No such song I suspect. Confusion might arise because sites about famous sinkings tend to include both the Belgrano and the Edmund Fitzgerald, with a note about Gordon Lightfoot's song about the latter - and both tend to turn up together in abbreviated Google search headings - for example:

FAMOUS SHIPWRECKS WORLDWIDE
www.shipwreckexpo.com/famousshipwrecks.htm
Thanks to the popular 1976 song by singer/songwriter Gordon Lightfoot, the story of the ... The sinking of the warship Belgrano is one of the most dramatic and ...