what is the second hypothesis ?
The LCA believed that the more probable cause was shoaling or grounding in the Six Fathom Shoal northwest of Caribou Island when the vessel "unknowingly raked a reef" during the time the Whitefish Point light and radio beacon were not available as navigation aids.
SS Edmund Fitzgerald
The LCA believed that instead of hatch cover leakage, the more probable cause of "Edmund Fitzgerald"s loss was shoaling or grounding in the Six Fathom Shoal northwest of Caribou Island when the vessel "unknowingly raked a reef" during the time the Whitefish Point light and radio beacon were not available as navigation aids. 
when did the wreck of the edmund fitzgerald happen November 10, 1975 what is it ? It was an American Great Lakes freighter ship. when was it launched ? June 7, 1958 how did it get its name ? It is named after Edmund Fitzgerald - president and chairman of the board of Northwestern Mutual. when did it sink ? November 10, 1975 how did it sink ? Extreme weather and sea conditions play a role in all of the published hypotheses regarding its sinking. give some examples of such hypotheses ? Rogue wave hypothesis, Shoaling hypothesis, Structural failure hypothesis etc.
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SS Edmund Fitzgerald [SEP] Shoaling hypothesis
The LCA believed that instead of hatch cover leakage, the more probable cause of "Edmund Fitzgerald"s loss was shoaling or grounding in the Six Fathom Shoal northwest of Caribou Island when the vessel "unknowingly raked a reef" during the time the Whitefish Point light and radio beacon were not available as navigation aids. This hypothesis was supported by a 1976 Canadian hydrographic survey, which disclosed that an unknown shoal ran a mile further east of Six Fathom Shoal than shown on the Canadian charts. Officers from "Arthur M. Anderson" observed that "Edmund Fitzgerald" sailed through this exact area. Conjecture by proponents of the Six Fathom Shoal hypothesis concluded that "Edmund Fitzgerald"s downed fence rail reported by McSorley could occur only if the ship "hogged" during shoaling, with the bow and stern bent downward and the midsection raised by the shoal, pulling the railing tight until the cables dislodged or tore under the strain.