Back in the seventies, quite a few boats were built from ferro-cement in Norway. These were mainly large boats, well over 30ft. Old Colin Archer pilot and rescue boat designs were well suited for the material. Its round curves were no problem in FC and their double compound curves (‘egg shape’) made stiff and strong hulls. In addition, designs from Hartley and Samson were used. They were all sealed in epoxy and anodes were also fitted, so they have lasted remarkably well.
A crucial factor was how the plastering was done. I participated in the plastering of two boats, one Colin Archer and one Hartley. In both cases, the practice was that two and two people worked together. One pushed all the cement in through the mesh. The one on the other side (inside) was monitoring, calling out when there was enough and then faired that side. This method (as opposed to pushing cement from both sides) ensured that there was no ‘empty’ layer in the middle, which later would collect water and develop frost and rust problems. Later, when we drilled holes in one of the hulls, the surface was like porcelain - no cavities at all. (I once came across a second-hand FC boat which appeared to have not been plastered properly, and advised a potential buyer to shy away from it.)
If I were to buy a second-hand FC boat, I would need to be sure that the steel and mesh structure was good, but above all, I would need to know that the plastering had been properly executed. If I could tick ‘ok’ in both those boxes, and if I fancied big cruisers, then FC would be my preferred material - no leaks, no rot, no rust no osmosis, and very little maintenance.
Unfortunately, those who built their FC-boats (cheap and easy, right?) soon learned the hard way that only a third of the job had been completed when the hull was finished, so many ran out of steam before the projects were finished. Big boats always means lots of work and costs. Svein Magnus Ueland took 20 years to finish Samson (getting married and raising children in between), but at least he ended up with a great ship which really sails.
Cheers, Arne
(PS: Svein Magnus spells his name Svein, not Svenin.)