Looking at 94 Passage 42 with small crack at keel/hull joint

[sailor5017]

Had same kind of cracking on 91 37.5 every hail out I would open the crack with dremel tool and fill with an epoxy filler compound. The crack would reappear the next years haul out.
the crack was caused by flexing of the hull and then the fairing compound would crack.. Gouged out crack again and filled with 5200 which has a little flex no problem after that..

 

[splax]

I have a 1999 420 that had the same thing. I repainted it for several years until after a hard trip down the coast several days. The aft keel bolt (the long one that is smaller than the 8 big ones) started leaking. Since Hunter used an epoxy resin to glue the keel on, it couldn't be removed by the heated piano wire method and had to be ripped off. The keel sump had old damage at the aft end that had been filled by a previous owner with bondo. The keel sump had to be re-glassed and levelled, then the keel was reseated in 5200. Very expensive and long process. Make sure your surveyor looks at this very closely. I would steer clear of this if I were buying.

The bondo repair seems to be a likely culprit since it may not be flexible enough to handle the movement of components underway. A repair using fiberglass cloth and West system epoxy is strong and flexible. Fairing using West and fillers will give you that smooth paintable surface.