However, if done right, I'm led to believe that they get stronger
every year they are in the water.


In theory, yes.

You have more faith in f-c than I. I'd never go offshore in one, despite
knowing it was built properly and by a pro. I just don't think it's a
reasonable building material, despite what some aficionados claim.


It's reasonable. It just has a number of problems. All boats
are a compromise.


Peter wrote:
Well, from an engineering POV it's the heaviest commonly encountered
building material for the structural strength.

Hmm, that depends. It's tremendously strong in compression.
The problem is that boat hulls are not in pure compression.

... It does work, but IMO
the boat needs to be pretty big & heavy displacement to overcome the
inadequacies of the parent material.


Definitely. Nobody ever built a light boat from ferro-cement.

The trap people fell into was the snake oil sales pitch that you'd end
up with a cheap boat. Wrong, you ended up with a cheap hull and only
then if you put a zero dollar price on the labour that went into it.


Yep, most people who have stars in their eyes about building
a boat refuse to believe the advice that says the bare hull
is only 20% of the labor and less than 10% of the cost. Most
ferro-cement boats (and of any other material FWIW)
remain uncompleted botches and are eventually chainsawed &
landfilled. Or else they are turned upside-down, a door is
cut thru the side, and they become storage for garden tools
for whoever buys the house from the widow of the builder.


I might buy one, if the price was right, but my valuation would be the
residual value of the installed equipment minus the cost of hull
disposal.


Excellent plan.

Funnily enough, a 30 y/o f/c hull with no sign of rust bleed etc is
probably fine for a long time, provided you don't crack the shell & get
water into the wire armature.

You can also ultrasound the hull. One of the problems of
ferro-cement is that it has very poor impact resistance, and
any cracking of the shell leads to total failure. Bad idea.

I've wondered if it would be possible to sheath a f-c hull
in a thin layer of fiberglass... maybe using dynel cloth? to
improve the odds on this.

Once the hull starts to show rust bleeding thru (either
outside or in) it's toast.

.... Friend of mine bought one that had been
pro built some years ago, for coastal sailing, cheap. So far he's had 5
years out of it without problems.


Good luck to him.

Fresh Breezes- Doug King