Chris is correct about that. The boat is repairable, but to do it the right way, it's gonna cost you a bunch of money. The current owner did'nt want to dish out the big $$$, so he did it the cheap way, and it came back after about a few hours of running in some choppy waters. Until it's fixed properly, all you'll be doing is chasing the problem.
That's probably why he never puts the boat in the water, cause he does'nt want the crack to "reappear".