Inboard surface drive small boat.

Discussion in 'Surface Drives' started by Greg01, Aug 15, 2022.

  1. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

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  2. Greg01
    Joined: Aug 2022
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    Location: Chattahoochee, FL

    Greg01 Junior Member

    Thanks for your input, but no. A long tail and transom clip on surface drive are lame efforts that really don't work that well in general use. In weeds and shallows they are suitable. In open water, they are just noisy and boring.

    I found TSD surface drives and they sell compete set up for inboard surface drive for just a little more than the kits cost for transom mounted surface drive. And I can use a light automotive engine with up to 200hp. I will be using a 98hp Honda engine. The weight is distributed more evenly than having all on mounted transom. A big disadvantage of long tails is no reverse. And very slow speed on open water.
     
  3. Greg01
    Joined: Aug 2022
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    Location: Chattahoochee, FL

    Greg01 Junior Member

    I posted the question, started the thread. How and why do call this irrelevant? It answers my question.
     
  4. Greg01
    Joined: Aug 2022
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    Location: Chattahoochee, FL

    Greg01 Junior Member

    Thanks for your input. What I am building is a little more boat than this. A tiller steer and lawnmower engine does not fit my needs. Might as well get a transom mount surface drive kit and engine from Harbor Freight if this is what you want.
     
  5. Greg01
    Joined: Aug 2022
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    Location: Chattahoochee, FL

    Greg01 Junior Member

    Thank you for the input. I like the design of the fitting. But I have to back out of my search. A company, TSD, makes complete inboard surface drive units for about same cost as Mud Skipper sells transom mounted kits. And hp options are very limited. The TSD drive will handle up to 200hp. I will be using a 98hp Honda engine.
    I found TSD after I thought that I would have to make a drive.
     
  6. OCB
    Joined: Dec 2015
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    OCB Senior Member

    I was trying give input to the O.P. needs for 150 HP inboard with tilt and steering. It looks like he will be happy with the downfalls of the current surface drive design.
    The link below is where I posted some very basic line drawings of my EL-60 inboard drive design.
    Baekmo I'm interested in the how much load you thick this deign needs for 150 HP. After in-house testing @ 60 degrees on my best 3/4 X-joint is at 400 lb static load. The solid 3/4" mild steel bar fails under 300 lb.

    Electric Inboard Drive Design EL-60 | Boat Design Net
     
  7. baeckmo
    Joined: Jun 2009
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    Location: Sweden

    baeckmo Hydrodynamics

    "My biggest concern right now is what U joint or CV joint to use,.......".
    Ok this was the original question. I did not want to rain on OCB's parade in your thread, but there are a number of shortcomings associated with that kind of universal joint (btw it is not unique!). If you, as a mechanical engineer, make a rough check on the torques required for your drive (notice the gear reduction necessary for a surface prop and beware the torque variations due to blade forces), you will see that the resulting surface pressures on the sides of the sliding member become very high. With even a slight steering angle, the sliding motion will generate a lot of heat in whatever lubricant present. This heat must be cooled away, and represents a huge loss of efficiency.

    Looking at the picture from OCB, you will see that when angled out, the inner "yoke" is actually presenting its tangential force to the sliding member in a cantilevered position, which generates very high localized pressure along a thin line; it's the familiar "drawer locking effect".

    This universal joint obeys exactly the same kinetics as all existing cardan joints with 90 degree yokes, meaning that it will have a variation of the relative shaft positions during the rotation, the amplitude proportional to the side angle.

    Now, you asked for advice. I understood it as "advice from people with experience from this kind of propulsion", and my answer referred to the suitability of OCB's device for your case; it is simply not suitable due to technical matters. If you, for other reasons find it interesting or want to jump into further experimentation together with OCB, fine, but that is something else, and not relevant to the original question.
     
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  8. Greg01
    Joined: Aug 2022
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    Location: Chattahoochee, FL

    Greg01 Junior Member

    I am the OP. I was looking for suitable swivel to use in steer and trim. I found a manufacture that makes complete drive in China for less than many sell their surface drive clamp on transom kits for. Which is less than what I would pay to have my design made.

    In your drawing angle is extreme. Get motor closer to height with what it is driving. The steeper the angle the greater the parasitic resistance. Your motor is using power to get power to what you wish to drive.

    I stated my first post with, I don't wish to reinvent the wheel. Which is followed by bad advise and persons with no knowledge. A few did know of universal joints that will work.

    This post is done, toast! I am going with a tail shaft unit ready to install. So it is made in China, so is everything you buy at Walmart and parts for your Chevy or Ford you get from NAPA.
     
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  9. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . _ _ _ . . . _ _ _

    Good luck Greg01!
    Post lots of pictures of your efforts.
    My hat is off to those who tried to help you.
     
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