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  1. #1
    Petty Officer 3rd Class
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    Default hydraulic drive why not?

    Not sure if i have posted this in the correct area,...
    why has no one ever done a hydraulic type drive on a boat?
    no big hole on the transom would be needed just a couple hoses,
    to a hydraulic motor from a hydraulic pump attached to the engine?
    might take some engineering to build some sort of inboard outboard like
    leg to hold the hydraulic motor, other than that you think it would be simple.
    matt

  2. #2
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    Default Re: hydraulic drive why not?

    very simple.
    very inefficient.
    takes a tremendous amount of power from the hydraulic power suply unit.
    and eventually its gonna leak leading to a liability issue.
    its been done on commercial applications though.
    it was tried on some tugs using a cyclodial propulsion system.
    kinda like why they quit using steam.
    no tech questions by PM, they wont get answered.
    you have to be trusted by the people that you lie to .

  3. #3
    Rear Admiral Howard Sterndrive's Avatar
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    Default Re: hydraulic drive why not?

    If the question is why, the answer is money.

    So, we take a beautiful new hull, and blast a giant hole through its butt. And seal it up with rubber bellows.

    When we could just throw 2 hoses over the transom to a hydrostatic motor (a 3rd small hose for case drain). We could then put the engine in the middle, or the bow...for the price of a few extra feet of hose..... engine sideways if ya want...

    I work on hydraulics for a living. My flow meter doesn't lie. A modern excavator can deliver about 95% efficiency with a piston pump.
    100HP at the flywheel will measure 95 Hydraulic HP (gpm X psi /1714)

    Hydrostatics offer infinitely variable drive ratio. Forget selecting prop pitch. You can rev the engine up into it's power band, then swash the pump as fast as you want.
    You could rip your skiers arms off!

    It's all to do with money. Hi efficiency hydraulic components are very expensive.
    and heavy....
    and expensive to cool, and filter... would take some serious heat exchanger to get rid of that 5%

    how many boat techs are going to be trained to fix it...
    that would be a huge cost to the industry
    Baba-buoy.

  4. #4
    Rear Admiral Howard Sterndrive's Avatar
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    Default Re: hydraulic drive why not?

    I actually picked up a little hydrostatic unit called a hydra-troll (from an iboats member a while ago)

    It has a hydraulic pump with a clutch like an A/C compressor, and a little hydraulic motor with a 10"X 13P prop that is designed to mount to the skeg of an outboard or outdrive

    It is only made for trolling... no serious pressure or flow capabilities

    Some day soon(ya right) I am going to put it behind my 12' cartopper with a Briggs or Honda ~6HP up in the bow of the boat.

    all my research on hydra-troll shows they went out of business very fast
    Baba-buoy.

  5. #5
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    Default Re: hydraulic drive why not?

    I sure wouldn't want to pay the environmental fines if a hose blows. I would think it would be more practical for an inboard application thus containing any leaks in the bilge where they could be properly contained.

    Or put the hydro on an existing sterndrive with all the lines inside the hull????
    '77 Sea Ray 260 Sundancer
    Twin Merc-165 I6

  6. #6
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    Default Re: hydraulic drive why not?

    Quote Originally Posted by Howard Sterndrive View Post
    and expensive to cool, and filter... would take some serious heat exchanger to get rid of that 5%
    with a lake of water around you one would think cooling wouldnt be much of an issue...

    how $ are we talking, a inboard outboard setup is stupid money new.
    never mind the cost of an outboard!

    as for the enviro issue that keeps coming up isnt there bio and vegi oils out there?

    matt

  7. #7
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: hydraulic drive why not?

    Just about all the big bow thrusters are hydraulic powered.
    73 de Rick
    ----------------------------------------------------------------------------------
    I use xxx oil and have never had a problem........
    1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME,
    Formerly OMG 460 King Kobra powered
    1947 Stinson 108-2 Station Wagon
    , Franklin 6A-335B. Hartzell CS 2-blade prop
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    All PM's cheerfully answered! Please ask tech questions in the appropriate forum so everyone's included

  8. #8
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    Default Re: hydraulic drive why not?

    I agree that there are bio oils that would cause much less impact then smacking your lower on a rock and dumping synthetic petroleum blend in the water. Besides anything we could spill would look like nothing compared to the &^%$# at BP.

    Worried about cooling? Run SS pipes down the keel to the pump.

    I think the time is right!
    When will people learn that impellers require regular
    replacement and are not drive it till it pukes items?

    1984 Regal Medallion 195
    3.8 V-6 with the dreaded
    OMC Stringer Drive.
    2003 Avalanche w/Hypertech

    If it ain't fixable - don't break it!

  9. #9
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: hydraulic drive why not?

    Hydraulic pumps and motors are not nearly as efficient as gears.

    Boats are terrible gas hogs already, I wouldn't want LESS efficiency!
    73 de Rick
    ----------------------------------------------------------------------------------
    I use xxx oil and have never had a problem........
    1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME,
    Formerly OMG 460 King Kobra powered
    1947 Stinson 108-2 Station Wagon
    , Franklin 6A-335B. Hartzell CS 2-blade prop
    -
    All PM's cheerfully answered! Please ask tech questions in the appropriate forum so everyone's included

  10. #10
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    Default Re: hydraulic drive why not?

    Don't fall of the fence there HT32BSX115.
    When will people learn that impellers require regular
    replacement and are not drive it till it pukes items?

    1984 Regal Medallion 195
    3.8 V-6 with the dreaded
    OMC Stringer Drive.
    2003 Avalanche w/Hypertech

    If it ain't fixable - don't break it!

  11. #11
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    Default Re: hydraulic drive why not?

    like I say, to move an average 25ft boat using hydrostatic is terribly inefficient.
    could it work,yes and very well.
    it will require about 150 HP prime mover,a very large heat exchanger to cool the oil.
    and some type of gear reduction as props typically dont like to rotate faster than about 2500 RPM at the shaft.
    its kind like using a gas turbine ,works very well but its very expensive.
    no tech questions by PM, they wont get answered.
    you have to be trusted by the people that you lie to .

  12. #12
    Rear Admiral Howard Sterndrive's Avatar
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    Default Re: hydraulic drive why not?

    efficiency is all relative to what you spend

    A modern excavator pump or motor has barely a trickle of oil leaking through the case drain line - and that is even intentional to flush the case and remove heat. At 95%, it is as efficient as any sterndrive. Outdrives get hot too.

    No gear reductions are required. Pump displacement to motor displacement creates the "ratio". By making the pump infinitely variable, you can have infinitely variable ratio controlled by a lever, servo, or ECM (EDC), including reverse in any ratio when you use a bidirectional pump.

    I've worked on lots of $25000 pumps though, so don't look for this stuff in a recreational boat soon.

    Quote Originally Posted by nowback View Post
    how $ are we talking, a inboard outboard setup is stupid money new.
    never mind the cost of an outboard!
    as a heavy equipment tech, it seems to me they're giving the stuff away - the rip off part is the lack of after sale support, but that's another thread.
    Baba-buoy.

  13. #13
    Fleet Admiral HT32BSX115's Avatar
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    Default Re: hydraulic drive why not?

    Quote Originally Posted by cr2k View Post
    Don't fall of the fence there HT32BSX115.

    I'm leanin'............but I'm holding on pretty good!!!
    73 de Rick
    ----------------------------------------------------------------------------------
    I use xxx oil and have never had a problem........
    1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME,
    Formerly OMG 460 King Kobra powered
    1947 Stinson 108-2 Station Wagon
    , Franklin 6A-335B. Hartzell CS 2-blade prop
    -
    All PM's cheerfully answered! Please ask tech questions in the appropriate forum so everyone's included

  14. #14
    Petty Officer 3rd Class mdlee's Avatar
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    Default Re: hydraulic drive why not?

    I Think the Idea of a hydro drive is really cool,,, That being said-- I run a small equipment company-- Tractors, Backhoes, etc.. And I can tell you when hydro components fail under a load it can be ugly and very messy,,, Very Hot hydro fluid everywhere,,, I cant imagine that under the deck of my boat... not to mention the fire hazard.. Still a cool idea though!
    GO GATORS !

  15. #15
    Seaman mariner1900's Avatar
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    Default Re: hydraulic drive why not?

    Quote Originally Posted by HT32BSX115 View Post
    Just about all the big bow thrusters are hydraulic powered.
    Actually vast majority of large bow thrusters are direct driven by an electric motor with hydraulics to control the propeller pitch.

    Some small thrusters for motor yachts etc are hydraulic but most are electric.

    If hydraulic drives were viable alternatives I think the main marine industry would have adopted them over the 2 main alternatives being used, which are direct/geared drive or electric drive.

  16. #16
    Petty Officer 3rd Class
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    Default Re: hydraulic drive why not?

    I know next to nothing about hydraulics just seen pumps and motors used
    in a few different places and thought it might be simple to apply to a
    boat.
    $25000 there are enough reasons not to go there

    matt


    Quote Originally Posted by Howard Sterndrive View Post
    efficiency is all relative to what you spend

    A modern excavator pump or motor has barely a trickle of oil leaking through the case drain line - and that is even intentional to flush the case and remove heat. At 95%, it is as efficient as any sterndrive. Outdrives get hot too.

    No gear reductions are required. Pump displacement to motor displacement creates the "ratio". By making the pump infinitely variable, you can have infinitely variable ratio controlled by a lever, servo, or ECM (EDC), including reverse in any ratio when you use a bidirectional pump.

    I've worked on lots of $25000 pumps though, so don't look for this stuff in a recreational boat soon.



    as a heavy equipment tech, it seems to me they're giving the stuff away - the rip off part is the lack of after sale support, but that's another thread.

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