April 17, 2009 For most of us, the world deep below the ocean’s surface remains a place we have only had the pleasure to experience vicariously, primarily through watching nature documentaries. It's not as if we can just hop in a submarine and go take a look. Well, perhaps we can, if a Russian company's plan to market a two-seater submarine driven by pedal power to the tourist industry is successful. The new underwater vehicle (UV) from Marine Innovation Technologies (MIT) will not only be cheaper to buy and run than existing submersibles, it will be simpler to operate, requiring no special training or expertise.
According to MIT, its underwater craft differs from comparable small tourist submarines in overcoming some of the difficulties associated with the use of traditional screw propulsion and accumulator batteries to generate motion. These kinds of submarine tend to be complex to control and service and require specialized training to operate.
Generally, submarines require a propulsion capacity of about 2.5–5 kW to maintain an underwater speed of 2-3 knots. The average person riding a bicycle struggles to generate a propulsion capacity greater than 0.2-0.4 kW over a one to three-hour time period. This means a pair of furiously pedaling tourists couldn't muster enough power to propel an underwater vehicle.
But MIT has overcome the mathematical impossibility through both its innovative design as well as something called the Coanda effect. With both these elements in play, an average person, with the help of pedals, can generate the necessary underwater speed of between two and three knots, for two to four hours, to propel the company's two-passenger UV.
So what is this miraculous Coanda effect the company has employed? It is a phenomenon where a jet flow attaches itself to a nearby surface and remains attached even when the surface curves away from the direction of the initial jet flow. Run a stream of water over the underside of a spoon and watch as the water follows the curve instead of dropping straight down – that’s the Coanda effect.
In the same way, MIT's design uses rotor-jet propellers to take advantage of the Coanda effect. The propellers direct an air jet through a flat slot, in a tangential direction, onto the surface of the vehicle, where it adheres and generates thrust. The disc shape of the UV also helps to create a vacuum on the hull of the vehicle to provide additional draught. According to the St Petersburg State Marine Engineering University (SPbGMTU), which has been carrying out tests on the UV's design, this enables two people, still producing power of less than 0.4–0.8 kW, to generate the required speed of 2-3 knots for between two and four hours.
Its breakthrough design has allowed MIT to simplify the vehicle’s construction and operation, which has also helped to keep the cost of production down. The vehicle is small enough to be transported on the back of a car trailer. It measures 11.5 feet (3.5m) long, 4 feet (1.2m) high and 6.5 feet (2m) wide and weighs between 1.5 and 2 tons out of the water.
In the water, the UV can reach speeds of 2–5 knots on the surface and speeds of 2–3 knots under the water at depths of up to 30m. For those who don't fancy pedaling, MIT will also offer an optional low-power, combined electric drive.
The developers have also made sure the UV is simple to operate, with only foot pedals, steering wheel and minimal buttons and indicators to worry about. The onboard systems are also designed to function both in manual and automatic modes. Safety features include an automatic and mechanical drive for the release of ballast for surfacing in an emergency.
The vehicle also boasts a high degree of maneuverability: it can go forwards, backwards, up and down, hover and rotate about its vertical axis. Passengers will also be treated to spectacular underwater views with almost all of the UV's body transparent.
MIT is banking on the UV's relatively cheap price tag of between USD$30,000-$70,000, as well as its cheaper cost to operate and service, to find a market. Existing small submarines can range in price, from USD$100,000 to USD$200,000, and cost more to service due to their more complex mechanics. They also tend to require specialist training to operate.
It is not only the tourist market MIT is hoping to break into. It anticipates the UV will attract interest for uses in scientific research, underwater filming, technical survey of underwater structures, such as dams and pipelines, and underwater rescue.
Preliminary market research, carried out by MIT, suggests worldwide sales of the vehicle may go beyond 1 million units. MIT is seeking investors to fund the building of a prototype UV before establishing manufacturing facilities. Once in production, MIT expects to produce 10,000 vehicles a year.
Darren Quick
