Some ports and areas depend for access upon canals and waterways. The problem with waterways is always one of size and one has seen in such places as the Thames, where the increase in ship sizes has caused docks nearer to the city slowly to fall into disuse and those further down stream to be developed. The problem of size is even more apparent when one is looking at man-made waterways that have been specifically built to create or improve access. What may have seemed more than big enough at the time of construction can be very restricting to contemporary sizes of ships. A good example of this is the St Lawrence Seaway that is in fact a series of canals linking the North American Great Lakes to the sea. The Lakes themselves have plenty of depth but the decision had to be made on the dimensions of the canal locks. These were an enormous undertaking; one must remind oneself of the Niagara Falls because that is the height that the locks have to lift ships from Lake Ontario to Lake Erie. Eventually the compromise between ships’ requirements and civil engineering constraints resulted in limitations of 26 feet fresh water maximum draft with 222.5 meters maximum length and 23.16 meters maximum beam. In practice this has meant that the largest ships the Seaway can accept are of about 30,000 DWT which can load up to about 18,000 mtons on the Seaway draft of 26′ and then complete (‘top-off’) at Montreal. Because of the complexity of the different canals and locks, ships have to equip themselves with several extra accessories such as special fairleads for their mooring lines, on-board sewage systems to avoid polluting the lakes, extra lighting etc. Managers of ships intending to enter the Lakes are advised to make their preparations well in advance. Despite these restrictions, to which must, of course be added the complete shut-down during three of the winter months due to ice, the St. Lawrence Seaway is still a very valuable link to the grain and industrial heartlands of the USA and Canada. The Panama Canal which first opened in 1914, links the Atlantic and the Pacific oceans thus saving many days of steaming round the southern tip of South America. So important is this link, especially to Japan, that a study into building a second, larger canal has been initiated by that country.
New Panama Canal locks 2015 restrictions: The new locks at Panama Canal are designed for passage of vessels with draft up to 50 ft (15.20 m), and length of 366 m. “New Panamax” to describe a design incorporating the maximum dimensions that the canal can accept, is now firmly implanted in shipping’s vocabulary.
Just as famous and even older is the Suez Canal which fortunately for the builders in 1859 needed no locks as the levels of the Mediterranean and the Red Seas are the same; even so it took ten years to build. Because there are no locks, it has been possible to increase the dimensions of the Suez Canal as ships have increased in size. This now means that ships drawing as much as 53 feet can be accepted which allows ships of around 150,000 DWT fully laden to use it and ships in ballast as large as 370,000 DWT can be accommodated.