"Seadromes": an Idea Whose Time Never Came

       In 1844 Edgar Allan Poe produced a short story about a balloon crossing the Atlantic in three days. Fast forward a century, and we discover that balloons are out of fashion, but commercial transAtlantic flights by aircraft are still in their infancy. The first such flight, by Lufthansa, took place in 1938, and lasted 25 hours. You can immediately see a problem: compared to today, flights were much slower and, unlike balloons, required copious amounts of fuel. Also, there existed other, longer stretches of ocean. The first commercial transPacific flight may have been in 1935, but it involved a series of island hops. Nevertheless, a solution had been suggested for the problem: just as aerodromes were scattered all over the land, it might be possible to scatter the sea with marine aerodromes, or "seadromes" as they were called. Much later, the concept was used to produce floating oil rigs but, basically, it was an idea whose time never came. For your information, nevertheless, I shall introduce you to this forgotten topic by reprinting an essay from the same 1939 British boys' magazine as in my previous article.

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The Romance of Modern Invention. Seadromes

by W. B. Home-Call

Chums (1939), pp 306-7

     Will the great seas of the future be dotted with seadromes, just as aerodromes blaze trails across the land from North to South Africa, across Asia, and through to Australia? Jungles have been cleared to form aerodromes, and like artificial oases they have sprung up in the middle or on the edges of deserts. Thus is a flyer across land guarded, as far as possible, from the danger of being stranded miles from refuelling stations.

     The seadrome is claimed by its sponsors to be the obvious and necessary equivalent on flying routs over vast seas. To many a seadrome is a thing to be laughed at. Unfortunately, our own Government sides with the scoffers. In March, 1937, Commander Locker-Lampson asked if money could be set aside for research work in connection with seadromes. He was told by Sir Victor Warrender, Financial Secretary to the War Office, that seadromes were not considered to be of sufficient use to warrant money spent on them in research.

     As a representative of the War Office, Sir Victor's answer can be understood. A seadrome in mid-Atlantic might not help us very much in the event of a European War. But a member of a more peaceful department should have replied, and it is unlikely he could have dubbed them as being of doubtful utility, especially if he considered the action that has been taken towards seadromes by the United States Government.

     In 1934 the Seadromes Ocean Dock Corporation applied to the U.S. Department of Public Works for a loan of £7,200,000 [worth £522.6 million, or a billion dollars, in 2020] to enable them to build five seadromes to be placed at 500-mile intervals across the Atlantic, to connect America with the British Isles. The U.S. Department of Public Works referred the matter to the U.S. Navy Department, who thoroughly tested models of the proposed seadromes, and were so satisfied with the result of those tests that they advised the immediate loan of £1,600,000 to enable the first seadrome to be built, and placed on the existing New York to Bermuda air route.

     The seadromes tested were made by the Armstrong Seadrome Company, and as already stated, it is considered that five will be a sufficient number to link England with America. Each seadrome would be 1,500 feet long and 300 feet in breadth at its widest point, which would be in the centre of the sea-aerodrome. The seadrome would be roughly bottle-shaped at both ends, the breadth at its ends being about 150 to 200 feet. There would be hotel accommodation beneath a flat, unobstructed flight deck so in the future people wishing for a healthy and quiet holiday will probably spend a few days at a seadrome hotel, surrounded by hundreds of miles of sea in every direction. On the lower decks there would also be radio and meteorological stations, hangars and workshops. A crew of 43 would man a seadrome, and probably work in shifts of one month.

     The marvellous feature about a seadrome is that they can be constructed so as not to rise and fall with the waves. The flight deck is the only part above the normal sea level, the remainder of the huge floating island is not only below sea level, but below the level of both the waves and the trough between the highest waves, i.e. below the agitated surface of the sea.

     The flight deck is supported on thirty-two streamline pillars, which lift it 103 feet above sea level. Their buoyancy and ballast chambers are so designed that the centre of buoyancy and gravity of the whole seadrome structure are below the agitated surface of the ocean. Thus no matter how rough the sea, the seadrome remains floating in suspension beneath the surface motion of the waves and has no tendency to roll or pitch. These pillars, or buoyancy units, are of such shape and spacing in the structure that they offer practically no resistance to the waves, and so do not interfere with their passage.

     No energy is released from the waves, and therefore the fact that the huge Atlantic liners have come to port with their bows or sides battered in by gigantic rollers of mid-Atlantic storms, does not jeopardise the chance of the seadrome to live, unaffected, through one of those storms. The liner floats on the surface of the waves. A seadrome floats beneath the largest of waves, which pass through its pillars like waves pass unbroken through the supports of a pier.

     In testing laboratories films have been taken of model of a seadrome and model of the Majestic, both made correctly to scale. The Majestic is seen wallowing in waves, water splashing over its bridge decks. The seadrome rides steadily, unaffected by the surface disturbances. A seadrome model one-tenth scale and 30 feet in height underwent most strenuous tests in a U.S. Naval Dockyard basin and scarcely moved, whilst a man in a rowing boat near by was almost capsized by the manner in which the water was disturbed.

    A novel type of anchor has been designed to keep the seadromes in position. It is round on the top and flat underneath, and weighs 1,500 tons. Buoyancy chambers permit it to be floated to the correct position; seacocks will then be opened electrically and the buoyancy chamber will be flooded. The rate of descent of the anchor will be checked by means of water-brakes, and the landing shock will amount to only 15 percent. of the anchor's weight. The U.S. Navy Department have tested this anchor and are completely satisfied that it can be lowered and can be relied upon to keep a seadrome in position. When once at the bottom of the ocean, the flat face of the anchor, sinking into the ooze, will substantially make the anchor a part of the ocean bed, and subject to the pressure of the overlying water, thereby in effect increasing its friction and resistance to movement.

     The weight on these anchors may be as great as 750,000 tons at the deepest parts where they have to be dropped, and there will be, therefore, quite immovable by cables. The calculated tension on the cable is expected to be 100,000 lbs., but cables are to be used which will stand a strain of 200,000 lbs. The strain is occasioned, of course, by storms, wind and currents. 200,000 lbs. will allow of storms of 140 miles an hour - twice that of the maximum known speed of a storm in that latitude. In addition, each seadrome is fitted with four screws capable of a thrust of 100,000 lbs. Normally these motors are for manoeuvring the seadromes, but they can be used to relieve the strain on the cable by being put into motion so that they thrust the seadrome "into the storm."

     The seadromes may have to be moored at depths as great as three or four miles. The strongest chains even made would break from their own weight before they were lowered to 1,300 feet. The special cables to be used in the case of seadromes are suspension-bridge type. They can be lowered to a depth of 60,000 feet, which is considerable beyond the depth of the deepest ocean.

    Corrosion has been accounted for, too. The cable used will not corrode. Lloyd's have tested the cable and are so satisfied that they are willing to insure the seadromes at a charge of only 2 per cent. Two 85-year-old ships with underneath plates of iron were examined when material for a suitable cable was being sought, and even after eighty-five years the iron showed no sign of corrosion. Barnacles are not expected to form on the cables of the seadrome. Barnacles, it has been discovered, only form on ships in warm weather. The cold Atlantic water will produce no barnacles.

     The seadrome is moored to a buoy, rather similar in construction to itself, so as to defeat the surface agitation of the sea. The buoy is moored to the artificial rock or anchor. The buoy, therefore, can bob up and down, and yet the pull of the cable from the buoy to the seadrome will remain practically horizontal, and therefore not tug the seadrome.

     The seadrome will have many uses other than being a landing 'drome for aerodromes. Crippled ships, for example, can be docked in floating docks on the seadrome. A remarkable invention enables the sea round the seadrome to be calmed to permit this operation. Compressed air, pressed through perforated pipes sunk horizontally to a small depth below the surface of the waves, is employed. The air rises swiftly through the water and causes excessive turbulence. Oncoming waves meet this wall of turbulence and miraculously subside. Oil merely smooths the surface without dispersing the waves, but the wall caused by compressed air makes waves absolutely vanish. It sounds incredible, but it is a fact. Without the used of this method, a boat, bobbing up and down on waves, can be moored to a seadrome by means of a connecting apparatus known as a "bosun's chair". This allows of expansion and contraction by connecting cable and, of course, does not keep the boat still.

     Seadromes are built in docks like sea vessels. The pillars, or caissons, as bridge builders would call them, are built separately, presumably horizontally.  They are set upright in docks, and the seadrome is assembled in sections, and fitments are added just as the engines and interior fittings of liners are added to a ship while it is in dry dock. Each section is floated separately, and as many sections as desired are joined together by cross-girders. Thus a seadrome can be made any size. A seadrome costs no more to build than the iron skeleton of any of London's large buildings, and not nearly as much as New York skyscraper's skeleton.

     The life of a seadrome is estimated at, at least, 20 to 40 years, and probably considerably longer. Statistics by the U.S. Hydrographic Department and Weather Bureau suggest that the 38 parallel of latitude will be the best in which to anchor the seadromes. It is too far south for icebergw; fog averages about two days a year in that latitude, and gales have never been known to exceed seventy miles an hour there, or sea currents to exceed 1½ knots.

     The seadromes are expected quickly to become a paying proposition. Toll is proposed for aeroplanes using the seadromes at the rate of £14 per passenger for the complete set of seadromes, 7d. per lb. for parcels, and 2½d. on each letter. [In 2020 equivalents, these amount to £887, £1.84 and 51p respectively. Double them for approximate dollar values.] The heavy cost per lb.-mile of steamship operation will enable aeroplanes using seadromes, to be much cheaper. Not only does a liner like the Queen Mary or the Normandie cost as much as the whole Transatlantic system of seadromes, together with a fleet of airlines, but the Queen Mary and the Normandie are expected to run at a considerable annual loss. 

      A seadrome, built in America, costs £1,600,000. Built in England, it could be constructed for a very much less figure, probably only a little over £1,000,000.

      Airships could not stand the competition of aeroplanes. Although an airship carries 50 passengers, it only travels at a speed of eighty miles an hour. Dr. Eckner himself has said he would require five airships to maintain a service of twice a week across the Atlantic. The cost of five airships would be £1,750.000, and even they, doing a bi-weekly trip each way, could only carry 200 passengers a week. A fleet of thirty aeroplanes would cost much less. They could maintain a two-hourly service, could carry over 1,000 passengers a week, and as they travel at 200 m.p.h., could allow those passengers to travel from London to New York in twenty-four hours, as against the airship's three days and the Queen Mary's five days.

     If there were real islands in the middle of the Atlantic, any nations would willingly pay £1,000,000 each for them. The island route via Shetlands, the Faroes and Iceland is not practicable owing to fog and ice. There is also the Azores and Bermuda route, marred by continuous ground swell off the Azores and the mountainous nature of both islands. Furthermore, terrific hurricanes sometimes occur between Bermuda an America.

     The alternative to seadromes are catapult ships [aircraft carriers]. Catapult ships experience difficulty in lifting a seaplane from the sea in rough weather. But there is another objection against catapult ships which an official of Imperial Airways explained to me. When an aeroplane is catapulted, the back of the pilot's neck has to be very heavily padded to protect him from the terrible jerk forward that is necessary to give the plane the necessary flying speed. How would a cabin-full of passengers be protected against that?

     The position of seadromes in existing international law is as follows:-

     "The construction of seadromes, or floating islands as they are commonly called, may be legitimately be undertaken by any state or any private individual, provided always that the latter is under the authority of a state. There is nothing against the construction of seadromes by a state which does not possess a maritime frontier. The construction of these seadromes, and the conditions of access and operation, should be such as not to interfere with navigation, either maritime or air. All conditions relating to the special legal position of these seadromes, both in time of peace and in time of war, shall be those applying to ships, with the exception of any special regulations fixed by international agreement."

     In conclusion, it should be remarked that these floating islands should not be called seadromes. A car park is a park for a car whether it is in an inland town or at the seaside or even on a boat for that matter. A landing ground for aeroplanes is an aerodrome - whether on land or floating on sea. Seadrome, translated literally, means a "drome" for the sea! A sort of playing-ground for waves! It is probably too late to change the name now - look at seaplanes! The name sounds like a motorboat. A seaplane is an aeroplane. It spends as much time in the air as an ordinary aeroplane. If anybody started talking of land-planes, we should imagine a machine that whizzed along a few feet above the ground. We'd never think of looking in the air for it!