Future Market Application for Semi-submersible Barge Carriers

Many years ago, a semi-submersible barge carrying vessel carried small freight vessels between some Indian west coast ports and Gulf ports. Ongoing development in international trade may be developing new market applications for such technology. 

During an earlier era and prior to modern port development, many of India’s west coast ports were only capable of berthing very small vessels that at one time had carried international trade. As ship size increased to carry greater volume and/or greater tonnage, sailing draft increased to a depth had limited the number of ports at which such vessels could call. The combination of restricted sailing depth along navigable inland waterways and the need to increase freight carrying capacity resulted in the development of coupled vessel technologies and large vessels that were best suited to sailing in protected waters with very small waves. There are regions around the world where the mouths of different navigable inland waterways are relatively close and separated by short distances of energetic ocean. As a result, freight is transferred between inland vessels and ocean vessels at ports located within close proximity. In such environments, barge carrying semi-submersibles may have application.

Calm Water Zones

While the greatest distances of calm water zones involves navigable inland waterways, there are several ocean regions where water is mostly calm. One such region occurs in Western Japan, between the Provinces of Shikoku, Kyushu and Honshu. Other such regions occur at Long Island Sound and at Chesapeake Bay on the American east coast while islands on the west side of the Philippines provide narrow navigable ocean channels. Like inland waterways, there are several large cities located around the calm water zones and with the option of having small freight vessels being able to sail to the dock areas.

Barges on Semi-Submersibles

Western Japan – Western Philippines
 
Depending on future volumes of trade, semi-submersible vessels could carry barges between the calm water zones located at Western Japan and Western Philippines. The trade would directly connect large Japanese cities like Kobe, Osaka, Hiroshima and Kitakyushu to Philippines cities such as Manila and cities such as Tacloban, Cebu – Mandaue, Bacolod and Iloilo. One operational option could involve a semi-submersible carrying barges loaded with of Philippines trade from Manila to Western Japan. 

Philippines – China Trade

The close proximity between Manila and Hong Kong enhances the option of carrying barges laden with trade aboard semi-submersibles. Upon arrival at Hong Kong, barges would sail across to Macau and toward inland destinations located along the Xijiang River, also to destinations located on navigable waterways that connect to Hong Kong. Semi-submersibles may also carry barges between Philippines and Shanghai, from where barges would sail to and from destinations located along the Yangtze River.  
Other Asian trade that connects Philippines or China to Thailand and Cambodia could involve semi-submersibles carrying barges to the mouths of the Mekong River and the Chao Phraya River at Bangkok.

Indian Trade

Major sections of the Ganges River are navigable and carry trade that connects main northeastern Indian cities to each other and to the rest of the world. On the eastern side of the Bay of Bengal, the Irrawaddy River is navigable and able to carry trade inland toward cities such as Mandalay. India’s Ministry of Transportation is expected to expand future navigation along the Ganges.

Pakistan

China has been assisting Pakistan in developing a section of the Great Silk Road that includes roads, railway lines and ports. The Indus River has long been navigable and there is scope to further develop and expand future inland waterway navigation along that river. Semi-submersible vessels could carry barges that sail the Indus River, to ports located around The Gulf.

North African – European Trade

The Nile River is navigable from the Mediterranean Sea inland to both Cairo and Khartoum. Barges that sail along the Nile River could also sail along the Danube River as well as navigable Russian inland waterways. Semi-submersibles would carry barges between Alexandria on the Mediterranean Sea and mouths of navigable Rivers located around the Black Sea. 

Equatorial African Trade

Barges and river boats carry trade along navigable inland waterways such as the Niger and Benue Rivers of Nigeria as well as major sections of the Congo River. There would be scope for semi-submersible vessels to carry barges between the mouths of the Niger and Congo Rivers. The main advantage for African economies is that waterway transportation involves much lower operating cost per ton of cargo that either of truck or railway transportation.

South American Trade

Coupled tows of river barges carry trade along the Parana River between Buenos Aires and Asuncion and also along the Uruguay River. At northeastern Brazil, the Sao Francisco and Amazon Rivers are both navigable while the narrow-gauge intercity railway system does move freight. The combination of coastal ships and sailing along inland waterways offers competitive transportation rates to both railway and long-distance truck transportation. Semi-submersibles that connect to large ports such as Santos near Sao Paulo or to Rio de Janeiro could take aboard or discharge barges near the Port of Buenos Aires.

Containers-On-Barges (COB)

Container-on-barge transportation is developing along the European inland waterway network, along South American waterways and even along the American inland waterway system. Before barges carrying containers are taken aboard semi-submersibles, there would likely be need to transfer containers amongst the barges so that all containers aboard each barge share the same destination port. Semi-submersibles designed to carry a single level of barges may optimally sail short distances across ocean such as between the mouths of the Mekong and Chao Phraya Rivers, between the Ganges and Irrawaddy Rivers or across the Black Sea between the Danube and a navigable Russian river.

Multi-level Semi-submersible

Semi-submersible vessels capable of carrying multiple levels of container laden river barges are a future possibility on some routes. The large vessel would require the equivalent of built-in hydraulic jack mechanisms that would extend to the seafloor while at a terminal where it either discharges or takes aboard container barges. Prior to departure, laden container barges would be pushed onboard on to the top level while the semi-submersible is at its maximum design depth, the jack mechanisms maintaining roll stability. Once the uppermost level is fully laden, the semi-submersible would rise to next elevation and stabilized by jacks.

The semi-submersible would be loaded in sequence from top level to bottom level, when it would then rise to sailing draft and rear stern doors shut. An external floating power generator to be towed by the semi-submersible would provide propulsive energy to electrically powered propellers (azipods). Upon arrival at the destination discharge point, the hydraulic jacks would lower to the sea floor. Laden barges would then be floated off each level of the semi-submersible in sequence, beginning at the lowest level and progressively offloading each higher level until all barges have been offloaded.

External Ballast Tanks

The use of a vessel of port-based ballast tanks could assist in loading and unloading multi-level, barge-carrying semi-submersible vessels. Upon arrival, the port-based ballast tank vessel would be secured to the hull of the semi-submersible. Its design could also include stabilizing jacks that extend to the sea floor, with the additional ballast tanks assisting to lower and raise the semi-submersible as laden barges are either floated off or taken aboard via the stern. The use of external ballast tanks could allow for a design of semi-submersible capable of carrying up to 2-levels of laden barges below the water line.

Stern Doors

The use of stern doors on the semi-submersible would allow for construction of a bow capable of withstanding severe wave conditions while eliminating the risk of severe sailing conditions opening bow doors. Stern doors would require the use of either a forward mounted engine located near the bow or the engine installed inside a remote power generation unit that would attach to the sides of the semi-submersible’s stern. The power generating unit would include its own propeller to minimize tension in towing cables. A possible market application may be to link Port of Singapore with cities along India’s Ganges River.

Conclusions

The future nature of international trade will determine future market application for semi-submersible vessels capable of carrying multiple levels of fully laden river barges.