Inboard Propulsion Video

Discussion in 'Hydrodynamics and Aerodynamics' started by majorm, Aug 14, 2013.

  1. majorm
    Joined: Apr 2012
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    majorm Junior Member

    Inboard Propulsion Video Search

    I have been looking for a video showing a inboard boat running from underwater so I can see the props rudders and shafts. I was just curious how this cut through the water and where obvious drag was taking place. Its obvious whats causing the drag (shafts, struts, rudder, prop?) but I wanted to see if you could visually see where the more problematic areas are. If nothing else it just seems like it would be a cool video to see.
     
  2. tunnels

    tunnels Previous Member

    whats the video ??

    Post the link to so we can see !!:idea:
     
  3. majorm
    Joined: Apr 2012
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    majorm Junior Member

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

    How do you expect to see anything, other than the rotation of propellors, or cavitation ? Since when is drag visible ?
     
  5. tunnels

    tunnels Previous Member

    they are just sterndrives !! they are almost the same as outboard legs so drag applies the same They have twin propellers counter rotation so they should track easier in a straight line . and I see its fitted with the new docking system so they move independent of each other . drag is confined to the actual gear case shape and the leg its self !! they are a pretty basic foiled shape and if you get on the net and look at the shape of stern legs they all very much the same till you get into racing and high speed stuff then things change dramatically!!!
    Have a look for Mercury racing at the outboards and sterndrives and take particular notice of the underwater shapes of gear casings and propeller's to . some of the older and normal gear cases can be fitted with a nose cone and faired in and repainted ! kits are available so that's something else to eye ball . The set up height of out boards is important when you talking of efficiency and speed because those two things go together.
    electric Hydraulic Jacking plates with dash control to raise and lower during use to get the maximum is something else .
    Racing and speed you will or should learn more than just pottering about with standard off the shelf units !!. setting up any sterndrives or outboard is really important and just a couple of mm in height change can make a big different to steering , performance and handling of any unit single or twin installation . To get the best and learn more study racing boats !!:D:p
     
  6. majorm
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    majorm Junior Member

    Im no expert or even novice as you can tell so I think I have used the wrong term. What I really want to see is the fluid movement but as you said you cant unless dyes or cavitation are present. So for the video I was referring to bubbles, swirls and anything visual showing where the changes in the water movement are.
     
  7. BMcF
    Joined: Mar 2007
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    BMcF Senior Member

    Inboard propulsion using props, struts and shafts (what the OP is asking about).....is what?



    I have some examples of stills taken from underwater video filming of a high speed yacht passing over the camera. It's not an uncommon way of troubleshooting an installation that is not meeting expectations. I'll see if I can find a couple of the stills...
     

  8. BMcF
    Joined: Mar 2007
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    BMcF Senior Member

    Here is a sample. Its actually short video clip..not a still. Although its not real clear in this form, after some editing and enhancing of still shots, the information is very useful. On the vessel in question, the underwater work resulted in modifications to the strut design as well as the rudders.
     

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