The civilian merchant marine crew of CHRISTOPHER GADSDEN included a man named William Breece, age 17. (He had the rating of ordinary seaman, part of the deck crew.) I am sure this was the Carl Breece with whom you corresponded. A search of the Social Security Death Index confirms that a William Carl Breece died on the date you note. See http://search.ancestry.com/search/db.aspx?dbid=3693 to make the same search.
The merchant marine crew, whose names I did not list, included several men age 20 or younger, including two who were just 16. (There were also men in their 30s and 40s; the oldest was 50.) It is possible that some of those younger men are still living but again I would have no contact information. By necessity the merchant crew and the Armed Guard crew often worked very closely and no doubt friendships developed during voyages. Typically the merchant crew would have nearly a 100% turnover at the end of a voyage whereas the Armed Guard crew might remain intact or nearly so for several consecutive voyages, so Armed Guard and merchant sailors often quickly lost contact.