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Old 19-04-2016, 17:48   #76
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Re: 21th Century Ferrocement Yacht Hull Technology

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One of my favourite ferro boats is Quais Quais. Home-built in the 70's left Vancouver 1980 and returned 2013. One leg from Durban to Nelson with no stops took 4 months at sea. I think they averaged around 3 knots. They were reported lost but turned up at Port Nelson one night a bit lean but otherwise fine.
I remember meeting them in cape town in 89, they were having problems with all their teeth falling out after an extended cruise of the indian ocean!.

seem to remember meeting them again in the pacific quite a few years laterr the boat was a grey Samson FC double ender if I remember correctly,french Canadians,nice people
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Old 19-04-2016, 18:17   #77
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Re: 21th Century Ferrocement Yacht Hull Technology

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(As for the Hitler reference, I knew it was touchy because of his overwhelming identification with Ultimate Evil, but I couldn't think of a worse idea than starting World War II)
I understood, and I think it's redicilous to compare WWII to boat building ...
Now matter what the idea or plan is
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Old 19-04-2016, 18:18   #78
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Re: 21th Century Ferrocement Yacht Hull Technology

It might be worth looking up the orignial Helsal, she was a very experimental FC craft. Post stressed concrete and she might have also had fine stainless steel wires incorporated into the concrete to reinforce the surface layer above the mesh. She went on to win the sydney hobart.

But to be honest I cant see the benefit of using such an experimental method to build a large boat. The hull is a tiny fraction of the work and cost, so economizing on the hull is not the best way to save money long term.

Building the hull in sections glued together is not a good idea for offshore work IMHO. The biggest benefit of all the modern construction methods is the ability to make the entire hull and deck into a big monocoque structure with no weak points and a minimum of joints. And even on a GRP boat the hull deck joint can be a big source of problems, as can the keel/hull joint. To add extra joints is asking for problems.

On a traditional FC hull, a big source of problems is the way the deck joins the hull, if the deck is made from plywood. Ideally it is heavily glassed over onto the hull to make the joint watertight and strong.

Ive seen a couple of fer -a- lite polyester plastered boats. They seem to have stood up well over the years, and are far lighter than traditional concrete.
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Old 02-07-2017, 17:27   #79
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Re: 21th Century Ferrocement Yacht Hull Technology

So even if Reactive Powder Concrete (RPC) seems not to be the 21th Century Ferrocement Yacht Hull Technology, there are interesting new concrete materials to work with just entering the market.

German Universities of Dresden and Aachen have found a new concret supported by carbon, which allows for very thin materials, because ferro concret needed a certain minimal width to cover the iron and prevent rust. As the carbon can not rust, with can be very thin meaning just a few milimeter.

https://en.wikipedia.org/wiki/Textil...orced_concrete
German names are: Textilbeton (beton=concrete) and Carbonbeton
And there are lots of German language vids on Youtube explaining the material.

There is a concret boat rowing competition between Universities, a university submarine from concrete, people producing furniture like tables or arm chairs from that material.

It is allready used for public bridges and will be an ideal repair material for older concrete buildings. Probably we will see a yacht as prove of concept in a few years from one of this institutions.

The material could be interesting for building the deck and superstructures or to build the furniture inside the boat.
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Old 03-07-2017, 05:33   #80
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Re: 21th Century Ferrocement Yacht Hull Technology

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So even if Reactive Powder Concrete (RPC) seems not to be the 21th Century Ferrocement Yacht Hull Technology, there are interesting new concrete materials to work with just entering the market.

German Universities of Dresden and Aachen have found a new concret supported by carbon, which allows for very thin materials, because ferro concret needed a certain minimal width to cover the iron and prevent rust. As the carbon can not rust, with can be very thin meaning just a few milimeter.


There is a concret boat rowing competition between Universities, a university submarine from concrete, people producing furniture like tables or arm chairs from that material.

It is allready used for public bridges and will be an ideal repair material for older concrete buildings. Probably we will see a yacht as prove of concept in a few years from one of this institutions.
25 some years ago, we had a concrete canoe competition in college and it had been going on for years before. It's not a new idea.

https://en.wikipedia.org/wiki/Concrete_canoe

It's more than just covering the reinforcement. In reinforced concrete design, the idea is to use the concrete to resist the compression loads and the reinforcement to resist tensile loads. Realistically concrete is not water tight so keeping the steel dry isn't an option.
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Old 03-07-2017, 15:46   #81
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Re: 21th Century Ferrocement Yacht Hull Technology

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It's more than just covering the reinforcement. In reinforced concrete design, the idea is to use the concrete to resist the compression loads and the reinforcement to resist tensile loads. Realistically concrete is not water tight so keeping the steel dry isn't an option.
True re design strength but properly designed and built ferro hull does keep the steel dry. Otherwise the many 40 or 50 year old ferro boats cruising today would not be the low maintenance hulls they are.
Two factors, 1st the very high cement content, secondly the very good adhesion of paint to ferro. If the paint is scraped off the high cement content(low porosity) still prevents the chlorine from getting to the steel.
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Old 03-07-2017, 15:57   #82
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Re: 21th Century Ferrocement Yacht Hull Technology

To be precise, it is Chloride, not Chlorine that causes the corrosion, simply CO2 in the atmosphere would suffice.
The high alkaline content of the cement is the agent to counteract this.
The use of a high Portland Cement content is the factor that provides the watertight nature. The Epoxy is an extra seal and a finish coating for appearance, it is the Portland Cement that does the work provided it is fully bound to a decent armature.
Roger
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Old 04-07-2017, 10:18   #83
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Re: 21th Century Ferrocement Yacht Hull Technology

I just wanted to point out, that we may see a revolution of concrete and carbon fiber during the next couple of years that may give new options for people, that like cement boats.

The carbon textiles and carbon rods will get massproduced and get cheaper in a way that it may be interesting for home boat builders. Also there are developments concerning concrete. It woudn't be the same used 40 years ago.
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