneath the hull of the British ship 'Eagle,' of 64 guns, lying off Governor's Island in New York harbor. He attempted to fix to her bottom a torpedo by means of a wood screw, but being rather unskillful still in maneuvering the 'Tortoise,' he lost the 'Eagle' altogether and was finally forced to the surface for air. Daybreak prevented further operations at that time. Two similar attempts were afterwards made on the Hudson, but they also failed and the 'Tortoise' was finally sunk by a shot.

In 1800 Bobert Fulton, the father of steam navigation, built a very successful diving boat for Napoleon. It was called the 'Nautilus' and possibly suggested the theme of that fascinating story, 'Twenty Thousand Leagues Under the Sea.' By its use, he actually succeeded in blowing up in the harbor of Brest an old hulk which had been provided for the purpose. But Napoleon's favor proved fickle, and Fulton's success led to nothing further at the time.

Early in the Civil War the Federal government entered into negotiations with a certain Frenchman to build and operate a submarine boat against Confederate vessels. It was desired in particular to blow up the Confederate 'Merrimac' in Norfolk harbor. Ten thousand dollars was to be paid for the boat when finished and $5,000 for each successful attack with her. The boat was constructed at the navy yard at Washington and paid for, whereupon the wily Frenchman decamped with his money, leaving the government to learn the secret of running the craft. This they never did. In fact, it seemed the general opinion that even the Frenchman would have experienced some difficulty in so doing.

Much more successful were the Confederates. The following account is condensed from Admiral Porter's 'Naval History of the Civil War': On the 17th of February, 1864, the fine new Federal vessel 'Housatonic,' 1,261 tons, lay outside the bar in Charleston harbor. At 8:45 p. m. Acting Master Crosby discovered something about 100 yards away which looked like a plank moving through the water directly toward his ship. All the officers of the squadron had been officially informed of the fact that the Confederates had constructed a number of diving boats, called for some reason 'Davids,' and that they were planning mischief against the Northern navy. Moreover, a bold, though unsuccessful, attempt of four months before to blow up the Federal 'Ironsides' was fresh in the minds of all. When, therefore, the officer of the deck aboard the 'Housatonic' saw this object approaching, he instantly ordered the anchor chain slipped, the engines backed and all hands called on deck. It was too late. In less than two minutes from the time of first discovery the infernal machine was alongside. A torpedo carried at the end of a pole thrust out from the bow of the stranger struck the 'Housatonic' just forward of the mainmast on the starboard side in direct line with the magazine. A terrific explosion took place, and the 'Housatonic' rose in the water as if lifted by an earthquake, heeled to port and sank at once, stern foremost. The crew, who most fortunately had reached the deck, took to the rigging and were soon rescued by boats from the 'Canandaigua,' which lay not far oil'. The 'David' was afterwards found fast in the hole made by her own torpedo. She had been sucked in by the rush of water which filled the sinking wreck. Her crew of nine were all dead —killed doubtless not by drowning, though they must eventually have been drowned, nor as it would seem by suffocation, though in the end that would have followed; but probably by the concussion of their own torpedo.

The sublime heroism of these men is accentuated by the previous history of the 'David' to which they entrusted their lives. In her trial trip this boat sank for some unknown reason and her entire crew was drowned. Lieutenant Payne, her commander, escaped as by a miracle and succeeded in making his way to the surface. No sooner was the boat recovered from the bottom than he offered to try again. A new crew volunteered, and all went well for a time. But one night off Fort Sumter the boat capsized and four only escaped. The next essay was made under the lead of one of the men who had constructed the boat. This time she sank again and all hands were drowned. It was

Fig. 2. Goubet's Submarine Torpedo Boat.

such a boat, with such a history, in which that gallant crew of the 17th of February faced death and found it. North and South are united to-day as never before. We are permitted to treasure the memory of these brave men. They belonged to the same section as Hobson and displayed the same sublime heroism at Charleston as did he and his comrades at Santiago harbor.

The close of the Civil War marks an era in the history of submarine navigation. Previous to that time nearly all the boats were crudely designed and crudely built. Moreover, the nature and magnitude of the problems to be solved had not as yet been adequately understood. Whatever practical success has been achieved since is due to the fact that these problems have been thoughtfully and carefully studied, that those who have studied them have been in general better equipped therefor by education and training and have laid under requisition all the wealth of modern mechanical and physical science.

Of the many boats of this period, some of which have been quite successful, one may easily recall the French 'Le Plongeur,' the 'Gustav Zédé' the 'Morse' the 'Narval,' the Nordenfeldt boats and those of Goubet and Baker. Here also belong, of course, the latest and most successful boats of all, the 'Holland' and Mr. Lake's 'Argonaut,' of which some account will follow.

Turning now from the history of submarine navigation to a consideration of certain practical problems connected with it, we are brought at the outset face to face with a fact of fundamental significance, namely, that even with the aid of very powerful electric illumination it is not possible to see clearly through ordinary sea water for more than a few feet. According to Mr. Lake of the 'Argonaut,' about fifteen feet is the limit of visibility in our Northern waters, and about twice that in Southern. Submarine navigation is like navigation in the densest sort of a fog. High speed under water is just as possible mechanically as upon the surface. But the fact just stated is a death blow to high speed. Unless there shall be discovered some hitherto unsuspected means of perceiving at a distance invisible objects, high speed will unquestionably be fraught with great peril.

For the same reason it will probably be found impracticable to attempt very long journeys under water. There will probably never be trans-sub-atlantic lines, much less submarine greyhounds.

In fact, practical inventors of submarine craft, at least of late years, have ceased to attempt to provide more than a surface-going boat which shall be able at any time or place to dive beneath the surface to the depth desired, to remain under water for considerable periods of time, either stationary or moving, with both safety and comfort to the crew, and then, the purpose of the dive having been accomplished, to return speedily and safely to the surface. Even these requirements constitute a pretty large contract, but that they have been met satisfactorily appears sufficiently, so far as the 'Holland' at least is concerned, from the quotations given at the beginning of the article, and from the further fact that our government, ultra-conservative in adopting new devices for use in warfare, has purchased the 'Holland,' which is now at Newport in charge of Lieutenant Caldwell, Admiral Dewey's aid at Manila, and that Congress has authorized the building of six more 'Holland' boats of an improved type. Two of these are now being built at the Union Iron Works, at San Francisco, the rest at Elizabethport, N. J.

Obviously, a prime essential for any sojourn under water is an ample supply of pure air. When possible to make use of it there is but one rational source of pure air, and that is the exhaustless supply at the surface. Provided she herself secures it, a submarine boat does not in the least surrender her independence by utilizing this supply. This the 'Argonaut' does at ordinary depths by means of a pair of vertical tubes, one for inflow, the other for discharge.

The method answers very well for the peaceful commercial work of the 'Argonaut.' In war, however, this would usually he impossible. The 'Holland' in action must he entirely concealed from the enemy for considerable periods of time. The normal air capacity of her hull is, therefore, supplemented by compressed air tanks capable of withstanding pressures upwards of a ton to the inch, and of holding 4,000 feet of free air compressed into the volume of thirty cubic feet. These tanks are recharged by her own engines when at the surface.

Ever since the days of Drebbell's 'Quintessence of Air' a great deal of thought has been given to the problem of purifying the air once

Fig 3. The 'Argonaut' in Dry Dock.

vitiated by respiration and thus rendering it tit for use again. While it would seem to be a very simple task to restore from tanks or by chemical generation within the boat the oxygen which respiration consumes, and to absorb the water vapor and carbonic acid gas which respiration produces, those who have built the latest boats seem to have abandoned the attempt entirely. It is easy to imagine emergencies where fresh air could not well be obtained, and where such means of restoring air once breathed would be of prime value.

Objects under water are subject to pressure, which varies with the depth of submergence. At a depth of thirty-three feet this water pressure is about fifteen pounds to the square inch, or more than a ton to the foot. Solid construction is naturally in order for a submarine boat. But power to resist pressure depends also upon shape. A circular section, because it involves the principle of the arch, is the strongest. With a given thickness of metal, therefore, a spherical boat could safely dive deeper than one of any other form. But the exterior of such a boat is ill-adapted to propulsion, and the interior for the arrangement of machinery.

Since the days of Captain Nemo and the fabulous 'Nautilus' the cigar shape has doubtless been associated with submarine navigation in

Fig 4. The 'Holland' in Dry Dock.

the minds of ninety-nine out of every hundred persons who have thought of the matter at all. And it is equally a matter of sober history that this form has been almost universally adopted. Some inventors in the earlier days, with the vision of high speed in mind, have trimmed down the lines to almost needle-like fineness, as in the 'Gustav Zédé.' Now that attempts at high speed have been abandoned, the elongated spheroidal or egg-shape is the favorite, as illustrated both by the 'Holland' and the 'Argonaut.'

But what of power for locomotion under water? Obviously steam power, at least as ordinarily produced elsewhere, will not do. Even supposing the necessary draft to be secured, how shall the smoke be concealed, and how shall the crew endure the excessive temperature to which coal fires with little ventilation would subject them? Fortunately, the problem of power for propulsion is much simplified by the fact already mentioned, that for the most part, even a submarine boat lives and moves and has its being on the surface. When at the surface, steam power may be used as on any boat. Many of the earlier boats were thus equipped with boilers and steam engines. These served not only for surface propulsion, but were used also to store up

Fig. 5. Sketch of the 'Argonaut' as She Might Appear at the Bottom of the Sea.

energy in the form of electricity or compressed air to be available as power when diving.

Nowadays gasoline and oil motors have been so perfected and they allow such economy of fuel space and withal such freedom from the dust, smoke and heat incident to a steam plant that they are coming into very general use, both afloat and ashore, where moderate amounts of power are required. Both the 'Holland' and the 'Argonaut' are equipped with gasoline engines. As these require for their operation much larger quantities of air than can be conveniently supplied from compressed air tanks, wherever concealment is necessary and a supply of air from the surface is out of the question, recourse is still had as before to some form of storage power for propulsion. At present this is always electric.

The problem of diving demands attention next. For surface sailing a submarine boat, like any other, needs considerable buoyancy, so as to float with a considerable fraction of its bulk free above water. For diving, on the other hand, her buoyancy must be very small. These conditions are met by varying the amount of ballast carried. This is universally done by admitting water into, or expelling it from, suitable air-tight tanks distributed through the bottom of the boat. The filling of these tanks requiers only the opening of a valve. To empty them

Fig. 6. Photographs of a Trial of the 'Holland,' showing her in Cruising Trim, in Diving Trim, Diving, and Rising after the Dive.

requires power. Formerly this was done by means of pumps. But pumping is slow work. A much more expeditious method of emptying the water tanks is to blow out the water by admitting compressed air from the reservoirs. The air so used is finally delivered into the living rooms for breathing, and the pressure in the reservoirs is restored again win n at the surface. By thus varying the quantity of ballast a boat may be caused to sink, or, if already beneath the water, be caused to rise to the surface either slowly or rapidly as may be desired. It is easy to imagine circumstances, either accidental or otherwise, where a very sudden return to the surface might be imperative. To provide for this in emergencies the most practical boats are furnished with a very heavy false keel of iron, which may almost instantly be detached by the throwing of a lever or the turning of a screw within the boat, The effect is precisely the same as that produced by throwing out a large quantity of ballast from the car of a balloon.

To sink a boat, take on sufficient ballast; to rise, discharge ballast, as, in a balloon. But the ballast that will sink a boat beneath the surface aft all will sink her to the bottom, and on the other hand if ballast be-discharged until the rise begins, the rise will continue till the boat is, again at the surface. To regulate the depth of submergence, therefore, something more is needed than mere adjustment of ballast. Practically there are but two ways of securing this regulation. One, represented

Fig. 7. Cross Section of the 'Holland' Amidships.

in the Nordenfeldt boats and in some others, depends on the action of propellers arranged to act vertically instead of horizontally as do the ordinary. Although this method has the advantage of being applicable whether the boat is progressively in motion or not, it is now entirely abandoned. No sane person would advocate lateral propellers for moving a boat to right or left, and the disadvantages of vertical propellers for vertical motion are of the same order. The 'Holland' dives, rises or runs at a constant depth by the use of a rudder at the stern set at right angles to that for steering to right and left. By means of this rudder in the hands of a skilled steersman the 'Holland' can be held for a mile or over to within less than a foot of any depth desired.

As may be inferred from the quotations at the beginning of this article, the 'Holland' certainly embodies the highest attainments ever made in a submarine war vessel. In the words of Rear Admiral Hichborn, "The 'Holland' is an improvement upon anything that has ever been built in the history of the world." She is fifty-four feet long and is able with her forty-five H. P. gasoline engines to run considerably more than a thousand miles on the surface without recourse to any base of supplies, and, with her storage batteries and electric motors, thirty miles under water. Her offensive equipment is represented by an expulsion tube and three Whitehead torpedoes.

Her plan of operations when in the presence of a hostile vessel is to dive beneath the surface and steer by compass straight for the enemy. At intervals of a mile or so she rises till the top of her conning tower only protrudes, corrects her course and dives again. An emergence of eight to ten seconds only is required. Having arrived within a few hundred yards of the enemy the 'Holland' emerges for the last time, fires her torpedo, dives, turns back on her course and runs home.

During all this time she is perfectly protected by her invisibility. Even when rising she exposes so small a surface and that so low in the water that the chances are all against her being detected at all, especially as no one can tell when or where she will appear. Or if seen by the enemy there is no time to train guns upon her, and if there were, the chances are infinitesimal that so small an object could ever be hit. On the other hand, no defensive armor could save from absolute destruction a vessel once hit by the 'Holland's' torpedo.

After all is said which may be, of the terribly destructive power of the 'Holland,' or of any other submarine boat, it seems unquestionable that the greatest argument in favor of her adoption into a navy is not based thereupon, but rather upon the moral effect which would follow the knowledge that a nation possessed such a boat at all. "There is nothing more terrifying and demoralizing than to be attacked by an invisible foe; nothing more trying, bewildering and ineffective than striving to answer such an attack." If a captain of a battleship should see the turret of a submarine appear at the surface, straighten her course toward him, and then in ten seconds, before a shot could be fired, sink out of sight again, what would be his duty as a brave man, charged with responsibility for millions of property and hundreds of lives and with the performance of effective service for his country? To seek means of defense? There is no defense but flight, swift and immediate.

Hostile transports especially would not dare to approach a coast where the proximity of such a boat was suspected. High authorities insist that blockading also would be impossible if a harbor contained half a dozen of these terrible engines, which strike where no armor can afford protection, which come one knows not whence nor when, and which are invulnerable because invisible. Any nation suitably equipped with such means of defense would be impregnable on the side of the sea.

Every submarine boat with a single exception, so far as the writer knows, has been designed solely or at least chiefly with reference to use in war. That exception is the 'Argonaut,' designed by Simon Lake and owned by the Lake Submarine Company.

The 'Argonaut' is intended for peaceful pursuits and is built and equipped accordingly. Her purpose is to save property, not to destroy it. Hit work is to be quiet and prosaic, but none the less efficient and valuable. The success of her inventor and his company depends not upon the favor of governments and department officials, but upon the successful performance of forms of work which have a direct commercial value.

Fig. S. Longitudinal Section of the Submarine Boat 'Argonaut.'

She is built to travel on the bottom and is provided accordingly with wheels like a tricycle. Except in war, there is scarcely a single valuable object which can be served by navigation between the surface and the bottom. The treasures of the deep are on the bottom. On the bottom are the sponges, the pearls, the corals, the shell fish, the wrecks of treasure ships and coal ships and the gold-bearing sands. On the bottom are the foundations of submarine works, explosive harbor defenses and cables. To the bottom the ’Argonaut’ goes, and on it she does her work.

Propelled at the surface by her gasoline engines, she looks much like any other power boat. The upper part of her hull is that of ordinary surface-going boats. Underneath she has the ovoidal form. Conspicuous on her deck are the two vertical pipes by means of which during submergence fresh air is drawn from the surface and the vitiated air within expelled. On the deck are also a derrick and a powerful sand pump for use in wrecking or in Submarine construction, while a powerful electric lamp in her conical under-water how illuminates the field of her operations. Most interesting is the sea door at the bottom forward, through which divers enter and leave the boat when on the ocean floor, the inrush of water into the diving compartment being prevented in the meantime by air pressure within, equal to and balancing the water pressure without. The 'Argonaut' has already traveled, it is said, hundreds of miles on the surface and scores on the ocean

Fig. 9 Cross Section of the 'Argonaut' Amidships.

bottom. She can remain at the bottom as long as her gasoline and provisions hold out, with no other inconvenience to her crew than is occasioned by the somewhat restricted room within.

Mastery is the motto of mankind. Instinctively the race is ever obedient to that ringing commission of the Omnipotent: "Replenish the earth, and subdue it—and have dominion." Man longs to explore every unknown realm. He thirsts for knowledge, which is power, and by it he masters the mighty forces of nature and makes them his servants. It seems a little thing to have dominion over the habitable portions of the earth—he must search the stretches of the desert, the realms of frost and eternal snow and the expanse of the sea. It is not enough to know the length and breadth of the earth—he must scale the heights of the mountains and penetrate the secrets of the great deep. Alexander weeping because, as he thought, there were no more worlds to conquer, is an ancient type of that same masterful spirit of which Kipling is the mighty modern prophet. But modern Alexanders find no place for tears.

According to competent judges, the submarine is to-day ready to serve mankind; the 'Holland' to make war less popular, the 'Argonaut' to make peace more valuable.

We should take genuine pride, should we not, in the fact that citizens of our own country are to-day foremost in the construction and use of these mighty engines?

Fig. 10. The 'Argonaut' Submerged.