An international revolution is taking place in boat building, instigated by concrete, which is becoming an increasingly popular material in the construction of water crafts of many types. The world tonnage of concrete yachts, power boats, and barges is growing rapidly.
There are three basic methods of reinforcing concrete boats. One of the more popular ones was developed by Dr. Pier Luigi Nervi and called ferro cemento. Shortly after World War II, Nervi built a large fishing trawler, a 165 ton schooner and a ketch-rigged yacht. All proved structurally sound. Having to proceed with projects in other fields, the Italian architect did no further work in boat building.
About 20 years later, W. Sutherland, a New Zealander, and one or two others began building Nervi-type concrete vessels commercially. Ferro-cement is a combination of several layers of light steel mesh and spaced steel rods with a well-graded rich mortar. Because the diameter of the steel mesh is so small- usually about 19 gauge- only a thin covering of rich paste is needed to protect the steel. There are many advantages to building with ferro-cement. It is almost always cheaper to build 30 feet plus vessels in ferro-cement than in wood, steel, or fiberglass.
Although ferro-cement has a fairly high density per cubic foot, a yacht over approximately 45 feet is actually lighter when made of this material than of wood or steel. Other advantages are: about 12 percent of the space of a typical yacht can be saved, since bulkheads and other features are eliminated; it has the best fire-resisting properties of all boat building materials, including steel, which buckles; it is absolutely leak-proof; maintenance is greatly reduced; and boats made of ferro-cement can be easily repaired.
