hydraulic propulsion for tugboats??

Discussion in 'Propulsion' started by tugboat, Nov 19, 2010.

  1. tugboat

    tugboat Previous Member

    ok- so one of the members on here suggested two small hydraulic engines for my tugboat-(twin screw) i admittedly have no experience with hydraulics or thier setup-
    i have done some research on the web, and it appears these slow turning high torque and high output engines would be perfect for a large slow turning prop application- and if so- why havent i heard of this being done before??...
    what would be needed to set up a small hydraulic system on a boat for propulsion?
    from what i can tell a small engine is needed to run a pump of some type and then oil is pumped into this small engine and returned to the pump to produce huge torque . i am looking at an engine from

    note- 400 rpms- direct reversing. costing 250.00 and unknown hp but using torque calcs i get 175 hp(?) not sure if this is correct- at 400 rpms.why isnt this used for commercial boats needing huge torque and hp?

    if these are so powerful why are there not more tugboats using this system? ive been around tugs for 15 years and never heard of a hydraulic drive for a tug. but it seems like such a great idea...(thanks Bert for informing me of this possibility)
    anyone who knows how to set up a system and what hp motor, pump, valves etc for the motor in above link would be needed to run this engine??
    i am considering it but need to know more before i do...
    I have many questions and know almost nothing about it-
    do i need some type of clutch system for the motor??
    any info on hydraulics and the feasability and costs of it as a means of propulsion is greatly appreciated..

  2. tunnels

    tunnels Previous Member

    The best write up and description to Hydraulic drives is in the Vetus catalogue !!:)
  3. Submarine Tom

    Submarine Tom Previous Member

    Hydrostatic drive would be the way to go but why.

    They are expensive, complicated, heavy and inefficient.

    All you need is a good, small diesel and a good prop with a rudder...

  4. tugboat

    tugboat Previous Member

    Thanks Tunnels-ill look into it...much appreciated...
  5. tugboat

    tugboat Previous Member

    Hey Tom--yes very true--it would be easier...no doubt about that--I like to experiment i guess--im just looking into this possibility right now--for me I really like twin screws...you can do more with them...in the end if i have to ill go simple with a small diesel. I could use my caterpillar d318 which is NOT small and could run a 36x 34 prop or larger pitch-very nice for the tug...but more pwoer than ill ever need(at least i think so right now...)

    or i could gear the petter 20 hp to 5:1 and it would spin about the same size prop those old diesels were built to last forever and the nice chug chug sound of the petter sure is nice too..like a small steamboat sound...

    but wouldnt it be nice to have twins?...for agility. Are hydraulics really that much mroe than a good gear and new diesel? Just curious...if so well i suppose its easier to go with the small diesel...the twin ev motors would be nice too...i have about 12-18 months to decide. so ill do some research and learn...

    thanks for the response...

  6. tugboat

    tugboat Previous Member

    Is hydrostatic drive the same as using a hydraulic motor?..sorry for my ignorance on this subject...and if not what would make them differ?
  7. TeddyDiver
    Joined: Dec 2007
    Posts: 2,584
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    For a tug forget Vetus.. Go to Bosh-Rexroth http://www.boschrexroth.com/business_units/brm/en/index.jsp or Eaton http://www.eaton.com/EatonCom/Markets/Hydraulics/index.htm
    Look for closed circuit units (open is for toys and occasional use), variable displacement piston pumps are most suitable and for a motor might some radial unit be best.
    Not quite right.. they are only expensive. Complicated if you don't understand it. Heavy? They have very effiecient power to weight ratios (only CPP is wins in this regards ;) just a hint). Effiency for such setup would be around 80%, so not so bad..
  8. Techecho
    Joined: Nov 2010
    Posts: 5
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    Location: Vancouver BC Canada

    Techecho newbie to boat design

    Hydraulics have many advantages:
    1) The power plant (engine –gas or diesel ) can be placed anywhere ( motor and hydraulic pump with two lines to drive units )
    2) The power plant usually runs like a generator two RPM's idle with no load and a fix RPM under load ( reduced ware on the engine )
    3) The drive units are the same size as a diesel transmissions would be
    4) The drive units can be almost any RPM hoarse power you require ( there are units that can run up to 7-8-9000 RPM
    5) The speed control is done by diverting the oil flow to the drives or letting in build to pressure causing the engine to go to idle.
    6) Twin screws running different directions different speeds from one power plant

    Other powered equipment can run from the plant
    7) The tow cable for the tug can be run from the same plant
    8) The anchors winch can be run from same plant
    9) Some bow thrusters are hydraulic

    Some of the boom boats use hydraulics ( allows the drive to rotate 360 deg. )
  9. Submarine Tom

    Submarine Tom Previous Member


    All the power to you, I was simply offering my opinion. I have a 60 GRT commercial towing certificate. Yes, twins are nice, but I wouldn't do it, I don't feel it's necessary or worth the expense. Only my opinion, but I thought that was what you wanted here.

    Google hydrostatic drives. I've used them extensively operating sno-cats and some farm machinery.

    Good luck, keep us posted.

  10. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Gee Tug...thats complicated, expensive gear. Proportional controllers, valve blocks, elecrics, oil coolers, big oil tanks , plumbing, piston PTO pump. Whoa. Hardly worthwhile unless you need special abilities like a retractable leg or something for your tugg'n.
  11. Lurvio
    Joined: Jul 2009
    Posts: 283
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    Location: Mid of Finland

    Lurvio Mad scientist

    You can get by with a lot less. The minimum gear you'd need for example is (for one diesel, two props setup) a gearing to power multiple pumps, two drive pumps (axial piston, +/- 45 degrees variable displacement, manual control) plumbing, two fixed displacement motors and reduction gear before prop shaft. Oil cooling is a good idea also.

    Me being who I am, I'd go a bit further and place the motors and gear in pods, and make my very own poddrives. :)

    Edit: Just an afterthought, place the oil tank at the bottom of the boat and it cools itself. Just better use some biodegradable oil in case you get a hole in the tank some day.
    1 person likes this.
  12. apex1

    apex1 Guest

    Concur, why the expense and added complexity? a single Diesel is all one needs.
    The argument about better maneuverability does not counter the better argument about having a bigger wheel. The latter is what a tug needs.


    I fear you still have stern tow jobs in mind. Your comment on the other thread lets one assume so. I know you are stubborn as a mule, no worse, but in this case, rethink that, it will possibly kill you. Don´t be a fool, stern tows kill professionals, which you are not.


  13. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    For tugs, electrical drives are fairly standard. You can position the generators any place that is convenient. Pretty much everything is off the shelf. Contact the suppliers with your specifications and they will tell you what you need.
  14. tugboat

    tugboat Previous Member

    Hi Tom--no offense intended in any of my posts so I apologize for any confusion, i certainly am interested in opinions..i have no idea about hydraulics. so this is why i am asking. Thats great you have you 60 ton endorsement!. I was looking at getting mine. It means lots of seatime. I dont really like to work away from home that much. where did you do your time?
    im just asking questions at this point seeing if the D.E. system is more complicated...ill keep you posted as to the progress..i still have a lot of prep work to do--gotta build a shed and still move my cat. Get the steel Nested and cut.
    as you know its getting cold now..
    the single engine - the twin screw D.E. and the twin Hydrualic drive are options--the least expensive will be the one that wins..although i really want the twin screw.

  15. tugboat

    tugboat Previous Member

    Yea--I thought there must be a good reason it hasnt been used more...Is there a way to make a simpe cost effective system??? if not ill go back to my original plans...Thanks Mike!
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