Ballantyne, R. M: The Coral Island. V1. 24 Sep 2010
 

R. M. Ballantyne (24 April 1825 – 8 February 1894) was a Scottish juvenile fiction writer.
Born Robert Michael Ballantyne in Edinburgh, he was part of a famous family of printers and publishers. At the age of 16 he went to Canada and was six years in the service of the Hudson's Bay Company. He returned to Scotland in 1847, and published his first book the following year, Hudson's Bay: or, Life in the Wilds of North America. For some time he was employed by Messrs Constable, the publishers, but in 1856 he gave up business for the profession of literature, and began the series of adventure stories for the young with which his name is popularly associated.

Excerpt
One night, soon after we entered the tropics, an awful storm burst upon our ship. The first squall of wind carried away two of our masts, and left only the foremast standing. There was no room for me upon the lifeboat; but being left behind saved my life -- and the lives of Peterkin and Jack Martin, my two companions. "Come, boys," said Jack Martin in a grave tone as we stood on the quarterdeck awaiting our fate -- "You see it is impossible that the little boat can reach the shore, crowded with men." He had us take hold of a loose oar, and guided us to shelter on a deserted coral isle. . . . . . . and that is the beginning of my harrowing tale.

Thank you! I read this when I was a boy; I have no idea where I came across it. It's going to be fun rediscovering the literature of a twelve-year-old.