Ferro-Cement Multihull Scantlings

[DennisRB]

What ever happened to this project?

[Corley]

Dennis I dont think we ever heard of any concrete results.

[oldsailor7]

The really environmental property of a ferrocement boat is that when it goes aground it just naturally becomes part of the reef.

[rberrey]

I would venture to say that with modern materials such as composite rebar , kevlar or fiber mesh added to the mix, delvo to put the mix to sleep, a plastersizer added, xypec to make the concrete water proof, we all might be supprised at the end product. I will try to get one of our concrete reps to design a mix and post results. Rick

[rapscallion]

Originally Posted by rberrey

I would venture to say that with modern materials such as composite rebar , kevlar or fiber mesh added to the mix, delvo to put the mix to sleep, a plastersizer added, xypec to make the concrete water proof, we all might be supprised at the end product. I will try to get one of our concrete reps to design a mix and post results. Rick

Add Methacrylates to the mix and you have the cheapest bulletproof composite material I know how to make.... and it's my job to study that kind of thing....

[oldsailor7]

Back in the late 1960s at the behest of a multihull magazine (now long defunct), my company carried out a range of tests on various ferrous cement structures, using (of course) the materials available at that time.
After thorough evaluation we decided that, except for large heavy displacement monohulls, it was not suitable for the stiff, light displacement structures needed in multihull sailboats.

[rberrey]

I agree that cement would not be light weight. But with a mix using composite rebar and mesh, added chemicals , I think you could have a thinner , stronger , and lighter hull than you could have produced in the 60s. Such a mix could expand the type boats ferro cement would be suitable for. Rick

[rapscallion]

Even with superglue, cement has poor tension strength. The awesome compression strength is what makes it impact resistant. Can you build a multi out of it? Yes. But I still feel the best way to go is epoxy and wood. Adagio is over 40 years old, and is still one of the fastest boats on the great lakes. But if you want to build a cheap bulletproof house, use concrete, foam and superglue.

[rberrey]

I,m a concrete man and wouldnt build my trimaran out of ferro, but a new mix with modern materials could give an affordable option to someone . Rick

[tugboat]

Originally Posted by DrCraze

I think I used a little over 400 lbs of cement plaster on the main hull. Given that 10 to 15 percent of every batch ended up in the dirt I would estimate the displacement to be around 350lbs for the main hull alone and about 100lbs for the ama.
This build was intended as an experiment and it turned out to be very enlightening. I'm now having dreams of an 80' proa with a tiki bar

May i ask what the steel content was?..how has it been so far? sea trials?--im still doing a ferr-cement pressure hull in my sub see its progress at http://www.youtube.com/user/porpoisefathom?feature=mhee
mesh or bird netting|?/i like using a polymer modifed cement-called mg krete--it has a 9500 psi compressive strength after 28 days with no water curing...http://www.imcotechnologies.com/canadian/canadian.html- data sheet- concrete repair- 1260 mg krete
thanks!

[rberrey]

9500 psi sounds good, what is the weight cu ft? I would look into carbon rebar or composite mesh in place of mild steel if I were doing a build with cement. Rick