John Cunningham 
The Apes of Devil’s Island [EPUB ebook] 

When Jimmy Wendell takes a yachting trip with some friends, he never expected to become involved in an attempted murder of the crew and the ship’s destruction on a reef. Making it to a small, shark-encircled island, Wendell will soon learn of the ape inhabitants of that mysterious land….
Argosy often revisited the themes from their most popular stories, and this is no different: author John Cunningham pens a tale of high adventure that has been forgotten for too long.