On Tue, 10 Jun 2008 08:59:06 -0700 (PDT), "
wrote:

BTW, the boat is an early J-35 (fully cored), and apparently it had
grounded previously.

Yuck. It looks like the hull failed, not the ballast keel/sump
joint. I suspect the "outsideness" of the ballast was not a
contributing factor.

Yes, J35s had notoriously weak keel attachments. They depended on a
steel plate glassed into the laminate to provide sufficient hull
strength. One hard grounding was usually enough to shatter the
laminate in that area leaving the keel/hull area vulnerable to flexing
or complete failure. I personally know of several boats where this
happened. Repair required almost complete removal of the interior.