Coot Club by Arthur Ransome
Tom Dudgeon has cast off a motor cruiser from its moorings to protect a coot's nest, but now the cruiser is searching high and low for him - even offering a reward. Tom accepts an invitation for a week's cruise to teach his new friends, Dick and Dorothea how to sail. You couldn't get a better sailor than Tom but can he really stay one jump ahead of his pursuers long enough to complete the voyage?