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
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    congoriver Junior Member

    Don't shoot me, I'm trying several things at one time. Those who think "ridiculous", please don't read this thread.

    Here's the opportunity:

    -Fumbwa (Gnetum africanum) is a leaf-vegetable that is appreciated by tens of millions of people in Central Africa and even by the diaspora in Europe and America; it fetches high prices (up to US$50 per kg in the US and the EU...)

    -In Congo this crop is harvested in the forest (in the wild) in the Equateur Province (and elsewhere), and then shipped BY CARGO PLANE to the capital Kinshasa

    -The fact that people use airplanes means that if you could ship it by boat, you would probably make a bigger profit

    -Now the problem is that the leaves have to be shipped rapidly, because they spoil after about 3 to 5 days

    -Given that there are only large boats on the Congo River which take weeks to reach the capital, nobody's shipping this way

    -Airplanes only leave on Sunday's; leaves spoil after about 3 to 5 days; so at the end of the working week in Kinshasa (say Friday), the stock is often depleted or of bad quality; if we can arrive on Wednesday with a boat, we can contribute to building stock for Friday, Saturday and Sunday, and get a premium price

    -Prices for fumbwa: 350FC/kg if you buy wholesale in the interior (Equateur Province), and 1300FC/kg if you sell wholesale in Kinshasa, the capital. If you ship per airplane, you will pay 350-400 per kg.

    Here's an interesting study on the subject (it talks about the challenge of developing rapid river transport):

    -Etude de base de la filière fumbwa: http://www.fao.org/forestry/19958-0-0.pdf

    So here's the challenge: build a boat or a river transportation technology that can transport a considerable quantity of fumbwa, very fast, and that is more profitable than shipping by airplane.


    -transport approximately 5 tons downstream
    -over 500 km
    -in under 72 hours
    -fumbwa leaves are very bulky: approximately 150-200kg/m³
    -fuel price (gas): 600FC/l in Kinshasa, double up North
    -engine oil (SAE 40): 2500 FC/l

    My solution (don't laugh, plz): I made a sketch of something that might work, even though, again, I'm not a boat designer:

    -a small tug would speed up empty, from Kinshasa to the forests up North
    -arriving there, it would fill up a big strong polymer bag, shaped nicely, with the leaves
    -the full bag would be towed downstream
    -after unloading in Kinshasa, the empty tug will speed up North again with its empty bag folded up
    -these polymer bags exist, they're being used to haul fresh water, and both Dunlop and Goodyear developed them to transport oil during wars; one could build one very cheaply out of a "bache" material, which is sturdy; given the leaves' much lower bulk density, the bag would float mostly on top of the water

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  2. tinhorn
    Joined: Jan 2008
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    tinhorn Senior Member

    I think that's a helluva great idea, but I'm not a boat designer either. Your pic reminds me of the barges (up to six of them lashed together) that I'd see being pushed down the Columbia River.

    I used to buy Buchu leaves that grew only in southern Africa.
  3. bearflag
    Joined: May 2010
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    bearflag Inventor/Fabricator


    Better idea than the recycled aluminum boats.
  4. kach22i
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    kach22i Architect

    If you want river speed try a large hovercraft. The AP-188 is already in Africa, but operation with locals can be dicey as they do stupid things like putting gasoline into a Diesel engine and then lighting the craft on fire.

    Just One Example:

    High speed travel on a river filled with small craft and traffic congested is not a good idea. All aspects should be examined with care.

    Hovercraft Services From Targrin Resume In February
    Posted by Unissa Bangura on Jan 31, 2007, 00:28
  5. mark775

    mark775 Guest

    You've got it backwards - the boat needs speed when full, not empty.
  6. congoriver
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    congoriver Junior Member

    It needs speed both ways. Because going upstream empty needs to be done fast as well in order to play with the time-schedule of the cargo airplanes.
  7. kach22i
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    kach22i Architect

    I'm not sure to who or what you are commenting on Mark.

    Economics dictates that cargo craft run empty as little as possible. Two way commerce would seem to be essential. Perhaps this is a bigger problem than anything listed so far.
  8. bearflag
    Joined: May 2010
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    bearflag Inventor/Fabricator

    How about you guy just stick with ideas that are reasonably doable. With the money and engineering invested into a hovercraft as well as the additional fuel, you could have bought a whole fleet of boats, and been in operation for several years.

    Instead of worrying about going upstream so fast, why not just get more boats? While some are going downstream others are going up. The economy is never driving your boat with an empty cargo hold.

    And then find something that you can transport up river that people need that you can make a profit on?

    Like diesel, kerosene, and gasoline. I imagine the prices at the mouth of the river and upstream are far enough apart that you could make a profit.
  9. congoriver
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    congoriver Junior Member

    I've thought about that, but then I think you can never compete with the big boats out there. They go upstream very slow and travel only once in a while, but full of cargo.

    And the thing is: you're working on a time schedule. You want to go downstream fast with the fresh product, and upstream fast to get in time for a next round. You can never go upstream fast when you're full of cargo.

    The alternative is simply to have a series of boats, but that requires a larger initial investment.

    In the beginning you might make a relatively nice profit with the dedicated boat (the "bag + tug"), even though you're going upstream empty. With these profits you could buy more boats and transit to a system in which you go fast downstream, and slow upstream with cargo.
  10. RAraujo
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    RAraujo Senior Member - Naval Architect

    Question: how would you fill (and unfill) the bag with the leaves? It's easy to do it with a liquid but with leaves...

    And 500km in 72 hours is not such a high speed specially when going downstream. Are the 500km the real distance through the river?

    Once again I would suggest a small landing craft with the leaves stored in plastic boxes for easy loading/unloading.

  11. mark775

    mark775 Guest

    "Economics dictates that cargo craft run empty as little as possible"
    Yes, I thot he said that getting fresh product to market as quickly as possible was the objective. He further said that he was planning on dragging a bag downstream and hurrying back up to drag (slowly) another. Carry on.
  12. Ilan Voyager
    Joined: May 2004
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    Ilan Voyager Senior Member

    kach22i has a very good idea. But no need of a 2.5 millions bucks toy high speed toy like the AP1-88.

    The hovercraft is an excellent solution on rivers, little problems with depth of water, no need of harbor installations a beach or a ramp is enough. It uses common technology like plywood, fiberglass and it's easy to build. Car or small trucks engines can be used without modifications. It's widely used in Siberia in very hard conditions in summer on water and on ice in winter. On the Congo river ice is not a problem...
    A study made in Colombia showed the interest of hovercraft for the Magdalena River, but as the solution is not usual it's difficult to make accept by the locals.
    A speed of 30 knots is easy to obtain with a rather modest power. That puts a 500 km journey in less than 12 hours.
    It can be made pretty cheap: a 1 metric ton payload, 24 feet with a used Ford 2.3L Duratec engine of 145 HP derated to 110 HP for extra longevity costs between 6 to 10 thousands dollars, even less if you keep it very rustic.
    A very first idea: the UH-20C of Hovercraft http://www.hovercraft.com/content/index.php?main_page=index&cPath=35_55
    The plans cost 80 bucks and are worth to buy, even for simple information (I did it, very interesting, very simple).

    The hovercraft has to have paying payload on the 2 ways or it won't economically feasible. But a river "boat" able to make the journey is less that 12 hours at economical speed, at far better price than the plane, will be maybe of interest for the villages on the river for food, spare parts, medications etc.
    If the hovercraft is kept about 30 feet, under 200 HP, the technology is very basic with transmission by belts. The running cost is similar to a same payload small truck or van.

    Sorry the idea of the fast tug with a bag behind is not a good one. The drag of a such bag is horrendous, it's realization is not as simple as you think. And the idea to pack leaves in a hermetic bag under tropical sun does not appeal to me...The tug, a very specialized boat with marine engines, marine transmission, special propellers, is far more expensive than 5 light hovercrafts and has not use in the way back. You'll be surprised for the power needed and the consumption. It's the old naval engineer White Beard who speaks, hugh!
    For making 500 km in about 72 hours a simple boat 6 to 8 knots is largely enough, no need of special tricks.
  13. bearflag
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    bearflag Inventor/Fabricator

    The cost of fuel is also a considering factor in the developing world. I would think that a hovercraft having to travel several hundreds of miles each way (or more) wouldn't have the economy of a "go fast" tug, or have the towing ability of a big prop. I'd bet that an old airplane is probably more economical. Which is probably why the people selling it now are using them.
  14. uncookedlentil
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    uncookedlentil Junior Member

    This might take a little more development but if it can be pulled off......:)


    * 26 June 2004 by Brian Richards, Préverenges, Switzerland
    * Magazine issue 2453. Subscribe and save

    The interview with Hokan Colting, builder of up-to-date dirigibles, reminded me that it is now many years since articles about a renaissance of airships began to appear (22 May, p 44). We have read that for many applications where low speeds could be acceptable, dirigibles constructed using today's technologies would bring significant advantages over conventional aircraft or ground vehicles. These advantages would mainly be environmental: low fuel consumption, low pollution, low noise and low demand on raw materials.

    In addition, simplified take-off and landing infrastructures, and remote control - which could be made to operate with wide safety margins - would probably bring cost-advantages too.

    Modern dirigibles are said to be especially attractive for transporting bulky objects such as long girders, containers or large prefabricated elements. So it was a little disappointing that the interview made no mention of freight transport. The applications quoted by Colting mostly utilise the high-altitude performance of his airships. I would be interested to know whether the possibility of low-cost, environmentally friendly freight transport is still an aim in the development of modern dirigibles.

  15. bearflag
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    bearflag Inventor/Fabricator

    Dirigibles are great.

    Alas... they also require much more capital investment, and they need a certain economy of scale to make them worthwhile.

    There is almost no upper limit to their size though. Buckminster Fuller proved that.

    I fully support anyone who is willing and able to get a dirigible business up and running. Hell, if they were properly financed and had a good team, I might be willing to work for free even for a few years on such an endeavor, for a piece of the pie.

    But.... again, we are in dreamland.

    I think again the first idea is the winner. Or some modification of it.

    Your cargo is pretty lightweight. But potentially voluminous. You might even con sider a "very long" catamaran type motor boat.

    Something with very fine hulls, and a large deck area that you can load up with bags or crates.

    Without towing something, and since you arent' weighted down, you could easily do much faster speeds than a similarly configured monohull. And you could even make the thing in the jungle out of wood.

    Basically its the same idea as the hovercraft, except without the enormous expenditure in energy to float the thing on a cushion of air.

    Make say a 90 or 120 foot cat with a large flat deck, and some beefy multi hundred horsepower engines, and youd be in business.
    Last edited: Jul 15, 2010
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