- By Lisa Busch

 

 

Since the first fishing vessel plied the sea, humans have dreamed of new ways to tap into the world's ocean resources. Using ocean waves to generate power, feeding the hungry with seaweed, and desalinating seawater are some of the grander schemes. Recently, a few new ideas have landed on the horizon that have engineers thinking really big. A floating military base, an at-sea container-ship transfer station, and a floating city may be the next generation of ocean frontiers.

A navy-designed military base called a Mobile Offshore Base (MOB) would be the largest floating structure ever constructed. The idea behind the MOB is that a one mile by 300 meter floating base could be deployed in international waters anywhere in the world. Though the estimated $10 billion dollar price tag on the MOB is daunting, its creation could theoretically mean a long-term savings by providing an as-needed military base rather than operating one for years that is only utilized every few decades. The MOB would be a semi-submersible structure that has a million square feet of storage, holds 10 million gallons of fuel, and houses 3,000 troops.

The MOB would be constructed by connecting five or six semi-submersible modules, each two or three times the size of a standard oil drilling platform. Ronald Riggs, a professor of civil engineering at the University of Hawaii at Manoa, worked on the MOB project. He believes that while the large size is new, the technology is not. “It's evolutionary, not revolutionary,'' says Riggs. Still, the giant floating structure requires some major innovations from the engineering community.

The Office of Naval Research contracted with different firms to come up with the best system to connect the floating modules. One connection idea is a railroad hitch design. Another company designed the modules to be positioned quarter-miles apart connected by an accordion-type bridge running through a hollow truss. A third company designed the units to be 50 feet apart. In this design, the modules wouldn't even be physically connected, but would be kept in close proximity by a computer system that was constantly repositioning the modules to stay grouped. If the wind or waves changes direction, for example, so would the modules. One of the difficult aspects of the MOB is determining the effects of waves on a structure this size. Because there is no wave tank in existence to study how a mile-long object could be impacted, MOB researchers did some basic wave research with the National Atmospheric and Space Administration. NASA flew a plane into a hurricane to snap pictures of extreme waves—at least one of which was over a mile long.

The Department of Defense spent $36 million and five years developing MOB. “The take-home message is that the engineering is there and this is not a crazy idea,'' says Paul Palo, the technical manager for the MOB effort. But just because something is technically feasible does not guarantee its political acceptance. After the Washington-based think tank the Institute for Defense concluded there is no reason to build the MOB, Congress deep-sixed the research program, at least for the time being. Meanwhile, the private sector is trying to apply MOB research to the world of ocean transportation through an idea dubbed Seahub. The concept is that one modified module of the MOB could be designed to be a floating cargo-ship transfer station.

Shipping companies are planning to improve efficiency by building larger and larger vessels that can haul more containers. Currently, most ships carry about 1,500 containers, but the new superships are expected to carry over 15,000 containers. While moving more quantity faster is theoretically more efficient, the superships will be too large to dock in many U.S. ports. Rather than dredging harbors, which can be costly and have deleterious impacts on the marine environment, Seahub could create a port at sea where large vessels would transfer their loads to smaller vessels that shuttle the containers to port. The Seahub project is being developed by the Coastal Operations Institute, a Florida-based consortium that includes federal and state agencies as well as private companies and universities.

Shipping News

Elan Moritz, head of Littoral and Expeditionary Warfare Technologies at the U.S. Navy Coastal System station in Panama City, Fla., conceived the idea. He sees the Seahub proposal as a timely response to the shipping demands of the North American Free Trade Agreement, which claims that north-south trade demands will quadruple in the next 20 years. However, demands may not be met because of the primitive transportation conditions of the rail lines and trucking highways in Mexico. “Seahub could be a way of placing a sophisticated delivery point in places that don't have developed shipping systems,'' he said.

Moritz doesn't believe Seahub will pose many challenges for design theory because the station would essentially be just two or three times the size of an oil drilling rig. However, Moritz says it creates a whole set of interesting new hurdles for systems engineers. “There are opportunities to build in new technologies for inspecting containers to prevent smuggling contraband,'' he says. “In a Seahub situation, one could design automated inspection systems that could save truckers time down the line, which translates into an economic savings.'' He suggests developing Global Positioning System units to track individual containers from departure to arrival. Seahub will require new cranes that can handle unloading in high seas conditions.

A new generation of fast shuttle ships will be needed to take the containers efficiently to shore. Also, engineers could develop new scheduling systems to move large volumes of goods more quickly and easily. “We are making people aware of the issues and trying to encourage academics to think about this,'' says Moritz. He believes the Department of Transportation and private shipping organizations would also have an interest in developing the idea.

 

OceanFront Property

A company in Florida aims to exploit the vastness of the ocean to create a new lifestyle—a floating city. The Freedom Ship is a proposal to build a 4,320 foot long vessel, 25 stories high, that accommodates 115,000 people. The idea of the ship is to build a floating city with schools, hospitals, and all the amenities of urban life. If built, it will be the largest floating ship in the world, yet proponents and sponsors don't expect any amazing technological advances in ship design will be employed to pull it off. “It might not be architecturally beautiful, but it will be structurally sound,'' says Norm Nixon, CEO of the Freedom Ship International.

The Freedom Ship was designed by structural engineers rather than naval architects because, Nixon says, naval architects are often too focused on efficiency and speed, which was of little concern to his group. “We gave up speed for economics,'' he said. The boat is designed with a barge-like square hull and constructed from heavy steel that will be bolted rather than welded together.”The bolt heads will stick out and there will be more resistance in the water, but we don't need to go fast,” says Nixon. The Freedom Ship will travel at 10 knots and circumnavigate the globe every two years.

While the so-called primitive design may be more economical, the price tag is still a hefty $10 billion. The proponents of the idea are spending most of their time these days selling shares in the boat. A 450-square-foot apartment goes for around $150,000, while a 5,000- square-foot unit sells for $8 million. With the structural design of the vessel complete, engineers are working on internal systems such as waste, transportation, and communication systems. Engineers say they plan to use state-of-the-art incineration toilets to dispose of human waste, and there will be an on-board train for on-board travel.

One of the big engineering hurdles was finding a way and a place to construct the giant ship. Dry dock construction for a ship this size is not practical, so the company secured land in Honduras to construct a staging area where the base of the ship can be built in smaller sections. The sections will then be put in the water in 300 x 400 foot lengths and, like high-rise construction, the base will be used as the construction base for the rest of the boat. Former Texas A&M mechanical engineer professor Swicki Anderson has worked on the thermal engineering aspect of the ship. “It is feasible,” says Anderson. “As we see more and more productive land mass converted to urban sprawl, there is a greater incentive to examine this (Freedom Ship) as a human habitat.'' Anderson has worked on the thermal mechanical aspects of the ship for the past three years. “It takes a lot of thinking and head scratching to get the first one done, but it gets easier after that.''

 

Lisa Busch is a freelance writer based in Sitka, Alaska. She can be reached at lbusch@asee.org.