As researchers and historians speculate what kind of vessels are in the sonar image noted by BrooklynPaper.com (today and this past February), we’d like to direct everyone to an image that the Brooklyn Historical Society has of vessels submerged in the Gowanus Canal. According to their records this image was taken in 1960 from 3rd Street.
Please click on the link to see more detail. Brooklyn Historical Society
*it also should be noted that in 1954 there was a large fire near the Canal, during which buildings and boats were damaged. It is possible that the ship featuring in the sonar image is from this fire. See Brooklyn Public Library archives (image from Brooklyn Eagle paper 1954)