Happens all the time. If you've reviewed our web site then you can see some directions on the application of CPES and the follow-up projects, if necessary. Get back to us if you have additional questions. The stern seam can be solved with a combination of CPES and 3-M's 5200 sealant. Not a big job, assuming you don't want to re-glass.
Epoxies are expensive, but they are the best.
If you decide to proceed, you might consider sending us a few pictures of the damaged areas. That way we can look and be specific about what you need to do. We've repaired a lot of boats. Come back if you have additional questions.