Need advice on software for hull design(barge style)

Discussion in 'Software' started by chowdan, Jun 8, 2015.

  1. chowdan
    Joined: Jul 2008
    Posts: 91
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Hey everyone,

    I'm looking at building a barrel barge for a concept design of my barge.

    I originally was thinking about just using an old pontoon boat for the hull, however building a "house" like structure, or something similar on the top just doesn't seem like it will hold up long term.

    This has led me to look into different avenues that provide sufficent floating supporting, and stability overall. I have come across "barrel barges", and the concept behind them seem to be what I am looking for however maybe someone else has better recommendations.

    I'm looking for a software that I could use to design my barge, provide data points such as weight that will be carrying and seeing where flaws could lie, prior to sinking time, and money into this venture.

    The barge that I'm planning on building, will contain its own outboards, fuel tanks, and helm, however I want to be sure that it is stable as it will be a dual deck(atleast part of it). So the height will be roughly 10ish feet tall(from the interior floor) for sun bathing.

    The hull I was thinking would contain the barrels, which would be encased in either a fiberglass/plywood structure, or aluminium structure depending on my funds. The one thing I need to consider is how would I access these barrels if i need to replace them(something I plan on researching on the forums here in the next few days).

    Anyone have any tips/recommendations/positive or negative reviews on plastic barrel barges. Any downs or upsides? Other/better products to use instead?

    Also software to use? Free!Ship is what i was thinking i'd use, however i'm open to changing.
     
  2. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Is not easy finding software that calculates a float consisting of several barrels. I do not think, but I really do not know, that Freeship be able to.
    Search what's on the market, listen to the suggestions of the experts in this forum and, if you do not find the ideal solution for you, send me an email.
     
  3. chowdan
    Joined: Jul 2008
    Posts: 91
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Thanks for the response! Really appreciated! I from the minimal searching that i've done, most people do not recommend the plastic barge style boats, however I haven't had the time to dig into exactly why they aren't liked.

    Here is the design idea I was going to use as a model concept for my barge.

    I do think that having 2-3 pontoons would be far more effective in terms of navigating, less resistence, however I haven't had the time to look up concepts/designs on how they are made(DIY)

    [​IMG]
     
  4. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I see that you're serious about building your pontoon with plastic barrels therefore makes no sense that no one talks about whether the system is good or bad. What you need to do is try to build the best possible way and make calculations with greater accuracy.
     
  5. chowdan
    Joined: Jul 2008
    Posts: 91
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Thats an example of what I'm wanting to build, at least an idea in terms of structural design, that I am thinking. Hence why I'm open to suggestions currently :D

    Sure some say one ways better than another, but i guess it all comes down to personal preference.

    Cat versus mono, tri vrs cat, aluminium vrs wood, wood vrs fiber
     
  6. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 10, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    Why not a traditional barge where your cargo space or in this case living space is built right into the hull, at least for your lower level? You could still build in some buoyancy tanks or storage containers and so forth if that was your concern. I would imagine even built new a steel barge would be relatively inexpensive, at least the exterior hull. Used barges might be sketchy. Another idea might be a matched pair of worthless fibreglass or ferocement or steel hulls barge them together if you wanted a squarish platform to build on, and in.

    Another fun site:
    http://www.livingafloat.com/
     
  7. gonzo
    Joined: Aug 2002
    Posts: 14,551
    Likes: 681, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    It makes no sense to build and fill it with barrels. A proper hull will be lighter and cheaper and have more storage space. Ideally the heavier equipment will be installed low, where you plan on putting empty barrels.
     
  8. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 10, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    very well said
     
  9. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    This type of barges intended to have only enough floats to support its own weight and the weight that is on the deck, they don't need cargo spaces or for storing equipment, "hulls" are only empty watertight spaces. Of course, it is always good to put the weights as low as possible but in these barges as low as possible means on the deck.
    There are many types of barges that surely the OP already knows. I have the feeling, perhaps unfounded, that chowdan wants to do something similar to what is shown in the pictures and do not want to do what others would. Therefore, let us tips on how to do what he wants to do.
     
  10. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 10, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    The OP is looking for software, presumably to perform basic hydrostatic calculations.
    I think they could do the calculations by hand easily enough, or using MS Excel.
     
  11. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    We agree. This being so, I do not know why you agree with the statement: "It makes no sense to build and fill it with barrels", which is beside.
    On the other hand, I would be interested to know, an example or explanations on how to calculate the hydrostatic this type of barge with Excel. Thanks in advance.
     
  12. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 10, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    I would break up the raft and superstructure into its elements, and for each element I would calculate its mass, center of gravity (x,y,z). For the elements which will be immersed (perhaps just the barrels), I would also calculate the displaced volume and centre of buoyancy (x,y,z) as a function of change in immersion (z), change in heel (about xz plane), and change in trim (about zy plane).

    From this you should be able to calculate the following.
    1. The immersion below the design waterline for a given mass.
    2. The amount of trim about the design waterline for a given distribution of masses.
    3. The amount of heel about the design waterline for a given distribution of masses.
    4. The center of gravity.
    5. The centre of buoyancy.
    6. The mass or weight to change the immersion by 1 inch.
    7. The moment to change trim by 1 inch or 1 degree or however you wish.
    8. The moment to change heel by 1 inch or 1 degree or however you wish.

    It would be a little different than classic hydrostatic calculations when it comes to the modelling each cylinders from their geometry rather than using a table of offsets, but otherwise it would be pretty much the same. You could also do it in something like Solidworks I suppose. Iteratively move the waterplane until your centre of buoyancy is below the centre of mass normal to the waterplane. I would do it much quicker in MS Excel. It would be easier for me because my first job after high school was doing hydrostatic calculations by hand using a table of offsets and Simpson's Rule, before microcomputers and MS Excel was invented. So I have a better feel for what we are trying to accomplish.

    The dynamics would be a little more challenging. How it might behave in waves, or even something as simple as the period of pitch and roll. For small angles it would be fairly straight forward, but for larger angles there would be a lot of non-linearity and damping from the barrels. For that I would go old school and build a physical model. You would need the mass moments of inertia of your elements and calculate the total, and then model that with your physical model with just 2 or 3 masses.

    If anyone knows of some better software specific to barrel rafts, have at it. :)

    p.s. One thing that might be good about these barrel rafts is how they might dampen motion from waves. Not sure.
    I presume this is for a houseboat that would remain more or less in situ and wouldn't be moved around a lot.
     
  13. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    chowdan, technically no insurmountable problems to build the barge you want with empty barrels. Nor can be said that your barge, as float, is worse or better than other types. In my opinion, if you want to build that barge, keep in mind that plastic drums can be drilled more easily than other materials so please protect them properly and you must think of a system how to replace damaged barges. If you can not get this, you should think of another construction system.
     
  14. TANSL
    Joined: Sep 2011
    Posts: 6,219
    Likes: 297, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Jamie Kennedy, wat I was wondering, because it has aroused my curiosity is how to calculate the hydrostatic for that barge with Excel. You tell me what I already knew, even I know several applications that calculate everything. But if you really can calculate with Excel, the OP may like to know that not have to look any special software (Freeship, or whatever) but simply follow your method to Excel.
     

  15. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 10, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    Yes I think so. The only complicated thing, I think, would be the formula for the center of buoyancy and displaced volume of each barrel, as a function of 3 variables: the depth of immersion, angle of heel, angle of trim; and 5 parameters defining the location and xy orientation, which varies from barrel to barrel but is fixed once defined. The formula would be based on a fairly straightforward intersection of a plane and a cylinder, or whatever geometric shape the floats happened to be. That formula could be copied from cell to cell in MS excel for where the center of buoyancy and displace volume are calculated. From there they would be used to calculate the total displaced volume and centre of buoyancy and so forth. The tricky bit might be to iterate all that to find the static equilibrium, but as I recall, from what might be 36 years ago now, that is also pretty standard approximation and could be done in excel without too much fuss. Fun stuff. When I have time I might do an example, but I am way behind on some work. They period of roll and pitch is a little more complicated for large angles but for small angles would be straight forward I think. The response to wave action I will leave as an exercise for the students. ;-)
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.