Ship Economics: Multi-Port Shipping Using Trans Oceanic Ship/Barge Trains
Op Ed by Harry Valentine
The history of commercial sailing includes the history of ongoing innovation aimed at reducing transportation costs. Ships have become progressively more cost competitive even prior to the days of the Roman Empire. Ongoing technical innovation from river transport such as coupled sailing units, it beginning to appear on the ocean with the development of the ‘unrestricted’ hull for coupled barges that have oceanic sailing capability.
Canada’s Northern Transportation Company has sailed tug-pushed barge-tows of up to 15-coupled units along Canada’s Mackenzie River and ocean capable tug-pushed barges into the Beaufort Sea and Hudson Bay. Further development of oceanic barge trains with ‘unrestricted’ hulls would likely see the technology sailing across oceans within the next few decades. There appears to be a market application awaiting a maritime technology that is currently under development.
The ports of New York City and Boston are within close proximity to each other, as are the ports of Rotterdam and Edinburgh. Oceanic barges originating from Edinburgh and Rotterdam may be coupled into a barge-tow in the North Sea and sailed across the North Atlantic to the Northeastern USA. One barge will be uncoupled at the Port of Boston while the other barge would continue on to the Port of New York.
There is a long list of major international ports that are located within close proximity to each other. The list includes:
- San Diego (Long Beach), Los Angeles and San Francisco
- Seattle (USA) and Vancouver (Canada)
- Sao Paulo and Rio de Janeiro
- Buenos Aires and Montevideo
- Boston, New York and Newark
- Philadelphia, Baltimore and Norfolk (Newport News)
- Stockholm, Helsinki and Leningrad
- Rotterdam, Hamburg, Edinburgh and London
- Liverpool and Dublin
- Barcelona, Marseilles and Rome
- Tokyo, Yokohama, Nagoya and Osaka
- Jeddah and Port Sudan
- Calcutta and Dhaka
- Karachi and Bombay (Mumbai)
- Colombo and Madras (Chennai)
- Shanghai, Pusan and Seoul
- Canton, Hong Kong and Taipei
- Singapore, Jakarta and Kuala Lumpur
- Sydney and Melbourne
- Istanbul, Athens and Odessa
- Alexandria and Beirut
- Abu Dhabi, Dubai, Doha, Manama and Kuwait City
- Cape Town, Port Elizabeth and Durban
In terms of the distances that relate to trans-oceanic intercontinental maritime transportation, the nearby ports in the above list are relatively close to each other. The trans-oceanic voyage may account for 80% to 90% of the voyage, while the distance between the nearby ports may account for less than 10% of the distance. There is an economic advantage involved in sailing a coupled ship-train for 80% to 90% of the voyage, then sailing single unit ships for some 10% of the remaining voyage.
Engineers and maritime architects at the Freedom Ship Group of Florida designed an ocean going barge of over 4000-ft length. Their research may serve as a partial basis for further research into extended length, coupled-ship technology. To save fuel, the stern of the leading oceanic coupled-barge would be designed to overlap the bow of the trailing barge, so that the trailing barge would sail in the hydraulic shadow of the barge ahead of it.
While locking the coupling between barges may be impractical on the ocean, given prevailing ocean conditions, there may be the option of using computer controlled side thrusters to achieve directional control. Autonav developed a computer control system that may maintain directional control of unlocked articulation couplings of barge trains. Their technology has successfully been applied to coupled-barge-trains that have sailed on the Mackenzie River. That precedent provides a basis upon which to develop that technology for trans-oceanic applications.
Oceanic ship trains would need to ‘borrow’ some of the multiple-unit control technology from the railways. All sailing units on the oceanic train would connect to a common power cable and a multiple-unit control cable. Each unit would have bilge pumps and a bow side thruster. The bridge for navigation may be near the bow of the lead unit, with the multiple-unit control cable carrying navigation signals to various units along the oceanic train.
A large oceanic push-tug with some 25,000kW or more of engine power may provide propulsion from the stern of the oceanic train. It will carry a small crew and receive navigation signals from the forward bridge, similar to a railway commuter train where the driver is located in the cab of the leading passenger coach while the diesel locomotive pushes from the rear. An alternative approach involves a locomotive with electric motors and a power generation source at a remote location.
A maritime vessel equipped with an electrically driven propeller may also receive electric power from an outside source, including via an insulated power cable that connects to another vessel. The barge couple to the rear of the barge-tow may be built with electrically driven propellers housed in azipods. Power generation would occur on a towed twin-hull catamaran unit, with towing cables and a power cable connecting to the coupled barge-assembly. Most of the water stream from the propellers would flow between the twin hulls of the power-generating unit.
There may be scope to modify an existing ship to push a non-powered companion vessel of equivalent hydraulic cross-sectional area, across the ocean. Its bow would require modification, as would its propulsion system. During the oceanic voyage, the extended length coupled train would require 10% to 15% more propulsive power than a single sailing unit of equivalent hydraulic cross section at the bow. Ocean capable tugs may push on the stern of the train assembly as it leaves port, accelerating it over a distance of several nautical miles until it reaches its cruising speed.
Barge-tows that sail via the Panama Canal may have to be uncoupled to transit the waterway. A locally owned tug may push the non-powered barge section through the canal locks. Despite the cost of hiring the tug, an extended length oceanic train sailing between Eastern Asia and Western Europe could still be cost-competitive on extended length voyages.
There is ongoing research in the area of sailing barges built with ‘unrestricted’ hulls, on to the ocean. Such technology already sails into the Beaufort Sea, Hudson Bay and more recently into the Gulf of Mexico, where such technology will be sailing between the Port of New Orleans and nearby Caribbean ports. Further research would develop the technology for trans-oceanic voyages.
As ocean train technology develops, a future market application awaits an ocean train technology that can sail multiple units across the ocean, between nearby ports located at the origin and destination of such voyages. The same size of crew could more tonnage and more containers across the ocean while burning less fuel per ton of cargo or per container. Oceanic trains that sail across the ocean and serve multiple nearby ports at the origin and destination, promise to evolve into a cost-competitive maritime transportation technology.
Harry Valentine can be contacted at firstname.lastname@example.org for comments and/or questions.