boat designing help!! PLEASE!

Discussion in 'Boat Design' started by ber1023, May 29, 2008.

  1. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    hi, i am from bermuda and here we race small outboard engines. the fastest hulls are displacement hulls and some reach almost 20mph with a olld 5hp engine with 2 adults in the boat. the fastest boats are all in the 25ft area and long and skinny. the bows are very sharp and tapper off to a flat bottom. can anyone help me design a boat with measurements and stuff to have the fastest? using hydrodynamics and hightech software. most boat here have been made using trial and error and knowing wat seems to work. i want to be the fastest so im looking for someone to design one for me as a favor. im 15yrs old

    the pictures are examples of some boats that are fast

    thanks
     

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  2. DanishBagger
    Joined: Feb 2006
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    Location: Denmark

    DanishBagger Never Again

    I can't help you (I don't have those kind of skills), but those thingies look like quite a lot of fun. I'd love to try one of them in some big waves :D
     
  3. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    yes we go around bermuda and the south side is open ocean

    42 mile race the fastest time has been 2hr 16mins
     
  4. CTMD
    Joined: Dec 2007
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    Location: Melbourne, Aus

    CTMD Naval Architect

    Are there material restrictions? What would you build the boat out of?

    Ok here is the deal, I like to see kids doing this sort of thing and I'm willing to help you out for free, however, this is your project and you're going to do all the work. I'll provide advice when and if needed and help you to assess the options you come up with. But I won't design the boat for you, a project like this is about learning.

    If you're interested drop me an email to chris (at) ctmd (dot) com.au
     
  5. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    i think nidacore structural foam and 1 layer of glass. im aiming for light weight. i have built a boat before and my dad is a boat fanatic (he has 10 boats and about 60 outboard engines and restors them)

    i know basically wat hulls work and how to make it (stitch and glue) but if i got somthing professionaly designed and put on hyrdro dynamic software then i think i could have a advantage. i have the money to make the boat im just looking to biuld the fastest boat and not build one and find out its not the best out there racing.

    thanks hope you understand what im trying to say
     
  6. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    How much are you allowed to modify the motor, I can see more improvements in the motor than the hull, they seem to have already sorted that out. Looks like a lot of fun.
     
  7. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Holding the long motor handle looks like bother. I would go for some kind of inside wheel and throttle. The hulls look good in the water, but I think you could make them more aerodydynamic - for better airflow.

    I think i read that at 10mph, bikes use 50% of the energy pushing air aside, so at 15+ mph, getting a nice smooth airflow ought to help a lot. You could go for smooth edges on the deck, some sort of curved windscreen if not a complete cockpit roof ( like a fighter jet)


    Do the boats capsize ever - like a canoe?

    Are you allowed to have some sort of outrigger ?
     
  8. CTMD
    Joined: Dec 2007
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    Location: Melbourne, Aus

    CTMD Naval Architect

    I was kept awake last night thinking about this design...........

    Initial thoughts.

    1. If an outrigger is allowed, fit one, you'll be able to make your main hull far more efficient.

    2. cut down your aero drag by laying down (think formula 1)

    3. Get the outboard off the transom and move both yourself and the outboard forward. The outboard can be "built in" and steerage provided by a steering system stolen off a surf ski. Moving the weight forward will enable you to built a much more efficient transom shape think canoe or ski.

    4. You need to analyse the advantages of a long boat. Calculate an approximate weight per length and work out where you start getting diminishing returns by going for a longer bow.

    5. Double check that a really small planing hull wouldn't be better.

    6. You say your dad has a lot of outboards and a lot of knowledge, could any of the outboards be modified to swing a bigger more efficient prop? Would this be legal.

    Step one in this design like any other is to work out weights. Start with your weight, the passenger's weight and the outboard weight. These can all be measured and won't change, after that you'll have to start guessing and calculating.
     
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  9. tom28571
    Joined: Dec 2001
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    Location: Oriental, NC

    tom28571 Senior Member

    I think some of your ideas are on target. The short planing hull idea is not probably useful since at least half of the course is in the open ocean. There will be waves, sometimes small, sometimes larger ones with swell. Outriggers should help if they are allowed.

    The photos show that some real thought has gone into developing the best boats. Long and skinny but with what looks like a planing stern for smooth water and the bow out for lowering wetted surface in these same conditions. The wider stern also gives much needed transverse stability. Moving weight forward might help in the offshore leg but would be slower when conditions allow planing. The winning hull has to be able to adapt to widely varying conditions on the course.

    I might look at what can be done to make the boat more efficient in different conditions as the course moves from smooth to rough. Wind must have a bad effect on steering in cross winds. A forward air rudder might help to avoid over steering the motor for course correction. When the bow is down in the water, steering must be difficult at best since the boats appear to have excess tracking at that time. The forward air rudder or a small bow bow rudder might help then. The ability to move crew fore and aft looks like a good idea.

    These ideas are free and may be worth almost as much.
     
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  10. kengrome
    Joined: Jul 2006
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    Location: Gulf Coast USA

    kengrome Senior Member

    I think the problem here is we do not know the 'rules' of the competition ... and we cannot suggest the best path to take until we do.

    For example, if outriggers are allowed the best way to go is probably to maximize the hull's waterline length and minimize waterline beam. Then the outriggers can come into play only as needed, and with the boat moving at a decent speed they may not be needed at all except at rest.

    But hey, if outriggers are banned then there goes that solution!
     
  11. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    hi guys, the motor can be fully modifyed but it would be in a different class, i have a small planing boat that goes 22.7mph with a 6hp on GPS and it wouldnt be as fast as the long hull because you need to ppl in the boat, displacement is the best, adding a ourigger would make it a multihull which i dont want. it can tip easy but even in the ocean it can be managed fine will people concentrating on balance

    i need a hull deisgn to be made using hydrodynamics

    the engines are british seagulls or a selva sport 6 hp

    http://www.saving-old-seagulls.co.uk/ , http://www.britishseagullparts.com/ , http://www.britishseagull.co.uk/

    ... some websites with some info
     
  12. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    also the engine weights,, idk 60lbs and passenger and me would proberly be about 300lbs
     
  13. kengrome
    Joined: Jul 2006
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    kengrome Senior Member

    First you said you want the fastest boat, but now you you don't want the fastest boat, instead you only want the fastest MONOHULL boat. Any more restrictions or limitations we should know about here?

    Perhaps you will take some time to write a clear and accurate list of all the requirements and limitations we should be considering, then post it here. Maybe after you have listed ALL the "rules of the game" it will make more sense for us to continue trying to help you ...
     
  14. ber1023
    Joined: May 2008
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    Location: bermy

    ber1023 Junior Member

    1. it can be multihull but i dont want multihull
    2. 6hp is max and can be fully modifiyed
    3. 42 mile race around a island and is rough on one side
    4. 2 people have to be in the boat


    thats basically all the restrictions
     

  15. water addict
    Joined: Jun 2004
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    Location: maryland

    water addict Naval Architect

    I'll be down there in a couple weeks for the Newport-Bermuda race. You want me to get in touch with you there or is that too late? You could physically show me the boats, might give me some intuition. I might be able to help you out.
     
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