Whatsit on Cartoon Channel??? Flapjack, who is around this age and hangs out with an old salt ("Captain"), a ne'er-do-well, of course, who fills him full of ideas about adventures, and both of them live inside a whale named Bubbie?
Good of you to start the little sailor early before the good influences catch up with him. Yaaarrrg! Arrr! Arrr! "Fifteen men on a dead man's chest!"