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Discussion in 'Boat Design' started by Guest625101138, Jul 14, 2008.

  1. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
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    Location: BC Canada

    Gib Etheridge Junior Member

    Does anyone here have experience or information regarding durability of the T.E.A. Transmissions size 2 or size 3 type ZP 1:3 three way gearboxes?

    I'm looking at using one of the above coupled by toothed belts/pulleys at 1:3, or, to it's two way counterpart to give me 1:9 and using that to drive one of Hydrobike's 12" X (pitch unknown) cast aluminum props. These props ( 1/2" bore $29.00) are computer designed to 95% efficiency at 1:8.6 gearing. I like it that they look very rugged, are readily available, are inexpensive and they appear to propel the (relatively) inefficient short catamaran hull of the hydrobike at a comfortable cruising speed with very little effort.

    http://www.hydrobikesontario.com/hydrobikes_propeller.htm

    http://www.tea.net.au/

    TEA has a branch in the US.
     
  2. Submarine Tom

    Submarine Tom Previous Member

    Gib,

    I'll be interested to see other responses but from my experience with JavaProp, there is no 95% efficient prop, even theoretically.

    My only point is, I would be suspect of their info out of concern for your design/performance calculations.

    Sorry, I don't have any info on gear boxes for you.
     
  3. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
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    Location: BC Canada

    Gib Etheridge Junior Member

    Hi Tom,

    I didn't really expect 95% to be an accurate number, but I do seem to remember some props discussed previously in the thread to be labeled as up to 98% efficient so it just may be. It's pretty much a non issue though since if it can push the hydrobike along at what appears to be at least 4 mph in some of the youtube videos it ought to do better than that with a relatively long skinny hull which will suit me just fine.
     
  4. I57
    Joined: Feb 2008
    Posts: 172
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    Location: Melbourne, Australia

    I57 Senior Member

    Gib
    I use a TEA transmissions DZ22 1:2 gearbox, it is connected to a bike chain ring to give a 1:7.38 gearing at the prop. Setup works well but then I don't race and its a light boat, other people have had problems with 1:2 gearboxes failing. The bigger you go with the ratios the heavier the gearbox and because of the gearing are not as robust, this has been mentioned earlier in this thread. I have an Involute gearbox which I was using on an earlier boat, it is 1:3.3 is very strong, big and also very heavy 5kg. A 1:1 gearbox for equivalent output with gear step up using belts would work out lighter and stronger.

    Ian
     
  5. Submarine Tom

    Submarine Tom Previous Member

    Without taking away from Gibs request, but while we are on the topic, I am now looking for 1 : 1 box recommendations.

    My crank arms will go directly on the box and the out-put to a shaft drive.

    No racing, 65 - 90 RPM's.
     
  6. I57
    Joined: Feb 2008
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    Location: Melbourne, Australia

    I57 Senior Member

    Tom
    A 1:1 ratio going directly to the prop is going to be a big prop. I got my 1:2 gearbox from TEA transmissions and have found them good to deal with and a good gearbox. Mitrepak is another one but I have not used any of their gearboxes.

    Ian
     
  7. Gib Etheridge
    Joined: Nov 2012
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    Location: BC Canada

    Gib Etheridge Junior Member

    157,

    I remember that the higher the ratio the more likely it is that one of the roll pins that locate and lock the gears in place will shear. Mitrpak now offers a 1:2 three way box, I think it's the T 102, with solid pins and the long shaft ends shaped to accept unicycle cranks.

    Your DZ22 has 15mm shafts and it works well for you, so I'm thinking that the size 3 ZP (1:3) with 19mm shafts should be OK. I'll probably go with that then, and before anything else I'll check the pins and replace with solids if necessary.

    I wish I could just get started with this, but nope, 3 projects (2 paying) to finish first. Oh well, at least it motivates me to get them out of the way.

    I'd love to hear from anyone who has used the TEA size 3 ZP.

    I'd also like to know where one can purchase involute boxes. I've searched the net but only find manufacturers in India and no dealers anywhere. You're not so far from India, that probably helps.

    Here's a link to the Mitrpak T 102.
    http://www.marcopoloboats.com/MarcoPoloBoats/MitrpakDrive.html

    Thanks for the input.

    Gib
     
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  8. I57
    Joined: Feb 2008
    Posts: 172
    Likes: 6, Points: 0, Legacy Rep: 62
    Location: Melbourne, Australia

    I57 Senior Member

    Gib
    The Involute gearboxes as far as I know were made for a pedal boat which was manufactured commercially. It was basically a surfski hull with retractable outriggers and was pedaled upright the same as a bike. Involute contacted me through this thread in 2008 offering me one for sale, as I was looking for a gearbox I bought it and have had good use out of it. It is still servicable but sitting on a shelf in the garage. Don't know if they are still made or if they have any in stock, website is http://www.involutegear.com/

    Ian
     
  9. Scheny
    Joined: Feb 2012
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    Location: Vienna/Austria

    Scheny Junior Member

    @ Gib:
    That looks just like my latest design without weed shedding. My tests showed an efficiency of 82% for such a design, which is really good.

    Also the price is very good, as a single produced entity of my design actually lies around 100$. Mass production could lower it to 15$.
     
  10. Submarine Tom

    Submarine Tom Previous Member

    Ian,

    It's not a big prop, it's HUGE!!

    I haven't done the calculations yet but 24" (61cm) is anticipated.

    I suspect my choice (gear box) will come down to weight and price.

    Thanks Ian.
     
  11. Submarine Tom

    Submarine Tom Previous Member

    It's called a WaveBike, there's a great promo video of it on YouTube.

    They went out of business but still answer emails from their video E'ddress.

    Very nice guy, I forget his name.

    It has direct handle bar "steering" to the midship canard for roll control and brake lever

    steering to a rudder. Brilliant!
     
  12. Coach Dave
    Joined: Jun 2011
    Posts: 70
    Likes: 4, Points: 0, Legacy Rep: 40
    Location: Malabar, FL

    Coach Dave Junior Member

    prop efficiency

    Efficiency in the 85 to 88% range is possible for a prop operating at its designed speed and load. http://www.boatdesign.net/forums/inboards/prop-size-24423-2.html See posts #17 & #19. Notice the high aspect ratio (diameter to chord ratio) that is typical of high efficiency lightly loaded props. If you fiddle around with javaprop a bit you can get some predictions of even higher efficiencies but the program minimizes drag by making the prop blades too thin. The problem is that such thin blades in water would develop enough stress to flex or even buckle the blade - ruining its efficiency. The Hydrobike's prop has a lower aspect ratio which I would expect to more robust, more drag and less efficient. The robustness means it should be able to take more of a beating and continue working. That's important if you are counting on the prop to take you several miles to get back home.

    Dave
     
  13. Coach Dave
    Joined: Jun 2011
    Posts: 70
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    Location: Malabar, FL

    Coach Dave Junior Member

    1:1 ratio

    Since you are running a 1:1 ratio have you considered skipping the gear box and using a double universal joint instead? See Jeremy's post #1689. It may be lighter and less expensive. You would need one that can handle your torque.

    Dave
     
  14. Submarine Tom

    Submarine Tom Previous Member

    Dave,

    I am planning on using TWO of them!

    But I don't see how adding two more would eliminate the need for a gear box.

    I need something to mount the cranks on.

    There is no chain or chain wheel.
     

  15. Coach Dave
    Joined: Jun 2011
    Posts: 70
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    Location: Malabar, FL

    Coach Dave Junior Member

    Tom,

    I understand now that you need an axle to mount the cranks. The drive assembly for a shaft drive bicycle may work in your application. http://webbicycle.netpaths.net/technology.php
    They sell the entire bike for $229 and up depending on model. Maybe you can buy just the drive assembly. It is hard to tell from the picture what the ratio is for the front bevel gears. If the model on this other site is accurate their unit is not 1:1 on the front bevel gears. http://www.dynamicbicycles.com/Animation/dynamicpopup.html I don't know if both sites are using the same drive assembly.

    Dave
     
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