No, A tube over a ratchet will strip and kill your ratchet...the forces required to both undo the crank bolt and then do it up again ,will kill it! A decent breaker bar is worth its weight in gold...esp. for the head bolts too...Looks like I need a breaker! Having said that, you must mean a long, strong, tubular bar that will fit over a socket wrench.
Your thinking of a cheater bar!