Since you state that one of your father’s ships was sunk during the war, and clearly WAIMEA was not that ship, it must be that the ship you identify as SERGEANT MAJOR was the one that sank. However, I can find no evidence of a ship by that name, including among those known to have been sunk or damaged during World War II (see http://www.usmm.org/sunkaz.html#anchor29645).
There were two ships with distantly similar names that were both sunk in 1942: MAJOR GENERAL HENRY GIBBINS and MAJOR WHEELER but no ship named SERGEANT MAJOR.
If you want to pursue the name of this second ship, I suggest that you obtain your father’s complete service record, which should include the names of the ships in which he served and applicable dates. See this page within the Armed Guard website that I manage, http://armed-guard.com/searchmil.html. It is not clear from your message whether your father was in the U.S. Navy Armed Guard or whether he was in the U.S. merchant marine. Depending on that, the page offers two different paths to obtaining his service record.
If he was in the Armed Guard, see in particular on the above page section II.A.1 - Records of Individuals, Military, for instructions on requesting a copy of his records. You will have to contact the National Personnel Records Center in St. Louis, MO, and provide as much identifying information as you have (name, date and place of birth, date and place of death, Social Security Number, military ID number ["serial number"], etc.). The page has links to all of the information you will need to request his records, including a required form. There will be a fee for researching, photocopying and mailing the records but the Records Center staff will alert you to the cost before beginning work.
If your father was in the merchant marine, see on the same page section II.A.2. Records of Individuals – Merchant Marine. In this case you will have to contact the U.S. Coast Guard’s National Maritime Center in Martinsburg, West Virginia. The Coast Guard was and is responsible for issuing certain documents ("seaman's papers") and officers’ licenses to U.S. merchant mariners, so they should have information about your father if he was a merchant mariner. Again you will need to provide as much identifying information as possible about your father. And likewise there will be a fee involved.
Ron Carlson, Webmaster
Armed Guard / Merchant Marine website