wrote

They are heavy for their length though and you'll probably find that
you can carry a lot more sail then the fiberglass boats.

But a LOT less than a cored glass boat of the same shape and equal
displacement with the weight saved in the hull carried as ballast. The
glass boat will also be much stronger if some of the weight savings is used
to add material.

I once figured out that a typical ferrocement hull was the material
equivalent of 1/64 of an inch of steel on each side of a 1/2 inch concrete
core. Does that sound like a way to build a boat? Worse the steel, which
should be the tensile material on a thin shell, was on the inside and the
concrete, a material most effective in compression, was on the outside.

Strong as wood, heavy as steel, about sums it up. That doesn't mean you
can't built a good boat out of it, just that it will not be as strong or
well performing as other materials which are not significantly different in
cost when you consider the full investment.

--
Roger Long