This novel, which many consider the best of Arthur Ransome's many tales of adventure for youngsters, finds our heroes quite literally out to sea -- adrift in a gale, alone, in the North Sea. The seventh installment in Ransome's Swallows and Amazons, featuring the most about boats and the most thrills. Not to fear, the kids are amazing and everything turns out in the end.  (GBR483, $14.95)