Grancrete as a building material

This stuff looks like it would be good for boat building

Essentially its spray on concrete

http://grancrete.net/grancrete_overview12.htm
http://grancrete.net/grancrete_specs12.htm

 

All the concrete boats suffere from the same problem ,

there is NO WAY to check the condition of the hull once created.


No survey , no insurance , no resale.

NO VALUE for a heck of a load of work.

FAST FRED

 

This stuff is great as it bonds to itself and any pourous material I will be building a boat out of this, spray on foam, and a bamboo frame myself as a second faze to a five year plan for my business. As the hull will not be solid concrete just an outer and inner layer it will be easy to check the condition of the hull any cracks from impact and you just spray or trowel a repair unlike normal concrete, again, this will adhere to itself so no need for all the chicken wire and such. It will be so cheap to build and so light/ strong damn the insurance and if you put in on the market at half the price of boats half the size I bet you will find buyers! When I start building it will be in the SF, CA area anyone want to help?

 

Grancrete boats

This stuff is great as it bonds to itself and any pourous material I will be building a boat out of this, spray on foam, and a bamboo frame myself as a second faze to a five year plan for my business. As the hull will not be solid concrete just an outer and inner layer it will be easy to check the condition of the hull any cracks from impact and you just spray or trowel a repair unlike normal concrete, again, this will adhere to itself so no need for all the chicken wire and such. It will be so cheap to build and so light/ strong damn the insurance and if you put in on the market at half the price of boats half the size I bet you will find buyers! When I start building it will be in the SF, CA area anyone want to help?

 

Good luck!

I'm not convinced that any existing spray-on material is going to have enough strength on its own -- without any reinforcing matrix -- to deal with the stresses on a boat hull in serious conditions. I don't like the idea of foam inside concrete either, but maybe that's just me.

How are you going to find buyers when the boat won't be insurable? It doesn't matter how cheap you can sell it, because people won't buy it unless they can insure it.

And what do you plan to do when one of these boats breaks apart and kills or seriously injures someone and lawsuits are filed against you for making claims that the boat is 'safe'? The material manufacturer is certainly not going to back you up since they do not specify its use in the construction of boat hulls ... and wisely so. Without 'boat hulls' being an approved use for this material, how are you going to insure yourself?

In case you haven't noticed, production boat building is moving overseas to countries with much cheaper labor than the USA. You might think that using this material will make your boats cheap to build, but I have my doubts.

I don't like to discourage practical innovations, and maybe this material is every bit as good as you seem to think it is. However, I have serious doubts about the suitability of this material for your proposed use. It may be fine for terrestrial buildings and water tanks and such, but I would never build a boat out of it -- not without substantial embedded reinforcement -- regardless of how well it *might* hold together without it -- and I certainly wouldn't encapsulate any foam in between two layers of this stuff.

It's always nice to dream ...

 

As in any relatively untested material, application with the use of reinforced, lightweight concrete, either sprayed or conventionally applied, must be engineered for the end use.

My understanding of this particular material is it's a top coat of fiber reinforced light weight concrete. There are several different manufactures Grancrete is one of them.

This material was originally developed to line the walls of tunnels, which it does quite nicely. It's structural applications as a stand alone product or in a sandwich type construction would be limited.

Though it is a little different then conventional concrete, it still has similar physical properties. It is about 20% lighter and the reinforcement adds to it's compressive strength and controls expansion, but it's still concrete.

Without a reasonable engineering background, you'll be hard pressed to take advantage of the physical qualities of this product and incorporate it into a hull shell. I do think it could be done, but question the advantages that may seem to be gained.

For example you'll need about a 1/2" thick exterior skin to insure it's waterproof, which wouldn't be especially light, nor particularly strong without a substrate or internal reinforcement other then the fibers found in the concrete itself. Sprayed over a plywood substrate or a metal matrix (such as typical ferro layups) then you'd have a much better opportunity, to take advantage of the physical properties of this material, while retaining sufficient stiffness for a load bearing structure, like a boat's hull shell.

Do yourselves (both Waterbeatsrock and Packeteer) and have a talk with the manufacture. You'll likely be able to discuss your thoughts with one of their engineers and see how the products line up. After this, you'll need a designer to draw up a hull for you. In spite of the advances in yacht design software in recent years, none will address the unusual engineering issues, that WILL be encountered with this material. In other words, you'll need a real pro to work up a set of lines and proper scantlings for this stuff.

 

geez, I had forgotten about that post

anyway, these days I prefer aluminium.

 

Hello again!

I have been working on my velomobile project for what seems like forever. I wanted to have the first production model ready before Christmas and it looks like I will be able to make it just barely. The website and sales are next but that should be easy as I already have buyers lined up and I only want to make twelve to twenty four units a year max. I still intend to build the grancrete boat and as I saw some of the responses on the board were a little doubtful I thought I would clarify my original post. First of all I never said that the grancrete would have no frame or reinforcing matrix in the first post I said I would be using bamboo for this purpose. This idea isnt new as there have all ready been ferro cement boats built this way that are still in service. In fact there are already blue water sail boats built entirely from bamboo as well as bikes, surf boards, a few unique car body's, even my velomobiles . Certin bamboo by the way has a higher strength to weight ratio than steel.

Upon reflection and some reports of the incredible strength of grancrete with reinforcing mesh ( One excerpt from another fourm is as follows When used with a re-enforcing mesh Grancrete is nearly bullet proof. I have personally watched a video demonstration of a customer using two layers of re-enforcing mesh and Grancrete and it was able to stop a .45 caliber bullet. The bullet simply just bounced back leaving a slight dent in the Grancrete. I want it for my house) I have decided to go with the mesh idea as I want the option for one more feature on this boat. I will go into that in a second as people on this forum seem to be skeptical by nature ( by the way that is something I appreciate). First I would like you to see this website http://concretesubmarine.com/ this guy will build you a concrete submarine that has a crush depth of 900 meters! I intend to hire him as a consultant and as funds provide to engineer a boat that will be built able to sink beneath the waves to escape inclement weather or pirates as the case may be. It wouldn't need to go very deep at all lets say 30 feet or less to avoid problems with pressure and to keep the hull as lite as possible allowing a decent hull speed. I envision a large cat style boat that was a wave powered/diesel(veg oil) generator powered/ solar electric hybrid the two hulls would be able to fill with water and the center cockpit/ living area would be airtight. One question that seemed valid was about people purchasing these without being able to get loans or insurance. Well as world citizens we could look at countries outside of the US that have much friendlier views towards ferro builds like Australia at least for liability. I frankly would rather support companies that would support innovative building rather than closed minded American companies anyway. The loan wouldn't be a problem as well, unlike other boating companies who try to go the traditional route building offshore and then trying to sell through retailers adding costs all along the way this would be a cottage industry (built at home launched from the front porch to the ocean) build one boat at a time have a small down payment enough to cover materials ( materials on these boats could end up being really cheap say 10,000 to 20,000) and self finance. If someone could pay lets say 18,000 down on a total loan of 50,000 at 8% interest for a boat they could live on that could sink under the water in case of hurricane you think they would? Well I think some people would and of those at least lets say 10 a year would be willing to be governed by California law (only bringing cases to those courts and would be willing to sign a waiver calling sailing on these boats an extreme sport thereby limiting all liability of the manufacturer to zero). If I decided to sell to only two people a year I would still have more than enough to live on as I am lucky enough to think long term and have a very small nut to crack each year. The real treasure in this business would be to stay my own boss help people have affordable places to live. Help more people get into boating and possibly see the world. I would also see it as a positive to be able to pick my customers as opposed to trying to do this on a large scale and basically begging for an ever shrinking share of a market stuck in the dark ages. I would be able to, by example, move people to a better way of sailing using one hundred percent wave and solar power keeping diesel only for emergency's, people could travel for free without the shared expense of our children's lungs that current gas and diesel powered motors cost.

 

Water,

I would SERIOUSLY advice talking to an attorney about the the potential liability you are playing with here. Specifically find one that deals with Admiralty law not just a general practitioner. I don't think you are dealing with reality when it comed to the possible liability of being a boat builder and this could be a very expensive mistake... say everything you own plus everything you make over the next 10 years, minus some small stipend to live on lets call it 12,000 a year.

By the way, calling something an extreme sport has no bearing on FEDERAL maritime law, and to be honest as an attorney I don't really care what state law has to say on the issue unless it is better for me than the Federal. So even if Californial gives you some protection since you are entering the Maritime trade the Federal will almost always control.

Now you could get a buyer to sign a waiver of liability (almost worthless), you could get a choice of law clause in the event of a problem (also almost worthless in maritime issues), or you could accept that if something goes wrong you will be drug in front of a Federal Judge to argue your case. Now in Federal court a commercial enterprise has a duty to build a reasonably safe boat. I don't know anything about yours in particular but make sure you live up to this standard.

 

Now that makes some sense

I wasn't worried about selling the boats yet as that was going to be a final step after selling my bikes then building my boat for personal blue water usage ( If I didn't survive then the next step wouldn't have mattered). I appreciate your warnings greatly its nice to be a part of a forum where everyone looks out for each other. Let me ask you this do you believe if I sold the boat that I home built as an experimental boat as is with no warranties would I be open to the same liability issues? How about If I sold it as a partially assembled experimental kit that the customer put together like the ultra lite kit gyro copters and such? I honestly don't need to sell these for a living. Its just that there are so many people interested in world citizenship and the travel lifestyle in general. They would live the dream as it were if only they could afford it.

 

Water,

Honestly I would have to spend some time doing the research to give you a real answer. Most states have some form of assumed liability, meaning that if they knew it was an experamental boat then the buyer assumes at least some of the liability if it cracks up and they die. However this is not true for all states, and particularly may not be true for Federal Maritime Law. Since you could be sued under either set of laws, I would make very sure what your exposure is before selling anything.

My advise is to spend the couple of hundred bucks it would cost to have an attorney licensed in your state write an opinion letter for you about the potential liability, and then use that to get a corporate liability policy. Since you are only selling a few units it probably won't cost much, but if something happens without it, it could cost you everything.

 

Thanks for your time and all the advice!

I will take the time to find a good lawyer, my fiancee graduated SCU and passed the bar in CA but has no experience in these issues. Thanks once again for all the advice and I hope you have an exceptional holiday.

 

Grancrete ....

I would like to get intouch with Waterbeatsrock ..... I have been working on the Grancrete type material .... magphos .... for boats etc. Can we talk?

 

GAWDELPUS

but the lawyer is a good idea..................

 

some questions...

my experience with concrete is all masonry in nature. but i have done some light research into shotcrete as structural material, and one question immediately comes to mind.

the great strength of concrete is compression resistance; you can load the ever-loving hell out of it and it doesn't budge. concrete's greatest weakness is sheering force; as soon as you get any lateral force it crumbles. this is why you can only span any significant distance by using pre-stressed members - where they are already under self-contained compressive loads greater than the sheering load to be carried. one force counters the other.

how in the heck could you ever build a ship out of this stuff? presuming any type of V hull you're immediately going to be dealing with sheering force as the walls are pressed inwards from the central-line. it seems like you would need extensive ribbing and cross-bracing for days to keep the spans short enough that the thing doesn't just crack itself to pieces???

similarly... concrete does not deal with impact very well. a thick wall or column may be ok with moderate impact due to the sheer weight of the structure - and more often, the tens of thousands of tons of compression it's under - but the bow of a ship isn't going to benefit from either of those mechanics. it seems like one good blow and you're going to crack the hull... and once you crack it, water pressure would seriously become a problem.

???