Your keel looks a lot like the keel on the LeComte Northeast 38, which I know a bit about, so I'll share. It could be that it doesn't apply to yours, so it's a case of "keep in mind what you paid for the advice", but if it helps, that's great!
Our boats are also externally attached lead, also built in Holland, also have that strange triangular filler at the front of the ballast, and also have the keel bolts and their nuts buried in glass inside the water tank. Several owners have been concerned about the attachment of their keels, since the boats are so old and everyone likes to check their keel bolts out from time to time - having (in my case) a boat that's 43 years old and never checking the keel bolts is a bit unnerving!
That said, only two owners that I know of have dug out the bottom of the water tank to see what's up, and both of those have reported back that all is well.
One of the Northeast 38's recently went ashore over a reef in the Bahamas, which did a bunch of damage to the bottom of the keel, as you can imagine. Probably more remarkable is that it didn't kill the boat, or even render it unusable - the story is here:
http://www.lecomteowners.com/index.php? ... view&id=69. As a result of the accident, the owner wanted to get a good look at the keel bolts, which he did. He found that the only damage was to the bedding between the keel and the hull - in the area that your "gap" is - and that the fix was to lower the keel, fill the gap with epoxy, and tighten the keel on again while it was wet. Or something much like that. His description of it is in the forums on the site linked to above - as is the shop which did the work, who you might call up to discuss it with. Here's his quote regarding where the work was done: "Secondly, if you ever need help in south central Florida, Riversie Boat Yard is a good place to go." They'd probably know as much about it as anyone at this point, unless you do better with the folks on the Tripp Lentsch site.
I don't know if this helps you out at all or not. I guess if it were me I'd be cleaning that out to see if the ballast is actually wagging around under the boat, and if it is I'd be getting at the keelbolts to drop it, fix the joint, and re-attach it. Or at least to tighten the bolts. If it's not wagging around, I'd probably just fair over the crack and sail until there was a reason to do more. People who know more than I do about it have told me that I'll have plenty of warning before it becomes a real issue - if one bolt should go, I'll see the results and be able to deal with it at the next haulout.
Good luck with it - I'll be curious to hear what others have to say, too!
Cheers,
Chris[/url]