Concrete Barge Design

Discussion in 'Boat Design' started by Daniel Veraguas, Sep 19, 2018.

  1. Daniel Veraguas
    Joined: Sep 2018
    Posts: 1
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    Location: Sint Maarten

    Daniel Veraguas New Member

    Hello everyone, I'm designing a concrete barge to become a floting bar/restaurant.
    The dementions will be 80'X40'. I would like the deck to be 5' from the waterline and the bottom and sides to be very strong. There will also be tanks, bulkheads, built from cement. Any help with design and displacement would be appreciated!
  2. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    First off, develop a SOR, stating all the requirements you can think of for the vessel.
    Then add up the weight of everything and everything including the hull and passengers.
    Post that up and I’m sure you’ll get valuable input.
  3. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Just a few random thoughts, in no particular order.

    Do you intend to build this barge on the beach in St Maarten, and then use her as a floating restaurant there when she is completed?
    Would she then be launched in traditional fashion, perhaps sliding on rollers into the sea?
    If yes, will she be moored inside the lagoon or outside? If outside, in the event of another hurricane will her 40' beam allow her to pass through the swing bridge into the lagoon?

    Re your dimensions of 80' x 40' - that is 3,200 sq ft of deck area which is pretty impressive. You will have ample stability, hence you should be able to add another deck or even two - two more full length decks will give you almost 9,600 sq ft of floor space (assuming a rectangular brick shape) - is this how much area you need for the restaurant?
    Re a freeboard of 5' - if the draft is say 3', then the hull depth is only 8' over 80' length giving a Length / Depth ratio of 10 which is pretty high really. Although a properly engineered steel framework for the additional deck(s) will help enormously in providing good longitudinal strength re bending (with a decent safety factor) , when calculating the midship section properties for strength purposes.

    Building a ferro-concrete (or any type of) floating 'box' this size will involve some pretty hefty scantlings - not only will you need to be worried about longitudinal strength (re maximum bending moments), but also about the twisting / torsional strength. Rather like trying to twist a matchbox - it is fairly rigid with the box inside the shell, but it can still twist.
    This will require a LOT of steel to be used as reinforcement for the concrete. This steel weight could perhaps be half (or even more) of the weight of steel required if you were to build the hull out of steel plate (this is a very rough assumption). Couple this with the requirement for a LOT of labour / manhours to do all the concrete work (as well as the cost of the concrete), and you might well find that a steel hull could prove to be cheaper to build in the long run, when compared to a ferro-concrete hull. .

    Say you have a steel hull - there will be no need to have a 80' x 40' box - this will have enormous drag when you are trying to manoeuvre it, and you will not need all that buoyancy. You could consider building a steel catamaran hull form instead. Add a bit of rocker at each end of the two hulls, and she will be much happier when you are trying to move her from A to B (eg in the event of a hurricane). For an 80' x 40' platform, for an initial iteration, the hulls could (for example) each be 15' wide, with a 10' space between them - you can modify this later, depending on how your weight calculations 'come out'.

    As CapnD says above, do a rough initial weight estimate - start off with the desired number of punters and crew on board (is the floor area sufficient?), the total weight of all the stores, supplies, water, diesel (if needed for generators if you do not have shore power).
    A hull weight estimate would be much easier to do with a steel hull compared to a ferro-concrete hull - work up a rough estimate for the weight of steel plate required. You probably don't want the thickness to be anywhere less than 1/4" / 6 mm for the initial calculation - calculate the total hull surface of the hull(s), and multiply by the thickness to get the volume, then multiply by density (typically 7,850 kg / cubic metre) to get a steel weight.
    Then be a bit pessimistic, and add on another 50% (for this initial estimate) to allow for hull framing (transverse and longitudinal) and bulkheads, to get a rough idea of steel weight.

    PS - another thought - if you are planning on only having one deck on an 80' x 40' barge, then it would be prudent to consider building a smaller barge, say 60' x 27' - with an extra deck above the same size as the main deck - you would then still have the required 3,200 sq ft (approximately)
    Last edited: Sep 20, 2018
  4. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    Good input, Bajansailor
    I’ve done quite a lot of concrete work, mostly heavy industrial structures, and my gut feeling was that concrete, with all the reinforcing necessary, would be quite a bit heavier and more expensive than to build a similar sized steel structure.
    Also an issue with concrete construction is that, like fiberglass, everything must be built first stoutly formed up (molded) strong enough to support the wet concrete and rebar, then stripped off after the concrete cures, (28 days) and often a large portion of that is thrown away, at considerable expense.
    Is there a compelling reason why you choose concrete as the material to build the barge from?
    How about purchasing an existing steel barge and building a superstructure on it?
    This could be done in any number of ways and combinations of materials, including wood, concrete and steel.
  5. JamesG123
    Joined: Mar 2015
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    Location: Columbus, GA

    JamesG123 Senior Member

    If you're going to try to operate a public business from this structure, your going to need to get approvals and permits. You are also going to have to carry insurance and not just insurance on the whatever you build, but also for the construction and general liability for it while open to the public. If you're going to get permits and insurance, you're going to need to hire a professional designer and contractors to do the build. No, consulting does not count.

    Even if you wiggle around any kind of legal requirements (Carribean...) , the insurance is still a good idea because hurricane or drunk idiot falls overboard and drowns, you're done otherwise. And I doubt anyone will touch something built by you and your mates under the guidance of "some guys on the internets".
    Ilan Voyager and rwatson like this.
  6. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Sint Marteen is a Dutch territory. So you have the stringent European and Dutch laws to respect, with inspectors, certifications and tutti quanti. It's not a third world country...But happily the Dutch have plenty of experience of barges, floating houses, floating restaurants and discos, and are masters of naval building in the very wide meaning of the word.
    The first thing is to consult a specialized dutch company, your project will be a piece of cake for them. And you¡ll be sure to get the certifications, authorizations, permits and insurances.
    As too old retired Naval Engineer, I can say that steel will be the cheapest and simplest technique for this kind of project, it can be done outside, no need of costly molds, no special mixes nor 28 days humid curing and months of drying. Steel does not need very highly qualified people for a simple project.
    The cost of protection and painting will be the same as for concrete.
    You have plenty of primed (pre-painted with a weldable primary) plates of steel for naval building at good prices, so no big sand blaster needed. And it's pretty easy to transport by ship. It can even be precut as kit, shipped and simply assembled and welded at Sint Marteen. Think of that.
    Steel has also the advantage, when making simple shapes, of needing a few tools, a few MIG welders (rather cheap now) using carbon dioxide gas, and its easy to modify and repair. Other last advantage the brackets for the super structure are simply in stainless steel welded with SS 309 apport metal on the carbon steel hull and deck, even a a inverter stick welder can do nicely the job. Besides the structural calculations will be a breeze to make.
    Do not have illusions about the total cost whatever the material, that won't be dirt cheap. A structure, furthermore a floating one in hurricane country for public use will be rather expensive.
    JamesG123 and rwatson like this.
  7. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Hi Daniel, are you still with us? I hope we haven't put you off too much from your project.
    The general consensus above is that ferro-cement is not a wise choice of material - a 'proper' steel hull is probably the best way to go, for what you have in mind (and aluminium would probably be better, re maintenance, but a lot more expensive).
    However the stark reality of building this floating restaurant is that it is always going to be relatively complex and expensive, even if you try to build it on a beach somewhere and not worry about any rules or regulations.
    And that would be rather fool hardy really.
    Are you at liberty to disclose what sort of budget you have available for this project?
  8. Asante
    Joined: Jul 2019
    Posts: 4
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    Location: Texas

    Asante New Member

    Hello Daniel
    Contrary to much of what I have seen in the comments back to you regarding your 40’x80’ Restaurant Barge, I believe you should consider building and redesigning to a more stable shape with UHPC - Ultra High Performance Concrete.

    First of all this nano-ceramic Cement can be formulated to be as strong as steel, but does not corrode, not affected by UV light, and is waterproof in and of itself.
    It’s vastly superior strength and performance would be an ideal choice for your project eliminating inherent problems with metal, wood and fiberglass.

    We have build 3 typical shaped barges over 100 meters still in use in Indonesia today.

    Your project however I see could be very simple....once determined how it is to be used, the motion and use would determine the optimal design form.
    A UHPC formula with a low specific gravity that floats in water would be ideal and eliminate the problem of sinking and at the same time may be able to be cast in a fabric form right in the water.
    Liquid UHPC will not segregate in water and the fabric form would be the ideal economical solution. an optimal shaped floating raft and put your living-entertaining structure and infrastructure on the top of it. Then...Have it towed where you want it to stay.

    Designing it to endure a hurricane would be probably, but evacuated during the storm and return again when safe.
    Having an internal drive system would be an additional cost and would of course alter the design if it is the vessel is to be moving.
    Good luck...!
  9. tz3dcom
    Joined: Jul 2006
    Posts: 115
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    Location: China

    tz3dcom 3D

    Hello Asante,

    I am current working with a water villas developer , We are thinking about the concrete barge hull . Do you have more detail info about your UHPC barges project for me to study ? Gould you make a suggestion (estimate) for cost to building a 17M* 7M UHPC barges hull ?( exclude the mould cost)

    Many thanks for your info !
  10. Asante
    Joined: Jul 2019
    Posts: 4
    Likes: 0, Points: 1
    Location: Texas

    Asante New Member

    Yes! Of course I would be glad to help.
    Please email me direct at or call at 774-208-1766...Houston, Texas area, to discuss this in detail, I would need a lot more questions answered.
    First, I might suggest you consider a UHPC formula that is buoyant in water and therefore unsinkable in and of itself. Then, we may go about payload and functional dynamics, then costs.

    Remember...quality is free ! What costs is doing it over the second time because you did not do it right the first time.

    Best regards and looking forward to discussing this further...

  11. DocScience
    Joined: Apr 2010
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    Location: Sydney, Nova Scotia, Canada

    DocScience Wishful builder

    I found this topic very interesting .... I would like to read more about this ....
    Can someone briefly tell me or preferably give me a link that explains what is
    ""UHPC formula that is buoyant in water and therefore unsinkable in and of itself""
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