Thank you for the tip about sealing to early, I did not realize you had to wait that long to paint!
You said "The main problems were the welded wire mesh and protruding steel."
I understand the protruding steel. What was the problem with the welded wire mesh?
Best regards
Michael
Brian Cox wrote:
Wilfried schrieb:>--Ferrocement is a concept that is used in yacht building only (not other
engineering ) had a LOT of problems especially rusting of mashing and crackling
due to not optimal use of concrete and lack of proper compactation. It also is
specially problematic for small yachts below 10m due to thin walls while it can
be used with relative good results for bigger yachts.-This is true! Many ferro-cement boats that were built in the 60's and 70's were not built correctly. This is because the methods used for ferro-cement boat building were not fully understood. Now that there is a history of which construction technics lead to problems those problems have been eliminated. The main problems were the welded wire mesh and protruding steel. Rigging and fittings can not be welded to the internal steel matrix, this will cause many problems of corosion. All of the steel matrix and the wire mesh must be completly sealed over with the plaster. Also another problem was created by using metal floats for the plaster finish, this created a shiny hard crust which did not allow any paint systems to work properly (nothing would stick!) Sealing the surfaces too early before the chemical curing of the cement was also a problem. It takes three to four months of curing before the period of hardening and chemical action slows down enough where it will not !
interfear with the chemicals in the paints. A slow curing epoxy once the surface is ready is the first choice of paint but chlorinated rubber will also work. I think the smaller yachts do not perform well because at that smaller size the size to wieght ratio is not advantages to a ferro-cement system, the larger the boat the better ferro-cement can compete with other construction such as wood and fiberglass. Of coarse submarines are another matter. I'm using the ferro-cement as a superstructure and as a large soft ballast tank that will float me nicely on the surface. If built correctly ferro-cement can be bullet proof! There are a lot of successful ferro boats out there.Brian Cox