Monday, 18 July 2011


The idea of floating airports has been around for a very long time in one form or another and   some still believe the idea could provide a solution to a region’s air traffic problems. Here I look at the history of the Seadromes concept and how they continue to be a consideration.

Below: Diagram for the proposed floating airport near Schipol

In July 2007 various publications reported a two-year old proposal by a far-thinking Encinitas, California lawyer who was attempting to revive the idea of offshore floating airports. The company he formed, Ocean Works Development planned to build a 2000 acre platform, costing US$20 billion, 10 miles off the San Diego coast at a point where the Pacific is 350 to 1000 metres deep. The idea was the brainchild of Cambridge educated Adam Englund who intended to install a superstructure in the style of a massive oil rig, with a pair of unobstructed runways. Englund claims to have gathered a team of forty collaborators consisting of ‘pilots, naval architects, maritime engineers and finance types’ to support the project known as O-Plex 2020. The elaborate plans include the main landing platform above four dedicated decks to provide hotels, shops, restaurants, conference centre, research facilities – even a university. The structure has been devised to offer real estate space covering an area of 200 million feet².  The idea was fired by the San Diego Airport Authority’s failure to find a suitable site to build a new land based airport.  At the time Englund said: “the offshore option is the best and apparently the only viable one for San Diego.” A number of experts agreed that the plan was workable, among them an oceanographer who believed ‘a floating airport is every bit as achievable as putting a man on the moon.’ The project of course also has its critics who consider the idea to be more delusionary than visionary.

Englund visualised his grandiose scheme more as a green city; a project that would harvest wind and wave energy, and in a far reaching plan would include pumping clean water back to the mainland using a massive desalinization plant. He said he had no plans to seek government funding preferring to finance the airport from private investment; nevertheless the Interior Department formally challenged OceanWorks’ claim to use the US Exclusive Economic Zone for Airports without offering a reason. Initially it seemed unclear which Federal agency, if any, would have ultimate responsibility for approving the building of a major airport in a swathe of ocean, the Army Corps of Engineers appeared to claim this. 

Logistically the problems of a facility of this kind would appear difficult and extremely costly especially for the safe transference of aviation fuel and passengers. Englund proposed to provide land based terminals dotted along the Southern California coast to connect with the airport using fast ferries. There was also a plan to link the terminal at Lindbergh Field with the offshore airport using a light railway that would run in an immersed tunnel or Archimedes bridge* 100 feet below the ocean surface. Publicity has prompted considerable debate over whether the airport would be feasible to build. But in July 2009 the San Diego County Regional Airport Authority announced its own $1 billion Green Build plan to develop the western side of Lindbergh Field.  Ten more gates will be added at Terminal 2 West allowing an average of 60 extra flights a day to use the airport. Passenger facilities and taxiways will also be improved and there will be better overnight parking for aircraft. A groundbreaking ceremony took place in July 2009 and work on the expansion project is expected to continue into 2012 and will be the largest project in the history of San Diego International Airport. Although this will help solve some problems in the short term, critics say much more needs to be done to relieve future congestion. Other options are being studied to consider the air transportation needs over the next 30 years and beyond. In a scheme known as the Ultimate Build Out, an intermodal Transportation Centre is proposed for the north-east side of the airport. While land for development remains scarce The OceanWorks project might still provide an answer to the region’s future air traffic problems and currently Englund is undeterred by his critics and is trying to raise the finance  for his project. 

Offshore airports, although not a new idea, continue to interest planners and in the 1960s Los Angeles had considered a proposal for a floating airport to replace LAX. But so far, the few offshore airports already in existence including Kansai, Kitakyush, Kobi and Chuba in Japan and Hong Kong’s Chek Lap Kok have all been constructed using landfill to build artificial islands in preference to floating platforms. Since the 1970s there have also been several proposals, still at times revived, to build an offshore airport in the Thames estuary to cope with the increasing demands on London’s vastly overcrowded airports. But the Dutch Government has been more proactive in their consideration to approve an offshore floating platform. Invented by Van Den Noort Innovations NV in conjunction with Royal Haskoning Technical Engineering, Van Oord and the Technical University of Delft (Holland), the idea is to develop a rotating floating airport to ease the strain on Amsterdam’s Schiphol. With an estimated build cost of €90 billion (US$132 bn), this ambitious concept is considered to be more cost effective and efficient than constructing a new airport on an artificial island, although the idea owes some of its innovation to knowledge the designers gained from their work on offshore developments such as the Palm Islands in Dubai. The airport involves a purely afloat platform with two parallel runways designed to revolve 360 degrees around a fixed control tower. This would have the advantage of permitting aircraft take-off or land into the wind all of the time.  The proposal is to locate the airport approximately 20 kilometers from the Dutch coast with passengers being transferred to a departures/arrivals facility, built onto the sea floor, via a tunnel from the Schiphol terminal by rapid transit trains using magnet levitation technology.

The original idea of a floating airport began in 1913 when Canadian born, Edward Robert Armstrong (1876-1955) invented the Seadrome. Armstrong, a circus strong man in his younger days, had worked in the early automotive and aviation industry and took his inspiration for his inventive mind from Jules Verne, his favorite author. His idea started to develop after he joined Du Pont de Nemours Co of Wilmington, Delaware as a research engineer.  In the absence of suitable aircraft capable of flying passengers and freight across the Atlantic, Armstrong drew plans for a structure, not dissimilar to an offshore oil rig that would provide runway, maintenance and passenger facilities at a string of up to eight floating platforms. These were to be located at 350-400 mile intervals across the ocean between the US and Europe.  Various changes were made to his initial proposals during the 1920s. By then Armstrong had been appointed chief engineer at Dupont and in his role as a senior executive was encouraged to develop his idea further. He reasoned that as sufficient sea traffic was already crossing the Atlantic, this would support his plans for engineered islands allowing aircraft to land and refuel and for passengers to rest and socialize between the continents. By 1921 he had completed a thorough feasibility study that included investigating sea currents, storm frequencies, fog conditions, wind patterns and the depth and geology of the ocean floor. His proposition was not only accepted as feasible, but in some academic quarters recognized as a ‘masterpiece’.  

Based on the success of the large naval aircraft carriers Saratoga and Lexington, Armstrong planned to build massive platforms weighing 15,000 tons and measuring 1200 feet in length by 400 feet at the widest point where the main deck accommodation would be located.  He structures would include a hangar with maintenance facilities; staff quarters and a 40-room luxury hotel for passengers.  The latter would have provided facilities equal to, or more comfortable, than those provided on existing ocean going steamers. Armstrong also believed that, by locating the Seadromes in international waters under the British flag, the US Prohibition Laws in force at the time could not be applied thus allowing passengers to enjoy the bar and gambling facilities he proposed to include that would operate unimpeded by government interference.

The platforms were designed to stand on sturdy columns, 270 feet tall that would contain buoyancy chambers and ballast tanks with the main landing platform 70 feet above the ocean, high enough to be safely beyond the reach of the largest Atlantic waves. Armstrong had reasoned that by placing 95% of the structure’s weight below sea level would provide complete stability even in the heaviest seas.  As the ocean was up to three miles deep, anchoring the platforms presented a formidable drawback. He found a solution by devising 125-ton buoys with galvanized steel cables 2.5 inches in diameter that would be attached to anchors weighing six tons. The cables were initially designed to be five miles long, but later reduced to 3½ miles by increasing the anchor weight pro-rata to 15 tons. 

Armstrong was given leave by DuPont to work full time on the project. He formed the Armstrong Seadrome Development Company that originally proposed to construct a test rig in early 1928, destined to be built by H H Ward of Chester, Pennsylvania that had been intended to anchor 350 miles from New York. He announced, rather prematurely as it turned out, that trans-Atlantic flights would commence using the Seadromes in 1930. But the planned test rig was never completed; instead a 1/32 scale model was built in October 1928 on the Choptank River estuary at Chesapeake Bay, a part of the Dupont estate, that weighed just over a ton and had a length of 35 feet.

The Sun Shipbuilding Company of Chester and the Belmont Iron Works of Eddystone, Pennsylvania were ready to commence building the first full size Seadrome that by December 1929 had increased in weight to 29,000 tons. Several other contractors became  involved with to construct cables; to carry out route studies and other aspects of the development, but the estimated $2 million estimated build cost of the project seemed rather optimistic considering the amount of work involved. The first platform was to be constructed off Cape May on the Delaware River from where it would be towed to a location between New York and Bermuda. However, the opening date had to be put back to May 1932 after construction had failed to go to plan and the escalating build problems needed to be solved.  These included adding a rudder into the design to control yawing and by introducing heavy winches to control cable tension particularly during calm seas after the model had demonstrated a tendency to drift towards the surface buoys. It appears the company was also undergoing some financial and operational problems that led to a parent company being formed called the Seadrome Corporation which had a subsidiary known as North Atlantic Airways that intended to raise money from shareholders. By then the proposed number of Seadromes was cut to reduce costs with the Azores added as the final ink to Europe with likely landfall destinations named as Brest, Lisbon and Vigo. But the project continued to be overstretched, both in time and money. When the proposed airway was due to become operational aircraft development had already progressed. Pan American Airways was already working with Sikorsky to build the S-42, a flying boat with a range of 750 miles that would seriously limit the viability of the Seadromes. When the Wall Street crash occurred in October 1929 this threw a further spanner in the works and Armstrong’s project was rapidly running out of cash. 

The model tests had indicated that the horizontal and diagonal cross bracing designed to provide extra strength to the 32 support pylons would not be necessary. Although this translated into considerable weight and cost savings, the anchoring system presented further difficulties that had not previously been predicted.  By January 1931 new plans were revealed for a massive spherical shaped anchor made from reinforced concrete that would be 100 feet in diameter and weigh 1,500 tons. Chains were also incorporated within the design to provide the extra strength the cables needed to secure a Seadrome in place.  The overall weight of each platform had also snowballed from the original 15,000 to 47,000 tons with the estimated cost of the project spiralling out of control to more than $93 million. Armstrong’s projected operating costs had also escalated from $26 million a year to $54 million. He had optimistically based the annual returns for the Seadromes on   170,000 passengers arriving on the platforms on ten daily Sikorsky S-40 flights carrying 30 passengers each. This was wildly unrealistic, particularly considering that the world was in Depression and that only the rich could afford the high cost of air tickets. But Armstrong refused to let go of his belief in the viability of his project. He applied for US Government backing but after early rejections his idea reached President Franklin Roosevelt in 1934. Armstrong was invited to make a presentation to the Federal Aviation Commission (FAC). Charles Lindbergh, who had earlier supported the Seadrome concept, by then was working for Pan American Airways, testified against Armstrong’s project in the realization that if it were allowed to progress it would pose a direct threat to the aircraft Pan Am was having built. This effectively scuppered the Seadrome project before it was built.

But Armstrong’s dream was not quite dead and buried. The flamboyant Chairman of Pennsylvania-Central Airlines, C Bedell Monro, still believed in the credibility of the idea and attempted to revive it during 1943. By then the operating range of aircraft had increased with the introduction of the Douglas DC-3 and DC-4E prototype (first flown 1938) reducing the potential number of Seadromes   for an Atlantic crossing to three, each weighing less (estimated at 64,000 tons) and costing $10 million. Juan Trippe had no interest in Seadromes; Pan Am was already successfully flying the Atlantic with their Boeing 314 flying boats and the Boeing 307 had also crossed without the aid of ocean based platforms. Trippe’s Pan American empire was expanding at a gallop, and his vision of the future was not in the use of sea based airports but in bigger and better aircraft capable of conquering vast distances non-stop. He was right; but although Edward Robert Armstrong, still clutching at his vision, slipped into oblivion the idea of floating seadromes has remained to stir the imagination. Some of the technology Armstrong had been developing was later used in semi-submersible oil drilling platforms.   

In a rather intriguing twist to this tale, Bruce Figarsky, a man who described himself as someone with a passion for aviation, claims to own the Armstrong’s personal portfolio of papers connected to the Seadrome. This, according to the American television series ‘The History Detectives’ includes a blue print drawing dated 1937 and a portfolio of articles from magazines from the US and other parts of the world. Figarsky told the programme that he bought at a flea market in Lincoln, Nebraska while on a drive from California. How they got there nobody knows but the ‘find’ is featured in a video from the television series that can be seen online at: ( During my research of this article I attempted to contact Mr Figarsky on several occasions but I received no response to my emails. 

*An Archimedes bridge is a submerged floating tunnel that is supported by buoyancy and held in place by anchors and steel cables to the seabed or pontoons. It is so called because it uses Archimedes theory ‘that an object immersed in fluid loses weight equal to the weight of the amount of fluid it displaces.’  The Italian company, Ponte di Archimedes International is planning to build the first prototype bridge at Qiandao Lake in the eastern Chinese province of Zhejiang.

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