Here is a site you may find useful:
The World of Ferroboats
I probably have an unfounded fear of ferro boats. Just don't understand how you can build a boat out of cement with imbedded carbon steel (rebar and chicken wire) and have it last, and apparently some have lasted. How do you drill for and install seacocks? Fiberglass is so easy to work with, I would be lost working on a ferro boat- I am no stone mason. How do you repair
the boat if the reinforcing steel starts to corrode? Seems one day you could have what you think is a good boat, and the next week you finde the reinforcement is no longer adequate.
Just so many unknows for me.