Crazy man looking to step on nortons

[willy]

Need advise from you guys. A little hole in the wall marina in Rockaway NY is selling a brokerage boat the guy just wants them to get rid of $1200 no trailer. Went to see it today, 1986 v20 with a reportedly non-working yamaha 115 same year on it. Motor looks great from outside but obviously does'nt tell you much. The transom is solid as a rock, pulled screws out of it and they were dry and had solid purchase when screwed back in, no water weeping at all below water line. Rocked engine back and forth, solid ;D Hull is solid all over. Boat needs cosmetic stuff done which I can do. The problem is that the starboard stringer along side the gas tank, about half way up is soft and flexes about 1/2" right in one spot. The rest of floor is solid, rock solid. Can u guys give me the skinny on how hard a job it is and what I might run into if I get this boat as a project boat and try to repair the stringer myself. With a goal to restore it and re-power it one way or another depending on what i find is bad on the motor. I have never done this kind of work and don't know how you would access that stringer without removing floor.