Cast Iron keels were common
In the early 1970's when these O'DAY 23's were built it was very common for keels to be made of Cast Iron, the Paceship 23 of that time is the same way. My guess is that it was done for cost savings, and so John Deknatel of C. Raymond Hunt Associates specified Iron for the keel when he designed the boats. Maybe O'Day and Paceship approved it or even asked for that? Just to really add some spice to the discussion....the pop-top mechanism was designed by a pop-up camper designer, Andy Kostanecki!Bill, I see that you are from Providence, if you need to talk to Rudy at D&R, or order parts (he has the CB for the 23) you may be better off taking a ride over to Assonet, MA on a Saturday morning and visit Rudy. I have done that many times and if you think he is helpful on the phone, he is even better in person. He is busy, but has helped me with information on several repairs with my DS II. He might......don't count on it...but might even come visit your boat to give some helpful advice for getting what's left of your CB out of the keel. The original CB for the early (cast-iron keel) version of the 23 was hollow and I think could leak and might fill with water, then freeze over the Winter and crack.......it also looked a bit fragile side-to-side judging by the one that Rudy showed me one time. I think he makes them semi-solid to make them stronger and more able to be ground thinner if they bind.