Power needed for a 25m+ (82ft+) pirogue?

Discussion in 'Boat Design' started by Bioboat, Sep 18, 2008.

  1. Bioboat
    Joined: Sep 2008
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    Location: Europe

    Bioboat Junior Member

    Hi, sorry to bother you again with my wood gas boat plan, but I am currently looking into pirogues. Mind you, this is all very early stage.

    Okay, so I've asked around a bit, and going prices for very large pirogues in Congo are between $1500-3000.

    The high end price would get you a pirogue of 25 meters (82ft) or longer. Some of these boats are over 30 meters (98ft) long, last a lifetime and easily carry 60 people + cargo.

    Now I'm having trouble estimating the power you would need to get such a pirogue going smoothly.

    -I would look at a canoe with the following dimensions: 25 meters long x 1 meter wide x 1 meter high (82ft x 3.3ft x 3.3ft). - Such as the one seen in the picture. The bottom of the pirogue is a solid piece of wood around 20cm (0.65ft) thick.

    -It would carry 25 people with cargo (50 to 100kg each / 110-220lb) or 50 people without cargo.

    -It would cruise the Congo River.

    -It would use woodgas as a fuel, so we'd be looking at 30% lower power output.

    -It would be powered by 1 (or 2?) outboards.

    Anyone care to help me get the basics as to how I calculate the horsepower I'd need to get such a boat moving?

    Thx for any help!

    Attached Files:

  2. terhohalme
    Joined: Jun 2003
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    Location: Kotka, Finland

    terhohalme BEng Boat Technology

    Try 5 hp (petrol) per 1 tonne. This is normal for a displacement vessel. The weigth of the pirogue is about 4 ? tons and 50 people an other 4 tons. 40 hp petrol engine should be enough for 12 knots. So about 60 hp engine using woodgas.

    Just a guess...

  3. Chris Ostlind

    Chris Ostlind Previous Member

    39" x 82' ? Wow! That is skinny, dude. What kind of guys are driving these things that they stay up during use?

    Not doubting your numbers, just amazed regarding the realities of having 50 people on board such a narrow vessel.
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    FAST FRED Senior Member

    Try 5 hp (petrol) per 1 tonne. This is normal for a displacement vessel.

    About 3 hp per ton is all most hulls can handle without a huge wake.

    I'm talking h HP in the water , not from the engine assembler.

    With such a skinney boat 2 HP /ton should do for 8 to 10K.

    I too wonder how you will keep 50 land lubbers from capsizing such a vessel on climbing aboard .


  5. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    :D Easily driven boats. This kind of hull form can be driven about any (reasonable) speed one wants so the main criterions for the boat speed are stream speeds (with all variations of it) in the river to overcome plus the relative speed for advance safely.
    Don't know for sure about Kongo, but reckon up to 10kn stream?
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