Coastwise

The modern terms short sea shipping, marine highway and motorways of the sea refer to the historical terms coastal trade, coastal shipping, coasting trade and coastwise trade, which encompass the movement of cargo and passengers mainly by sea along a coast, without crossing an ocean. 'Deep-sea shipping', 'intercontinental shipping' or 'ocean shipping' refers to maritime traffic that crosses oceans. While 'short-sea shipping' is the term used in Europe, the United States also has used the term, 'marine highway'.

Historically, many developed English-speaking countries used the British term 'coasting trade' or 'coastwise trade', which is still used. The coastwise slave trade referred to the domestic slave trade in the United States that shipped slaves by water from the Upper South to major markets, especially New Orleans.

The United States maintained this term from its colonial era and began regulating the coastwise trade as early as 1793, with the Congressional passage of "An act for enrolling and licensing ships and vessels to be employed in the coasting trade and fisheries, and for regulating the same", which passed on 18 February that year. Over the years, it has been codified as 46 U.S.C., Coastwise Trade.

Some short sea ship vessels are small enough to travel inland on inland waterways. Short sea shipping includes the movements of wet and dry bulk cargoes, containers and passengers around the coast (say from Lisbon to Rotterdam or from New Orleans to Philadelphia). Typical ship sizes range from 1,000 DWT (tonnes deadweight – i.e. the amount of cargo they carry) to 15,000 DWT with drafts ranging from around 3 to 6 m (10 to 20 ft). Typical cargoes include grain, fertilisers, steel, coal, salt, stone, scrap and minerals (all in bulk), oil products (such as diesel oil, kerosene, aviation spirit – all in bulk), containers and passengers. Short sea shipping should not be mistaken with inland navigation.

In Europe, short sea shipping is at the forefront of the European Union's transportation policy. It currently accounts for roughly 40% of all freight moved in Europe. In the US, short sea shipping has yet to be used to the extent it is in Europe, but there is some development. The main advantages promoted for this type of shipping are alleviation of congestion, decrease of air pollution, and overall cost savings to the shipper and a government. Shipping goods by ship (one 4,000 DWT vessel is equivalent to between 100–200 trucks) is far more efficient and cost-effective than road transport (though the goods, if bound inland, have to be transferred and delivered by truck) and is much less prone to theft and damage.

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