A better idea for Congo - a speedy tug and a plastic bag

Discussion in 'Boat Design' started by congoriver, Jul 14, 2010.

  1. congoriver
    Joined: Jun 2007
    Posts: 46
    Likes: 1, Points: 0, Legacy Rep: 23
    Location: Kinshasa

    congoriver Junior Member

    Would two 25hp Yamaha outboard engines be sufficient? We have those. We could test them on a catamaran.

    I'll have to check some prices on epoxy, and start working on a design.
     
  2. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    Touché
     
  3. congoriver
    Joined: Jun 2007
    Posts: 46
    Likes: 1, Points: 0, Legacy Rep: 23
    Location: Kinshasa

    congoriver Junior Member

  4. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    This is Carvel planked boats.... not what any of us are talking about. many many many catamarans are made form wood.

    Just makes something like this.

    [​IMG]

    The thread you sent me looks more like a "monohull vs. multihull" thread. Which is stupid. Both have their advantages and disadvantages, neither of which are the normal garbage espoused by either camp.

    One of the main things peopel say about catamarans is they can't carry any weight.... and that is about the dumbest thing ever said. There are hundreds/thousands of HUGE catamarans and other multihullboats the size of GIGANTIC passenger ferries, high speed barges, and military frigates.

    All things being equal.... a multihull "should" have less wetted skin friction than a similar monohull because for the same displacement it draws less draft.

    All you need to worry about is just to make 2 really long pontoons and build a platform to hold them together. Since you have no mast, the usual anti-multihull stress arguments are for the most part meaningless.


    Eitherway, monohull freight canoe with engine, or multihull freight canoes with a platform between them with an engine... Your main concerns are to maximize your buoyancy, minimize your draft, and maximise your hullspeed by minimizing your hull(s) beam to length ratio. Multihulls usually win on all these things, which is why they tend to be preferred for high speed applications.

    Alternately, for the "same internal volume" monohulls are hard to beat, just you will have a less stable platform, most likely be a bit slower.
    Multihulls increased stability allows you to stack stuff on top of it almost irregardless of geometry, as long as you have the buoyancy designed for it.
     
  5. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    You Are Over Thinking This

    Skin on frame boats are.... great.... for recreational use.... but also prone to puncture. I wouldn 't use them for freight applications or anything in open water. Would be unfortunate to lose a whole load of goods and your boat.


    Really ignore whatever other people were saying about wooden boats. Wood is a great material. Its cheap, its easy to work with, its very strong, its light.

    Melting rubber to reinforce a fabric skin sounds like a disaster waiting to happen without a more serious industrial complex.
     
  6. hoytedow
    Joined: Sep 2009
    Posts: 5,596
    Likes: 253, Points: 93, Legacy Rep: 2489
    Location: North of Cuba

    hoytedow Wood Butcher

    Congo is rich in natural(red) rubber. Why not use that?
     
  7. congoriver
    Joined: Jun 2007
    Posts: 46
    Likes: 1, Points: 0, Legacy Rep: 23
    Location: Kinshasa

    congoriver Junior Member

    I'd just be glueing it, though.

    [I'm reading your entire posts, so plz allow me some time to digest. Just wanted to clarify that quick detail on the rubber.]
     
  8. SKot
    Joined: Jul 2010
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Poland

    SKot S Kot

    I have probably great idea for you
    Few words theory first
    There are two way of boat swimming: displacement mode and planning mode
    Displacement vessels are swimming slow but with good economic efficiency
    Planning boats swimming quick but expensive
    I have third way for you
    Hydrofoil is the Best way for most efficiency cargo.
    I have won first award with my hydrofoil idea in design competition few months ago.
    You can see my hydrofoil here. http://www.kulinski.gdanskmarinecenter.com/k_admin/userfiles/Image/USTKAknockaut.jpg
    This is passenger hydrofoil, hydrofoil for you will be another one, but idea is the same.
    In few words
    If you fly by hydrofoil you have more less 10 times less drag than planning boat with the same Speed and size
    Drag are increasing to the Power of 2, demand for engine power are increasing to the power of 3.
    Solution of this problem is flying as slow as possible.
    Economic efficiency is absolutely incredible with this mode.
    We have one principle in aviation: cruising Speed is more less double Take off Speed.
    If we will have Take off Speed = displacement Speed, We will Fly with double displacement Speer.
    We will Fly 2 Times faster than displacement vessel in this reason, with the same length with less Power, with less drag,
    We will fly 2 times faster than displacement boat with much less fuel consumption.
    Wight of Take of my hydrofoil is 13 t, cruising Speed 20 kts
    Demand for Power for flight about 30 HP. For take of more of course, but for flight 30 HP only.
    If you are interesting with my idea, write me for priv I can calculate exactly economy of cargo hydrofoil for you. This is probably most efficient way for river cargo all over the world.
    Idea with Tug is not best idea. Wetted surface of your bag is too big and has to big drag.
    Your leafs must fly. Big wetted surface = big drag, big drag = big power and fuel consumption
     
  9. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    I agree.. but....

    It is most likely much more expensive? Perhaps not amortized over time, but keep in mind he is in an undeveloped country, will most likely have to do construction locally, will not have access to high end machining tools, or materials (such as readily available epoxy or glass).

    Financing operations in this part of the world is even harder, as almost anyone with the means is hopelessly corrupt. Or even shipping materials from abroad, the officials might rob you or require massive bribes to release your merchandise.

    If you could design a power-foiler with the other specifications and using mostly indigenous type materials (for instance readily available wood or steel (aluminum work seems a bit much based on previous posts), automobile engines, etc etc. It would certainly be an impressive feat.

    :)

    Its a challenge I suppose.
     
  10. SKot
    Joined: Jul 2010
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Poland

    SKot S Kot

    Bearflag, You right, but I’m living in country where lots of people are doing something from nothing.
    My favorite method of production is CNC laser cutting metal and welding.
    I understand restriction of African market.
    Idea is not for African market only.
    You can build beautiful hydrofoil yacht (this is almost impossible without CNC machines and modern materials) or simple workboat f.e. punt, pirogue etc. and adds wings.
    Most important thing is design and calculation.
    This should be a skin boat in my opinion with canvas painted shell, as simple as is possible.
    Wings are one difficult part, must be a metal welded. We need simple plasma cutter.
     
  11. sharpii2
    Joined: May 2004
    Posts: 1,915
    Likes: 118, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    I would propose a 21 m catamaran with about a 6 m beam. It would have an open cabin structure that is air conditioned. There is where the leaves would be stored. The air conditioning is to discourage leaf rot on the way down river and encourage paying passengers up river. It would be expected to go about 15 kts, down river at least. If it could do that, it could reach is destination in around twenty to thirty hours, give or take, depending on river conditions. It would travel up river with full fuel tanks and travel down river with tanks half empty. This will be to take advantage of the lower fuel costs down river. It's fuel consumption would be about: 10 hp/ton * 15 tons/12 hp/gal * 60 hr

    or about 750 gal or 2660 L

    Since the payload will gross about $22727 USD, this operation should have little trouble making money.

    I suggest starting out with one boat and later going to a fleet of three. This way you have one going up river, one going down river, and one being serviced.

    Whether the boat and engine can be built at around 7.8 mt, I have no idea.
     
  12. bearflag
    Joined: May 2010
    Posts: 227
    Likes: 17, Points: 0, Legacy Rep: 195
    Location: Thousand Oaks, California

    bearflag Inventor/Fabricator

    ::thumbsup::

    I concur in re: dimensionality.

    I wouldn't waste too much effort building the "deck house" though. I'd just basically build a simple tunnel structure from one hull to the other and put plastic or a tarp over it. No need to add weight or excess structure.
     
  13. congoriver
    Joined: Jun 2007
    Posts: 46
    Likes: 1, Points: 0, Legacy Rep: 23
    Location: Kinshasa

    congoriver Junior Member

    A 21 meter catamaran would look something like this. We'd just put the bags of leaves on there and cover them with a bache when it rains. When not raining, we can leave the cover off.

    If this is made out of wood (stich & glue or cold-molding or what have you), and carries 5 tons, how much HP should the engine be?
     

    Attached Files:

  14. pedalingbiped
    Joined: Jun 2010
    Posts: 22
    Likes: 2, Points: 0, Legacy Rep: 33
    Location: Seattle

    pedalingbiped Junior Member

    Hydrofoil is not the way to go. You would have too much experiments to perform to get the right one. This is the best book on basics.
    http://www.amazon.com/Hydrofoils-De...=sr_1_2?ie=UTF8&s=books&qid=1279604118&sr=8-2

    I bought it after seeing his sailboard hydrofoil on youtube.

    The picture of scot is a surface piercing foil. The Russians used that method for river boats.
    The US Navy went with submerged foils which are faster but you don't want to hit a bump with them.

    A pontoon boat should be easy to build with what's at hand.

    Here's a big one.
    http://www.panoramio.com/photo/4034467
     

  15. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    You can build beautiful hydrofoil yacht (this is almost impossible without CNC machines and modern materials) or simple workboat f.e. punt, pirogue etc. and adds wings.

    Aircraft props are still easily made from wood , and still being done after 100 years.

    The shape of a submerged foil is really simple compared to even the most basic puddle jumper prop.

    FF
     
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.