by Guest » October 5, 2023, 1:55 pm
Investigation into the load lines on the Great Lakes came about in the early 1960s when it was realized that the existing load line regulations didn't adequately cover the longer vessels coming into service and the planned 800 to 1,000 foot lakers.
A committee was formed by the Society of Naval Architects and Marine Engineers and included the American Burea of Shipping (ABS), the US Coast Guard, and the Department of Transport in Canada.
Several vessels were instrumented with hull stress gauges, and the Edward L. Ryerson even had wave buoys that were deployed from her deck to measure wave heights, lengths and other wave spectra data. It was discovered during the Daniel J. Morrell storm in late November 1966, when the Ryerson was on Lake Michigan, that wave lengths could reach over 700 feet in length and not the previously assumed 250-350 feet in length.
The ships that were built in the 1950s didn't receive strapping when they were granted increased load lines, but they did require stronger doors on the spar decks, increased heights of the ballast and tunnel vents and various other modifications. The Supers and Maritimers received deck strapping to increase their hull section modulus along with the other changes noted for the 1950s built ships.
After the Fitzgerald sank, the NTSB and Marine Safety Board recommended that the load line changes be rescinded, but this never came about. Instead existing load lines stayed in place as vessel owners increased the strength of ships from the 1950s by doing conversions to self-unloaders - in those so done. An excellent write-up on the load line changes and hull springing of the Great Lakes ships was presented by David Groh at the Ship Structures Symposium in early Fall 1975.
http://www.shipstructure.org/pdf/75symp09.pdfInvestigation into the load lines on the Great Lakes came about in the early 1960s when it was realized that the existing load line regulations didn't adequately cover the longer vessels coming into service and the planned 800 to 1,000 foot lakers.
A committee was formed by the Society of Naval Architects and Marine Engineers and included the American Burea of Shipping (ABS), the US Coast Guard, and the Department of Transport in Canada.
Several vessels were instrumented with hull stress gauges, and the Edward L. Ryerson even had wave buoys that were deployed from her deck to measure wave heights, lengths and other wave spectra data. It was discovered during the Daniel J. Morrell storm in late November 1966, when the Ryerson was on Lake Michigan, that wave lengths could reach over 700 feet in length and not the previously assumed 250-350 feet in length.
The ships that were built in the 1950s didn't receive strapping when they were granted increased load lines, but they did require stronger doors on the spar decks, increased heights of the ballast and tunnel vents and various other modifications. The Supers and Maritimers received deck strapping to increase their hull section modulus along with the other changes noted for the 1950s built ships.
After the Fitzgerald sank, the NTSB and Marine Safety Board recommended that the load line changes be rescinded, but this never came about. Instead existing load lines stayed in place as vessel owners increased the strength of ships from the 1950s by doing conversions to self-unloaders - in those so done. An excellent write-up on the load line changes and hull springing of the Great Lakes ships was presented by David Groh at the Ship Structures Symposium in early Fall 1975. http://www.shipstructure.org/pdf/75symp09.pdf