Hull design question, efficiency from a delta pad?

Discussion in 'Boat Design' started by Tinklespout, Dec 26, 2013.

  1. Tinklespout
    Joined: Oct 2012
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    Location: Fl

    Tinklespout Junior Member

    Hi y'all, it's been a while.
    Still no Pangas found but I have a question for you geniuses! I'm dead serious about the folks here being experts.
    I ran across a 1989 200 DE Stratos, 20 feet long, weighs 2300 pounds, 10 degree deadrise at the transom and most importantly to me; it has a 10 to 12 inch wide flat running almost up to the bow. It's a sport fisher as opposed to one of their bass boats.
    Would the flat make this hull similar to the Panga and provide improvement to the gas mileage when planing?
    Also, is there a website that gives info on hull designs/gas mileage, etc. boattest.com had nothing.
    The boat has a 1989 yamaha 200hp 2 stroke.
    Any info would help, I can't find much at all on this boat.
    Kim
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Where are you fishing, and how fast do you need to go ? Scooting around protected waters or going offshore ? Doesn't seem suited to the latter. Anyways, 200hp outboard of that type has ouch factor at the fuel pump, built-in.
     
  3. Tinklespout
    Joined: Oct 2012
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    Tinklespout Junior Member

    Mostly in protected water. What do you think this setup will get?
    Kim
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Get, as in fuel used for distance travelled ? I wouldn't count on much better than 2.5 nmpg.
     
  5. Tinklespout
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    Tinklespout Junior Member

    Even with the delta pad hull?
    Thanks
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Planks, pads etc may help, but 2300 lbs is not that light, and carburetted 200 hp outboards are thirsty, if it gets 3 nmpg it would be a very good result.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

  8. Tinklespout
    Joined: Oct 2012
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    Tinklespout Junior Member

    Thanks for your help. Wish I didn't have to be so hung up on fuel economy but I have to be honest with myself, I won't use it if it costs too much to run.
     
  9. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    A four stroke 200 HP engine in good tune will use about 14 GPH. If you know the top speed of the boat, it is a simple division. For economy speed, you could make a lot of complicated calculations that are not better than an approximation. Otherwise, you can test the boat at several speeds until you find the sweet spot.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    There is no way a 200 hp 4 stroke will use 14 gph unless at or near WOT, fuel consumption will roughly double on virtually any engine between 3/4 of max rpm and flat out, speed does not double though. Even finding the sweet spot, it will still have a bitter after-taste at the fuel bowser.
     
  11. gonzo
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    gonzo Senior Member

    An engine will consume about 14 GPH to produce 200 HP. If it is rated at 200 HP that will obviously be WOT. That will be the top speed. What is your disagreement with my post?
     

  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    The "top speed" of the boat is an open question, he sure as hell won't be running at peak revs all the time, for practical purposes the only fuel figure of interest is what the optimal cruise speed delivers. I can guarantee the maximum speed he can reach with this motor, divided by the gallons per hour being used at that speed, will be well short of that optimum.
     
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