Don;
The cracking indicates that there is movement in your keel joint. Once the boat is launched, gravity will pull the keel away from the hull - possibly compromising the seal. Also when you sail the boat and it heels, there is a very significant torque applied to the joint.
I had a similar problem on my 1978 E-34. Every spring I would apply 5200 to the outside of the joint to keep the water out. It got a little worse each year until eventually the joint seperated.
What had happened was that the fiberglass holding the keel support had failed and the leading edge of the keel dropped about 1/4 of an inch. The aluminum keel support held the keel, and it looked very much like your photo. The resulting leak required a 2000 GPH pump to keep up with the inflow of water until I could emergency haul the boat - the little 500 GPH pump couldn't keep up and the boat was actually sinking.
The repair was VERY EXTENSIVE - hundres of hours, lots of fiberglass and aluminum, lots of fairing. In the end, the repair was successful and I just finished a season (the first of six) with no gaps whatsoever in the keel joint.
Once that joint is compromised, it will worsen and eventually the keel will part. In my case, this was caused by delamination of the fiberglass around the keel support.
Best Regards;
-Steve