Ok everyone, it's that time of the year again: time to talk about concrete

Discussion in 'Materials' started by dsigned, Sep 21, 2017.

  1. Rumars
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    Rumars Senior Member

    May I ask what you are trying to achieve with this test panels? Just seeing how low you can get the weight? Or can you actually test them for other properties?

    If you really want to build a small boat in ferro and want something else than a canoe I recommend following aproach:
    1. Buy Jay Benford plans for his 12' keelboat. Benford Design Group http://www.benford.us/index.html?scp/ They are 60$ and the smallest FC boat I know of outside canoes.
    2. Buy or borrow Jay Benfords book about FC construction.
    3. Build a really sturdy strip plank male mold out of common lumber and fair it to perfection.
    4.Reverse engineer the boats structure.
    5. Invent some cement mixtures that are lighter than the original one while keeping the strength.
    6. Replace armature with something else while keeping the strength.
    7. Plaster test panels on said mold over armature. The original boat had 1/4" skin thickness and mirror finish. That's your benchmark.
    8. Test panels to destruction.
    9. When you are satisfied plaster a complete boat.
    10. Test boat to destruction, then repeat step 9.

    Microspheres (glass or phenolic) you can get for example from the epoxy vendors, they are used as fillers. Google everything and buy online.
     
  2. dsigned
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    dsigned O.R.C. Hunter

    The condescension and bad (or mundane to the point of headache) advice continues.

    "Trying" to achieve...sigh...

    Right now I'm primarily trying to learn about the mixes that I have available to me cheaply. How much water they take, what kind of workability I can expect, how they cure, how different things affect the color, what kind of porosity I'm looking at.

    As far as destructive testing, I can and may rig up a legitimate flexural test, but I think most of the properties are going to be qualitatively apparent. The weight is actually an interesting one, as I mentioned above. I forgot where the MK II was, but I think it was something like 80 ish lbs per cu ft. Not bouyant, but way lighter than normal concrete (even the MKI panel). Part of the reason that I'm not too concerned with the quantitative testing just yet is that I haven't added any pozzolans or water reducers/superplasticizers to the mix, and I haven't really done anything with the curing (although I may use some sort of set accelerator: 28 days is a friggin lifetime). Plus, the mix kind of is what it is. I'll make it as good as I can, and see if the result is good enough to sail around on. If it's not, then I might go back and evaluate where I can improve (which I expect there will be many areas, even without focusing on destructive testing). I'm not doing this for a project: there's no old codger evaluating whether I did the proper 12 test cubes for destructive compression testing.

    1. There is no good reason to go with a 45+ year old keelboat design. Other than the fact that it's small and that someone else made one out of ferro 45 years ago, it doesn't have much going for it. There are a million other boats I'd rather build that would be faster, easier to build, easier to rig, and easier to transport. Not to mention that I could potentially find and make a female mold from...
    2. Maybe? I'll ask the canoe engineer if he recommends it, but I'm guessing there will be enough disanalogies that it's not going to contain much that is directly applicable that I don't already know (or won't learn along the way). Especially since I'm not actually working with ferrocement, and the information contained therein likely hasn't been updated in decades.
    3. No, there is no reason to do this when I have closed cell styrene on hand. It's slower, more expensive, harder to work with and of dubious benefit for my purposes.
    4. Again, since the boat offers no appeal other than having been built by someone else out of ferrocement 45 years ago, not likely.
    5. Thank you, Captain Obvious.
    6. It's a good thing you mentioned this, otherwise I might have forgotten that I had previously mentioned fiberglass and basalt meshes, and PVA fibers.
    7. I love how you mention thickness but not weight or strength.
    8. K thanks.
    9. Oh, this was another step I might have forgotten had you not pointed it out. I was actually posting here and doing all this work to build a structural mammalian feline. That's what I thought "cat" was short for.
    10. I'll probably just sail it around on a lake or something.
     
  3. Rumars
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    Rumars Senior Member

    Ok i'll stop giving unrequested advice. You obviosly have enough of an ideea about boat scantlings that having an actual boat designed by an actual NA as a base reference is unnecessary.
     
  4. dsigned
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    dsigned O.R.C. Hunter

    Test panel #2 is down to 780g after drying out. I seem to remember after working it out that it comes to something like 71lbs/cuft 9 or maybe 68?) which is pretty darn close to my target weight (or maybe more accurately, getting a lot closer). Anecdotally, the panel is really stiff, and feels almost hollow. Lots of efflourescence. I tried some of the stain, but didn't do any prep, and so got inconsistent absorption.

    The latest pour is with more ground glass, and with some of the superplasticizer I got years ago added. Not sure if it's still any good. It definitely didn't affect the mix as much as I thought it would (I couldn't say that there was a drastic difference). This is actually a refractory mix to make myself a little forge, so I won't be testing it.

    I spoke with a regional lightweight aggregate guy, who said he would give me a sample of fine aggregate (which is a 5 gal bucket). It's actually not that light, so I'm not sure how useful it will be for me, but it's free.

    Haven't heard from the concrete canoe advisor, so I'll need to send my prof a follow up email.
     
  5. DAVID HOE
    Joined: May 2018
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    Location: HONOLULU, HAWAII

    DAVID HOE New Member

    I would like to get in touch with O.R. Hunter (designed) the author of this thread via email ... David K. Hoe tocsvs@gmail.com ... I build wooden Chinese Junkboats ... light weight hulls are not an issue ... maintenance is the bigger issue ... concrete hulls would be immortal and relatively maintenance free .... thanks.
     
  6. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    You can click on his name and then send him a private message by 'starting a conservation'.
     
  7. dsigned
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    dsigned O.R.C. Hunter

    I did just that, thanks.
     
  8. dsigned
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    dsigned O.R.C. Hunter

    Since it apparently looks like I was just being a jerk and ignoring you, I'm just going to leave this note saying I did in fact email you.
     
  9. Mr. Diy
    Joined: Oct 2018
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    Mr. Diy Junior Member

    After going through half the pages in this thread and feeling a bit frustrated and burnt out, I jumped to the end to post my 2 cents worth. The problem as I see it is the high cost of 'proof of concept'. Even $20k is too much to roll the dice on.

    Anyhow a bit of background. About 7 years go I became an economic refugee in the Philippines. I couldn't afford to retire in Australia, as accommodation costs rose to 100% of the age pension about a decade ago - up from 50 % two decades back. Retirement here in my 3rd world bungalow is great, beyond ones wildest dreams compared to Australia, rent is about 15% of my monthly budget. Other middle class luxuries are dirt cheap here - HD cable TV and internet combined for only $60AUD per month. But to keep this lifestyle I have had to become a DIY'er on everything with a first world price tag - supermarket and department store imports that would easily break my budget.

    What potentially throws a spanner in my lifestyle is the current trade wars and a huge plunge in the AUD and rising inflation in the Philippines. What is worse being up s**t creek without a paddle? Being up s**t creek without a boat! It was getting the cold sweats on that scenario which fired me up to pose the question as to whether I could build a live aboard catamaran for peanuts, given my current and past DIY skills.

    I have had building experience decades ago like going to night class bricklaying school for 6 weeks and then taking on the restoration of a 1870s colonial mansion that I had moved from Ipswich to Brisbane in 9 pieces. It had 3 chimneys 2 back to back cedar and Italian marble and another chimney attached to the kitchen. Cost me a total of $26k to buy for removal and shifting cost, and a few more thousands for footings and some new bearers to replace rotten ones. The rest was 5 years of part-time work. Sold in the late 1970s for $107k now valued at about $4 million AUD according to the online value checkers - as Brisbane's urban sprawl caught up with the property.

    Winding forward to my retirement years in the Philippines, perhaps my DIY design and construction experience in swimming pool filtration might help. That started quite a few years ago when I happened to see a Toys-R-Us Intex brand pool on discount an 8 footer diameter with a ring float to keep the water in. Trouble was it came with no filtration system and the local pool shops cater for 20,000 gal pools not 600 gal pools. After 3 design improvement to my filters and an upgrade to another half priced bargain - this time a 10 footer 1000 gal, I got a DIY pool I and offsiders can live with. Not sure how to post a pic here but can later perhaps.

    The pic of last sand filter upgrade shows a bit of a rough clobber together of the PVC - a result of having sourced from different suppliers here ( out of stock is normal here!) and different internal diameters of T's , elbows etc. To buy a professional filter to do the same job would cost 20 times as much as mine. The great thing about DIY is that once you get started, you learn how to do everything you need to do step by step by trial and experiment. The first pool was wrecked by baby teeth cutting holes in the plastic float and not buying a rubber base to protect the very thin plastic liner on the bottom. Solved in the last upgrade with professional AL backed stick on flashing for holes and 1/4'' vehicle carpet rubber underlay. On the filters themselves the evolution was from making throw away silicone sealed filters from recycled second hand $2 each chlorine 40k plastic drums. The next upgrade was to find and use 'union patente' joins that could be reversed to achieve back flushing. The final upgrade seen in the pic eliminated that unnecessary backflushing labor, by using cheap $1 plastic ball valves. A new improvement would be a vibrating plate base under the filters to speed up the back flush process which at the moment requires a tap with a hammer to dislodge the brown crud inside. The filters buckets used changed from Chinese to Japanese origin, the later having much better sealing under pressure.
    Which bring me to the current thread and the need to get the DIY process started with an affordable 'proof of concept' that one can build on. Now my filtration idea came from a guy in the states who had a basic 5 gal bucket system he used to drain and recycle/filter the water collected in his pool liner over winter. That was the start every DIY wants - something that WORKS that can be improved on. Applying that idea to this thread by improving what already WORKS in el cheapo DIY catamaran design. So do a google search and have a look at this cat-fish II project.
    Oil Drum Art http://www.oildrumartnews.org/catamaran.htm

    There are thousands of other projects showing various drums in pontoon and house boats designs. The all have one BIG limitation in my mind, being limited to river and lakes but not good enough for a boat one would need for a bit of live aboard island skipping up the Queensland coast that one could run up on a beach when the water got too rough. The cat-fish II is a great project idea for a NGO type service organization to float as a third world project. But as one with my a**e in the third world and in need of a boat for peanuts, it's not one I'd feel comfortable on with great whites, tigers and hammerheads swimming around when becalmed off the Frazer Island coast. So it must have a motor, two for safety and get out through light surf. To kick start this thread a bit, we need to think about what came first the chicken or the egg. The answer is the egg shell! The chicken can make the egg without the shell and without the shell there would be no viable chickens incubated. Solving that same question for catamarans the quintessential problem is the beams! That's the question this thread needs to get cracking on! A cat is four beams, 2 lateral and 2 longitudinal. For a proof of concept lets start with strings of 13" dia plastic 40kg bucket (in the foreground of the pic above) as 'O' then a cross section showing the beams roughly drawn would be :

    O"O ===== O"O
    The buckets can be sealed with silicone and maybe also filled with expanding foam and lashed / zip tied to a test box beam for proof of concept. If it breaks then go back to the drawing board and rethink ones beam design. The stumbling block this thread it stuck on is conceiving of the hulls as the quintessential element when they are not, flotation for an 18 foot test cat can be had for as little as $3.00 x 40 with the zip ties and silicone - $120. So please, somebody ' beam me up please ' - start on the " first then the second ===== and I'll set my sons to scrounge for a couple of outboards to go from there - something that works!
     
  10. rwatson
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    rwatson Senior Member

    The first thing I find about DIY boats is - they are always more expensive in the end.

    It costs the owner time, it costs on resale, it will costs on performance, it costs on longevity and in the worst case - will costs on someone's life. A strong offshore wind or tide and a broken/inadequate boat/steering system is every sailor's nightmare.

    Of course, a "home made" boat is uninsurable, and therefore not able to use commercial marinas or facilities, although something small could be used off the beach alone. But you are on your own if you participate in an accident of any kind.

    Already you have encountered one unanswerable question - how big/strong the beams ? No-one can tell you. Its non-computable.

    You haven't even establish the flotation limits, alone the weight of each hull, or the mast/sail specs.

    If you need a boat - I really recommend you get a proper design and cost it out. Honestly, nothing is ever going to be easier or cheaper than a proper design.

    It's a hard pill to swallow, but I am sure a few others will also be able to verify the best approach as proper plans.
     
  11. SamSam
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    SamSam Senior Member

    The point of this thread is discussing cement/concrete as a viable boat building material, as posted in the title. I don't think it was about anything other than that.
     
  12. Mr. Diy
    Joined: Oct 2018
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    Mr. Diy Junior Member

    filterPic.jpg
    The O.P was more focused than that - specifically focused on the prospect of UHPC and GFRC production types and new materials newtech-glass and basalt fibre etc to help to lower costs to affordable levels and raise the quality to a level that enhanced resale value. The problem is two fold - there appears to be only one instance of these new types. A canoe. Reading between the lines Mrs O.P. will never give the green light for Mr. O.P to trail blaze with $20k of family funds and build the first boat - an instance of one of the new types. What I was suggesting is that a focus on the beams using the new production types might be had for peanuts, or the O.P 's beer /pocket money and Mrs O.P would be none the wiser.
     
  13. Mr. Diy
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    Mr. Diy Junior Member

    I understand what you are saying - sure, given a bank account big enough to 'complete' a design guru's masterpiece...that is the best option. But what about the great unwashed.... those who don't have sufficient funds to go any where near such projects. Is their life better stuck in digs, or on the street, with all the druggies, thieves and gang-bangers as neighbors than on a boat that floats them to where they want to be. For many DIYers... necessity is the master of invention and virtually any 'quality of life' can be had if only one could get where they want to be. In my mind it's not the 'comb that you beach', but the 'beach that you comb'.
    Another great benefit of DIY is ....learning from design mistakes. In the filter project I made big trouble for myself initially by thinking of the whole, as a jumble of parts that together form the whole, instead of sections built with parts/components. If the impeller in the pump gets jammed saves a ton of time removing the just the pump component because you have designed it to be so. Now this idea can be used in your boat design - think about those take-apart-boats designed to fit storage or vehicles that are available. Most professional designers don't think that way because the assume anybody with the $$$ to build their expensive creation can afford trailers, captains and crew or other expensive options.

    How many designers would think modular and come up with my current preference - where the length is optional ? Want a 16 ' take the fore and aft sections and two specifically designed box-unions, a 20' or 24' take some extra sections and box-unions. Because I'm thinking DIY along the lines of 'beams first' you need a box-union (AL or carbon fiber) open top and bottom to take apart the longitudinal beams and other sections- because the beams are fully enclosed so can't be attached in the manner of a take-apart-boat. Now that your got the idea of the box-union you can extend its function and shape to handle a flotation section that includes those cheap $3 barrels rather than simply lash or tie them to the longitudinal beams. Modifications and improvement can then focus on the parts in sections that need upgrading. Not only that you are slashing costs to the bone, carbon fibre/AL just where you need it and nowhere else, cheap throw away $3 flotation buckets for buoyancy, cheap but well designed FC beams. The materials that have performed best in FC tests are known already, a starting point for further improvement. When the major problems are sorted, the beach where one wants to be gets closer if one can truck one's stuff, and assemble and maintain one's boat DIY style there.
     
  14. rwatson
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    rwatson Senior Member

    "a design guru's masterpiece." - Nah. You have it all wrong. Just a cheap, good value, well thought out , hydrostatically planned, structurally sound basic craft. It will save you double what an unplanned build will cost. You don't get points for reverse snobbery in open water.

    "on a boat that floats them to where they want to be." - add on "safely, for you and your loved ones, without spending 6 hours assembling it on the beach, and able to be stored somewhere without incurring council attention."

    " When the major problems are sorted," Sorting problems is called Designing. You are never, ever going to be confident in the structural strength of a "bitzer" boat, and unless you can fly, drowning is the only other option to an expensive rescue mission or enforced wreckage recovery order from the local harbour authority.

    Even for free, you won't do IT cheaper even if you get all the junk for FREE.

    As you sit there in front of your computer, dreaming of warm, gentle tropical breezes on an azure blue sea, get that Tom Hanks video "Castaway" out, and watch the section where his homemade boat takes him out onto the open sea, unable to turn back to shore, and gradually fall apart.
     

  15. Mr. Diy
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    Mr. Diy Junior Member

    A few points 'reverse snobbery' - had to look that one up, not a term Australians of my generation would be familiar with. We used to think in classless terms - all being 'mates' but in reality, a few would turn out to be ***** and foul mouth you to put a girl off dating you. Aussies and Kiwis used to believe in 'have a go' , to improve their lot, irrespective of social or educational background rather than bludge on welfare handouts. Bludger is defined as " A person who avoids working, or doing their share of work, a loafer, a hanger-on, one who does not pull their weight". In the USA vets are almost twice as likely to be homeless than non-vets. People who follow the 'system' are sure to get screwed the world over! I was on a beach, age 12, about 70 miles from home when a mate of mine decided to hitch hike home during the night rather than camp on the beach all night and go surfing the following morning. The best lesson I ever learned, on that weekend- if 'nobody gives a **** whether you live or die' , then the buck stops with you! Doing something with one's life by getting off one's ***** has had both upsides for me personally like getting serious about passing exams at school. It has upsides for countries to, in terms of adult median wealth - Australia ($195,417 USD) is third behind Iceland ($444,999 USD) and Switzerland ($229,059 USD) in median wealth. The USA is 25th ($55,876 USD) just ahead of Greece ($54,665 USD). But the USA is third in the OEDC list of countries with income inequality, behind Mexico and Chile. So, I guess, your 'reverse snobs' are the boat bums who didn't work three miserable jobs to save enough money for a harbor authority approved 'designed boat'! If you see a DIYer drowning, he's probably had a wonderful life and is probably dying with a smile on his face. Everybody's luck runs out sooner or later. All your 'up the right channels' stuff is why I'm comfortable in the third world. There is a bridge near where I live, and on the railing of the bridge you'll find the words "God is love" beyond the railing up the creek, in the background, is hundreds of squatter shacks or bitzer homes as you might call them, made with bamboo and any piece of scrap junk they could get their hands on. When floods wash some away, the squatters get to and simply rebuild them. In a country, without Roe v Wade, people accept all manner of clandestine solutions to the problem of getting the necessities of life for a large youthful population, the rich simply look the other way, and the squatters and settlement dwellers find happiness in family life not the material luxuries of the affluent.
    Yes I've seen the Tom Hanks movie a few times - without the DIY raft he would not have been rescued by the passing cargo ship - it didn't fall apart completely. What fell apart was his old life, the girlfriend had moved on with hers thinking he was dead. The end of the movie is one of optimism - the shiela driving the truck. His initiative in taking back the fedEx parcel opened up the possibility of a new opportunity - a new relationship. Try some rose colored glasses when you catch the movie the next time.
     
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