kingsebi
Well-Known Member
A friend that had a 20m ferro cement boat that he sailed from South Africa to the Caribbean told me that he infused the hull with Coca Cola when it took on water and started to rust. He said that solved the problem.
70s Boats, Any left.
- Thread starter elliotmc
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jwilson
Well-Known Member
We ( Yachtsnet ) brokered the sale of another professionally built Hartley RORC 39 some years back: it had done four transatlantic circuits in the previous ownership, and surveyed well. Not a slow boat at all. The new owner later reported how much he liked the boat.
Everyone has seen horrible bad-amateur-built ferro boats - but there are good ones both amateur and pro built. Done right, ferro has a lot going for it.
AntarcticPilot
Well-Known Member
And there's the rub! Done right includes having cement with the right additives, and determining whether or not the right additives are present is not trivial, and would require sampling of the cement, assuming it's possible - I am not expert in cement mineralogy!
There are modern additives that can make cement self healing - if a crack forms, new minerals crystallise to heal the crack. But I'm pretty sure they weren't available in the heyday of ferro construction, and I think they aren't in widespread use even now; I've come across the concept in scientific papers relating to making buildings more resilient.
Porthandbuoy
Well-Known Member
Didn't the Romans have that sussed a couple of thousand years ago? Self-healing waterproof concrete using volcanic ash if I remember correctly.
AntarcticPilot
Well-Known Member
They did, but the reason it was self-healing was only recently discovered from new excavations in Pompeii that uncovered a working building site. Apparently, they mixed the cement hot, but I forget all the details; it was only published in the last year or so, though, so it should be findable. The work I am recalling worked cold. But the principle is the same - the chemistry and mineralogy promote recrystallisation in cracks.
Cement is basically hydrated silicates, with very complex mineralogy!
Egret
Well-Known Member
Would be interesting if there is anyone here that knows the mix that was used in professionally rendered ferro boats. Compared with timber/plywood. 60 years is not a bad design life. I imagine people would be happy if they thought that they would last that long.
Self healing mortar never lost - traditional lime mortar, used for all brick and stone work right through until recently,
Self healing mortar never lost - traditional lime mortar, used for all brick and stone work right through until recently,
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Rappey
Well-Known Member
DanTribe
Well-Known Member
That film of ferro building on Fambridge brought back memories. I remember those days and many of the characters portrayed.
The large yacht I think was called Juanita. She was winched on greased skids as shown up through the pub car park and down the road., took several days I think, and the crane was never the same again.
Snowgoose-1
Well-Known Member
Do you also remember Bill at Tollesbury ?
Affectionately known as " Portland Bill"
who built ferro smacks .
Tamar
Well-Known Member
There is a concrete 90 seater ferry operating in Cardiff bay.
AntarcticPilot
Well-Known Member
It's worth noting that it's not a new idea. The Maritime Museum at Bremerhaven has what they label as the oldest concrete boat; I can't find it online (it was a small boat), but Paul Kossel is from 1920. Vast numbers of concrete lighters were produced in WW2 for the invasion fleet.
AntarcticPilot
Well-Known Member
I remember that someone posted on it on these fora. Plasticizers and additives to control setting time come to mind.
Rappey
Well-Known Member
Fine lime free washed sand and sulphate resisting cement mixed at 1:1 ratio . Once the hull is plastered it needs continually spraying with water for 1-3 months while curing.
Egret
Well-Known Member
That's very interesting - a very strong mix - can see that the 3 month curing time sprayed with water would have been key to crack control - and additives more recently maybe - A long time though to be sitting in a yard taking up space before fitting out - I had been wondering if they maybe used fly ash in the mix to control the temperature rise during setting and curing to reduce chance of cracking - like for big bulk pours - so the very strong mix is the opposite direction. Presumably different builders will have done it in different ways. Whatever they did, it worked well generally.
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Rappey
Well-Known Member
The oldest known ferro boat was built in 1848 in france. It is a rowing boat built using mesh and cement. It still survives today in a museum.
The "violette" built in 1919 is the oldest still afloat but I'm not sure if it still floats or just sits in the mud. She currently forms part of a breakwater in Hoo, Kent.
Ships and barges were generally built with concrete which is a little porous.
Leisure boats were built from ferro cement which is mortar without any aggregate and is non porous.
Rappey
Well-Known Member
Spot on . One month is the minimum but 3 months makes it stronger reaching full strength at around 10 years.
I have come across fly ash and pozzalano as additives. There are different ideas about whats needed in the mix but most the time additives are just not needed.
A hartley ferro hull Is around 20mm thick with 8 layers of mesh.
Hartley boats was established in 1939 supplying plans . They claim over 100,000 built to date.
Windboats on the east coast built some beautiful ferro boats.
Ive read claims that more ferro boats were built in the uk than anywhere else.
Many were built in back gardens. Some collapsed when being lifted out by a crane .
The badly built ones are mainly gone. The good ones just blend in with the rest of the boats and most think they are grp.
