[quote="$kipper68"]So, I catch a Star Fish and...WHAT? Plane it? Sand it? Mulch it into goo?
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I was merely referencing how starfish and echinoderms in general, have skeletons analogous to the mesh of ferrocement-boats, have flesh growing on the inside and outside of their skeleton.
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[quote]
Why do you continue to try convincing us to get a cement submarine?
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Concrete/ferrocement can be made into many different kinds of structures,
including monohull boats, pontoon boats, buoy's, docks, oil-rigs, and floating islands.
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I appreciate the response about the skeletons being made into a product.
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cool :-), yep that's just about any skeleton of any marine life, that has a calcium-carbonate skeleton.
[quote]
There is no value, when repairs are needed NOW.[/quote]
lol, well obviously you could have some prepared cement/aggregate onboard.
Just like if you had a wooden boat you'd likely have some plugs aboard.
If you need to do repairs underwater can use a submersible mix like SUBAC http://www.subac.com/
Though many fast-drying hydraulic cements can work.
[quote="ka8uet"]It seems to me that I have read somewhere that the failure of most concrete is caused by the rebar becoming rusted through some exposure ( it doesn't take much!).[/quote] actually it usually takes many years of exposure.
Also note that steel boats are even more prone to rust-damage since they don't have concrete shielding.
[quote]
because it expands as it rusts, it breaks the concrete from within. Homebuilt concrete boats seem to be particularly prone to this, since often they are not properly engineered. [/quote]
it depends on the materials used and thickness of the concrete.
For lowest maintenance it's best to use galvinized or otherwise rust-resistant rebar, have a thick layer of pure concrete/aggregate on the outside, to lower permeability to the rebar, and have some sacrificial anodes as with any metal boat.
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However, as properly constructed concrete boat should not be any more lsubject to failure than any other properly constructed and maintained boat.
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Even a poorly constructed ferrocement boat, is often cheaper to maintain than any other kind of boat.
Thing is, that even if it cracks, it's a very simple task of applying more plaster.
by contrast to the amount of effort required to replace a plank or fiberglass.
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Given proper maintainance, they will all last. Given none, they will all fail.
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after a much longer time than any other hull material.
As illustrated by the WWI boats, even with no maintenance they have long life expectancy.
Technically if a water-tight boat sinks, it can simply be repaired, bailed out, and put back into operation.
Boats that are beached are also just as easy to repair and put back into operation.
Fiberglass, metal or wooden boats however, quickly degrade and become unserviceable.
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Therefore, it is the maintainance of a given boat that will decide her lifespan, not her material. "Nuf said.[/quote]
The first ferrocement boat ever constructed is still water-worthy,
the first fiberglass/metal one made is long gone.
You made generic comparisons without looking at either timeline or cost.
Fiberglass boats have lifespans of about 30years, after that the glass fibers are mostly broken and resin is degraded, so it becomes increasingly more expensive to do repairs.
Steel boats only stay afloat because they have teams of maintenance workers.
Wooden boats rot and leak, with speed depending on environmental conditions. Wood is biodegradable, expensive and relatively difficult to work with.
Fiberglass, wood, and metal require a large set of (power) tools to make repairs.
Concrete boats are so simple to make children could do it, with the same skill set they use for play dough. Here some middle-school children make concrete boats http://www.youtube.com/watch?v=UWWCRLGunqg
note that those boats don't have metal components.
[quote="$kipper68"]So, now I will keep all the ecto skeletons from my seafood dinner.
:mrgreen: I really cant take this thread showing up again. To use the methods that are being proposed here are beyond Jules Vern...even he used metal. :roll: As far as wood being limited-check out the coral bleaching..UGH- head slap! :lol:[/quote]
*shrugs* by having boats at sea we'll be making more eco-regions for sealife to grow. In fact the very same corals could potentially extend the seastead and do repairs, simply by growing on the hull.
Though there is already plenty of limestone, which was created after billions of years of calcium-carbonate deposits. by contrast we don't have billions of years of dead wood laying around.
Another interesting repair-ability is biorock or seacrete, which can be formed by passing an electric current along the mesh,
[quote="wikipedia"]
http://en.wikipedia.org/wiki/Seacrete
It works by passing a small electrical current through electrodes in the water.
The structure grows more or less without limit as long as current flows.
Biorock accelerates growth on coral reefs by as much as fivefold and increases coral survival. Biorock can enable coral growth and regrowth even in the presence of environmental stress such as thermal pollution, i.e. increasing water temperatures. When mixed with construction aggregates, it can build components on the sea floor or on land. Biorock represents the only known method that can sustain and grow natural coral species using only basic conducting elements, typically of a common metal such as steel.
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So would also have to add that ferrocement is one of the most eco-friendly hull building materials.
