Fill the crack and fiberglass over
There has been some commentary in the past forums on keel leakage. I had leakage on my 1975 H30. The strong nearly unanimous choice (including Hunter Service) was to clear the joint, fill and fair with a structural filler, I used West Epoxy with structural filler after clearing the joint with a Dremel, fiberglassing over the joint(wide strips first, thinner strips later, and finally coating with another filler for fairing and barrier coating. As long as the bolts are tight there should be no problems with cracking at the seam, but I don't have alot of time on the water yet and no groundings or collisions to test my work.