Thai racing longtail

Discussion in 'Powerboats' started by joeu3, Sep 26, 2012.

  1. Frosty

    Frosty Previous Member

    Here is a few guys resting in the shade of the bridge over the river Kwai.

    Click onto it for full size and aagin for zoom
     

    Attached Files:

  2. joeu3
    Joined: Sep 2012
    Posts: 30
    Likes: 10, Points: 8, Legacy Rep: 52
    Location: Summerland Key

    joeu3 Junior Member

    I really need help on the propeller..
    I don't know where to begin.
     
  3. joeu3
    Joined: Sep 2012
    Posts: 30
    Likes: 10, Points: 8, Legacy Rep: 52
    Location: Summerland Key

    joeu3 Junior Member

  4. Submarine Tom

    Submarine Tom Previous Member

    Begin with Gerr's book The Propeller Handbook.
     
  5. Submarine Tom

    Submarine Tom Previous Member

    How's the propeller search going?
     
  6. joeu3
    Joined: Sep 2012
    Posts: 30
    Likes: 10, Points: 8, Legacy Rep: 52
    Location: Summerland Key

    joeu3 Junior Member

    I was going to go with a 13 spline, a lot of the people call them super speed master propellers,they're counter rotating and look like they will get the job done. I was going to settle with a 10 1/4 x 19. But, I've been talking with a Thai guy and I gave him all my information and he has recommended a prop. I already weighed out the pros and cons, I believe I'm going to go with the thai prop. It's weird shaped, but I'm sure it's designed that way for a reason.

    [​IMG]
     
    BrissoDamo and Submarine Tom like this.
  7. El_Guero

    El_Guero Previous Member

  8. Submarine Tom

    Submarine Tom Previous Member

    Well, that should do the trick!!
     
  9. baeckmo
    Joined: Jun 2009
    Posts: 1,189
    Likes: 143, Points: 63, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    Beautiful beast! The propeller issue is very tricky, since you are far off anything "standard". The rare info on the subject point towards a lightly loaded surface piercing chopper style screw. Surface piercers tend to "balance" in vertical position when roughly 50 % submerged, and I guess that this would be an important quality in this application.

    So, trying to match a surfacing chopper to your engine and the expected speed (from hp/weight ratio I think 80 knots may be possible) it all boils down to something like 8.5" x 16.5 à 17", two-blade. This is certainly smaller than your guess, but the thrust from a prop blade with a substantial cup comes at a low angle of attack. And a bigger dia could well be used with less submergence, but then it would be more difficult to balance, so as usual, its a compromise.

    Do you know the dia and pitch of the screw suggested by your Thai friend? It will be very interesting to follow your progress; we have far to little open info on those props!!
     
  10. tom kane
    Joined: Nov 2003
    Posts: 1,766
    Likes: 45, Points: 58, Legacy Rep: 389
    Location: Hamilton.New Zealand.

    tom kane Senior Member

    The original long tail propulsion. Paris Exhibition circa 1900.World`s first outboard motor made available to the public.. the propulsion idea is french the hulls used now are native to the specific area where they are built. Not much of a view of the props though. Like every thing they inspire local innovation and improvement.
     

    Attached Files:

  11. Frosty

    Frosty Previous Member

    All the props Ive seen are made by AAA. They start at 2 inch di and with taper and a machined key they are ridiculous prices starting at less than 1 dollar.

    All the range of AAA going up to (guess) is 24 inch is taper and key. All are 2 bladers.

    In most hardware stores shaft and props hang ready for sale along with reduction gears and duplex chains.
     
  12. Samakkeesilp
    Joined: Jan 2013
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: UK

    Samakkeesilp Junior Member

    Racing Boat

    Go to Thailand ;-)
     
  13. joeu3
    Joined: Sep 2012
    Posts: 30
    Likes: 10, Points: 8, Legacy Rep: 52
    Location: Summerland Key

    joeu3 Junior Member

    My Thai friend has been trying to get me to go.
    I told him one day in the future, seems like a nice place for a vacation.
    As an update, inside is done waiting for a non windy day to clear coat, and the outside is almost all faired to flat. Been planning the engine mount/pivot, figured the gas tank size and placement, battery, bilge pumps, lights, etc.. Also, have started designing the artwork for the outside.
     
  14. Frosty

    Frosty Previous Member

    Errrmm where did you meet this Thai guy?
     

  15. joeu3
    Joined: Sep 2012
    Posts: 30
    Likes: 10, Points: 8, Legacy Rep: 52
    Location: Summerland Key

    joeu3 Junior Member

    I've never met him in person, I met him on a different forum dealing with PWC's, and I noticed his avatar was a longtail. I told him I was building a longtail and he's been helping me ever since. Nice guy, funny we met through something completely unrelated, dealing with pwc parts.
     
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.