Here in 2014 after the 2006 repair, I coated the keel in Black PL
You still see the sanded Permaflex is well stuck to the main hull, however it did not stick to my oak keel. My keel the wood is somewhat blackened and charred in appearance, so the wood surface may have just not been clean enough. However the Black PL S30 smeared on with a 6 inch trowel is just like frosting a cake and totally waterproof. And it seems to have adhered well to the keel.
If you mix 1/32 inch fiberglass milled fibers 30% to Black PL 70%, you get a real tough rubber membrane. I did that on the bow in 2014 going back 10 feet as an experiment, and have been very happy with it.
It is very easy to use and apply. The keel I did not put in the fibers. I do like it mixed with fibers. Someday I might recoat the entire hull in Black PL and the 1/32 milled fibers. But mostly I like to experiment, not that it needs that.
I also discovered to seal up big cracks in keels, as in where the wood beams intersect, you mix Black PL saturated into white cotton balls and stuff it into the seams. It seals it, works great. See a wood boat is going to want to move, and these type sealers I use will move with the wood. Black PL when mixed with milled fibers reminds me of car tire rubber.