I read the following information on Ferro Cement Yachts at: Marine surveys, Captain Alan Hugenot San Francisco, CA Home
ANALYSIS: It surprised me that all these concrete ships seemed to remain indestructible after 60 to 90 years and yet they had received almost no maintenance. I know from my own first hand experience that steel, aluminum
or wood vessels given the same neglect would have deteriorated and disappeared in less than 20 years. So, I began to seriously re-consider and research
ferro-cement, and I was amazed with what I learned.
NEARLY INDESTRUCTIBLE: Ferro-cement is nearly indestructible when properly constructed, and it is very popular as a work boat construction material in Europe
and the developing world. In France
, today, there are several ferro-cement vessels still afloat which were built before 1855. Outside the United States ferro-cement construction is fairly standard, and in developing countries ferro-cement is economically competitive with steel, aluminum, wood, or fiberglass construction, simply because it is less expensive than steel, aluminum and FRP, and wood is now becoming more and more scarce.
ECONOMICAL: Further, ferro-cement boat construction only requires locally available materials and a large supply of hand labor. Consequently, local semi-skilled jobs can be created using ferro-cement construction without the need for extensive tooling or welder training, and the finished boats require only minimal maintenance.
Ferro-cement?s excellent suitability for boat construction is recognized by the U.S. Navy
? s, Ferro-Cement Boat Building Manual (NAVSHIPS 0982-019-1010) issued by the Naval Ships Systems Command (now NAVSEA) in 1972. This three volume text covers the entire ferro boat building process, and forms an excellent basis criteria for marine
surveys of ferro-cement boats.
IMPERVIOUS TO WATER
PENETRATION: The great advantage to ferrro-cement is that it is completely impervious to water
penetration. It simply does not get wet on the inside, Consequently, when the mortar covering any embedded metals is of sufficient thickness (over 9 mm or 3/8?), tests have shown that the embedded metal is fully protected from chemical attack by the impervious cement, even when full immersed in a corrosive such as salt
water. In other words ferro-cement is better protection than many paints.
Unfortunately, this fact is counter intuitive to most people. Most folks are not schooled in the physics and chemistry of structural cement, so they nearly all believe that cement gets wet all the way through when it is immersed in water. They never realize that the wet look is only on the surface when the cement is properly formulated.
Actually, when ferro-cement is properly mixed and formed, it becomes an impervious monolith that water cannot penetrate. As Joe .P. Hartog, the professional Naval Architect who designed many ferro-cement vessels stated clearly in a technical paper on ferro-cement which he published in 1988:
?Because well-made ferrocement is impermeable (waterproof), there should be no need for painting?. Quoted from UNDERSTANDING FERROCEMENT CONSTRUCTION, (?1988, ISBN: 0-86619-284-0)
Unfortunately, this popular mistaken belief (that water always penetrates clear through cement), creates an additional unfounded fear (which takes on the form of an urban legend along the waterfront), that the chloride (salt) dissolved in sea water will penetrate (soak) through a cement hull and attack any metals imbedded within the structure. But, this is also completely untrue.
After reading the above information on FC built boats, I for one will be looking at professional built FC yachts when it's time for me to step-up from my plastic 22'er to something more substantial
provides lots of other helpful information on a number of boat subjects: Marine surveys, Captain Alan Hugenot San Francisco, CA Home