Masterman Ready by Frederick Marryat

The genteel Mr. Seagrave, the frequently indisposed Mrs. Seagrave and their four children: William, twelve, Tommy, six, Caroline 7 and Albert who is not yet one, sail on board the Pacific en route to the Seagrave's home in Australia. The Pacific runs into several storms and when the captain is struck unconscious, the ship's crew abandon the ship wholesale with the exception of the selfless Masterman Ready who elects to remain onboard the doomed vessel to help the Seagraves and their negro maid, Juno. Eventually, the weather clears and the prescient Ready leads the Seagraves to relative safety on a desert island where they seek food and shelter, survive several adventures and are even attacked by natives.