in Lake St. Clair) restricts the cargo capacity of lakers, but that is partially recovered by their extra length and box design. Since Great Lakes waves do not achieve the great length or period of ocean waves, particularly compared to the waves' height, ships are in less danger of being suspended between two waves and breaking, so the ratio between the ship's length, beam and its depth can be larger than that of an ocean-going ship. The lake vessels generally have a 10:1 length to beam ratio, whereas ocean vessels are typically 7:1. The dimensions of the locks is the determining factor in lake vessel construction. Lifespan Since the fresh water lakes are less corrosive to ships than the salt water of the oceans, many of the lakers remain in service for long periods, and the fleet has a much higher average age than the ocean-going fleet. The average lifespan of a laker is 40–50 years. Until 2014, , built in 1906 as William P. Snyder (), was the oldest ship in active duty on the lakes. She was managed by Port City Steamship and owned by St. Mary's Cement, a subsidiary of Votorantim Cimentos. E. M. Ford had one of the longest careers, having been built in 1898 (as Presque Isle – ) and still sailing the lakes 98 years later in 1996. In 2007, she was still afloat as a stationary transfer vessel at a riverside cement silo in Saginaw. She went to the scrap yard in November 2010 at Purvis Marine in Sault Ste. Marie, Ontario. , built in 1904, last sailed in 1985 and in 2007 served in the same capacity as E. M. Ford at a cement silo in Superior, Wisconsin. Several decorated World War II veteran ships are still in active, although civilian, use such as the tankers Chiwawa and Neshanic (scrapped 2018), now the bulk freighters Lee A. Tregurtha and American Victory, respectively, and the Landing Craft Tank 203, now the working vessel Outer Island. Newest freighters Some shipping companies are building new freighters to ply the waters of the Great Lakes. The following are new freighters in use or will be launched for use in the Great Lakes: – built by Chengxi Shipyard of Jiangyin, China, delivered in August 2011 for Algoma Central Corporation. – a new class of lake freighter, several of which entered service in the 2010s for Seaway Marine