"This site is devoted to the promotion of Ferroboats as well as a base for all matters Ferro in the boating world. Ferro-cement is the name given by English speaking people to a boat building method using steel wires covered with a sand and cement plaster, patented in 1855 by the French, who called it Ferciment. Ferciment boats built before 1855 are still in existence and at least one is still afloat. The Italians called the method of construction Ferro-cemento. The British, New Zealanders and Canadians who promoted the method for amateur construction called it Ferro-cement, often referred to as "concrete". It is the cheapest and easiest form of construction for boats over 25 ft. And apart from strip-plank composite construction, it is the only viable material for large round-bilge boats within the amateur capability, without the requirements of special tools or a weather-proof building."
One man's labor of love (building a ferrocement boat): SEAFALCON.ORG
One bit of recent research regarding "Aluminum Bronze Alloy for Corrosion Resistant Rebar (link updated Aug 8, 2010)" might be of interest to those considering building a ferrocement sailboat:
This project evaluated aluminum bronze alloy as a possible alternative to steel for corrosion resistant concrete reinforcement. Rebars from aluminum bronze alloy were fabricated for laboratory and field evaluations. Initial tests showed rather low mechanical properties for alloys as compared to steel. Further work focused on improving the strength and mechanical properties of the alloy by optimizing its composition and fabrication process. The process eliminated the hot rolling operation and entailed direct continuous casting of aluminum bronze to a near net size and shape of rebar followed by cold drawing the bar to finished size and shape. The cold drawing operation increased the strength of aluminum bronze rebars close to that of mild steel rebar, meeting the ASTM specifications (Figure 1). In corrosion tests, the aluminum bronze alloy showed high resistance to seawater corrosion as compared to mild steel and ductile steel (Figure 2). Cost analysis of aluminum bronze rebars showed a cost of $0.85 per lb. as compared to $1.20 per lb. for stainless steel at current metal prices. The final report is available from the National Technical Information Service (NTIS # PB97-141972).