The excavation begins.

My home away from home.  That vac was totally inadequate, and I needed my huge shop vac.  

The patient prepped - I elected to cut out the side of the settee for access.  I will replace the panel, but leave the oval slot you can see for ventilation.  

Here is a "core sample" of the top of the keel stub, in the area where the bolts bear.   Glass is 3/8 thick.   A bit thicker under the forward keel bolt.

You can see the top of the keel stub cut away, and the first few holes drilled into the putty with a spade bit.  The stub is 24" deep, around 7" wide and around 24" long.  I ended up drilling holes about 3" deep, then using a 4-foot crowbar bashed into the hole to lever and break away the putty.   Repeat for two full weekends...

A few inches down and a long way to go.  See the black. moldy fault lines, and the piles of rubble accumulating on the deck.  You can almost see the starboard side of the keel box, which had separated from the putty block.  This is where the water would accumulate, though there were cracks throughout, and the putty itself was damp throughout even the pristine solid parts.  Talc-filled I think.  Ugly, but I don't think it was deteriorating badly - certainly not like I've heard from others.  

Are we there yet?

Almost done.  the bottom was in surprisingly good shape, and the putty was difficult to remove.