Forensics 2012

The Civil War era Ironclad USS Monitor, foundered in heavy seas off Cape Hatteras, North Carolina, December 31st 1862. The paper focuses on the development and validation of numerical models of a ship foundering using the USS Monitor as a test subject. It begins with a brief account of vessel’s history and the circumstances leading up to the sinking. We then present the best estimate available for the vessel’s loading condition and hydrostatics. The ingress of water into the wreck at a number of locations is in the historical record. There was speculation by the survivors that the hull began to separate forward due to slamming in waves, but the degraded condition of the wreckage after 149 years on bottom does not easily lend itself to verify or refute this point. 

Several linear and non-linear seakeeping models were run on this hull form, steaming, under tow and after the anchor was dropped just prior to the final sinking. The seakeeping models provide time histories of hydrostatic head at each of the down flooding locations.

The seakeeping models provide estimates of the slamming of the overhanging bow in moderate to large waves as reported in survivor testimony. The numerical tools developed to support this analysis will be able to support the analysis of other vessel foundering events.

The breakup and sinking of the Edmund Fitzgerald in November of 1975,with the loss of 29 souls, has garnered wide and enduring public interest. It has been the topic of a popular song as well as a number of television documentaries that have espoused a range of scenarios ranging from the plausible to the highly unlikely. The focus of this paper is to develop numerical modeling methodology to investigate the breakup of a ship in heavy seas. The Edmund Fitzgerald provides an example that is useful in developing these tools that can then be generalized to investigate other vessels. This paper will begin with a summary of the history of the vessel and the factual events leading up to her sinking. Next a detailed weights accounting and hydrostatic analysis that establishes the condition of the ship will be presented. The wreck lies on the bottom in two major pieces and as a confused debris field representing the middle 200 feet of the ship. An analysis of the strength of the hull girder in the locations corresponding to the established damage is presented. Several different linear and non-linear seakeeping programs have been used to study the vessels motions at various times over the voyage. These results include time histories of green water on deck as well as the primary loads on the hull girder due to wave induced stresses. Based upon these new and state of art analyses, a new plausible scenario will be presented that takes all of the known facts into account.