Ok here ya go,I had a friend who owned a cement boat I replaced the cockpit deck and then we decided to cut the cockpit wider as she was a bit cramped and the seat was so wide you could not sit easly. We took carbrindum blades and began to cut the 5/8" thick mud one blade two,three,four and we had only gotten one foot cut. We finally got a diamond blade and with it wet cut out the cockpit in about four hours. We took a piece of the cement and took a hammer to it. We beat it as hard as we could and it would not break. We got a small maul and laid into it nothing nada. That was the toughest stuff I ever ran onto other than steel. One more thing I cant remember where it is but a freighter went aground when she was fairly new maybe in the 50ies and last I knew she was still on that reef and had outlasted many steel hulls and was a land mark.I saw some junk boats built in the sixties and seventies in south Florida but like they say find the history and if the rebar is OK go for it.