Backup Hydraulic Drive

Discussion in 'Inboards' started by Chuck Losness, Sep 8, 2011.

  1. Chuck Losness
    Joined: Apr 2008
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    Chuck Losness Senior Member

    Some of the boats that I am considering for my next boat are single engine power boats in the 35' to 40' size range. Because help in the case of a break down is generally not available in the areas that I cruise, you need a back up / get home power source. After reviewing the different options, a hydraulic drive powered off the generator seems to be the best solution for me. I have searched the internet for information on how to determine the size of the motors, pumps, etc. without success. I am not interested in exploring different options such as electric drive or sails. I am focusing solely on hydraulic drive for the back up get home power source. Please do not take this thread off topic.
    So can anybody point me to a book or other source for information on how to determine the size of the motors, pumps and diesel engine to drive the pump.
    Thanks for your help.
    Chuck
     
  2. Stumble
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    Stumble Senior Member

    Chuck,

    To figure the engine size, just determine how much hp you need to travel at an acceptable speed if it was driven by a direct drive diesel, then add 30% to the hp requirement due to hydraulic inefficiency.

    Alternatively, have you looked at diesel high thrust outboards?
     
  3. dem45133
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    dem45133 Junior Member

    hummm. similar situation, but on a sail boat

    Did you ever get the info you needed? I am researching the idea of using hydraulics to be the main propulsion for a 27 ft sailboat and need to design it up. It'll have a 65 hp industrial diesel going to hydraulic motors incorporated into twin lower units from two outboard built into twin rudders. Could go direct to prop shaft or use the down shaft and gear set already in them if hydraulic motors are built that will turn fast enough for the 2.?:1 gear ratio out boards have. I prefer this as it simplifies Fwd/Rev by using the gears in the lower unit... also the hydro motor is then above the water line... something they were /are not designed for in their seal systems.

    Several advantages to over powering and re ruddering. One its needs more authority in the rudder under sail anyway... and I can't stand the screaming 12 hp 2 cycle outboard it currently is. The excess hp and twins props will allow for differential thrust for steering and breaking in tight windy quarters... cruise the at hull speed will be a low rpm which won't bother me any either. I also will be converting it into more of a motor cruiser by shortening the main and therefore raising the boom for canopy clearance as well as going with wheel steering instead of the tiller. Its a water Winnibago and doesn't sail all that well anyway... 1978 Bayliner Buccaneer 270, outboard version, but its shoal draft and on a float on-off triple axle trailer I built for it and the Cummins will pull it anywhere, so it has its advantages over marina bound boats... besides it lives in a shed at home when not in use and doesn't eat but when I let it)

    Several reasons I'm thinking along this line.... costs is the biggest... I already have the engine anyway and I suspect i can locate a hydrostat pump for it (as many were set up this way in their industrial app.) Hydraulic system cooling will be through a second raw water heat exchanger (the other is the engine's cooling)... I have two good lower units from old 105 hp Chrysler outboards... I also have the skills and the shop... including machine tools. I could power twin conventional shafts from one pump but that means through hull seals and the constant leakage potential which would be nice to minimize.

    Not putting 10-15k in re-powering a 30 year old boat... so new or marina work is not an option. I also have no problems thinking outside the box. Do it all the time.

    Dave
     
  4. Stumble
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    Stumble Senior Member

    Dem,

    I think you are seriously over powering your boat. By orders of magnitude. My 30' sailboat is using a 3.5hp gas outboard... And we're still overpowered. The 39' sailboat I own has a 40hp diesel, going to a 65hp for a 27' boat is going to cost you in a lot of ways down the road. Fuel efficiency is obvious, but also the weight penalty, size, boat trim, ect.

    Adding hydroids to this, and twin hydrolics at that is going to add so much drag to the boat, you may be looking at giving up 2kn just for the props and shafts, and sailboats don't really need the turning advantages of twin engines since the keel and rudder make mauverability pretty responsive.

    Thinking outside the box is great, but in this case I think you are adding huge amounts of complexity, cost, and weight, for no discernible advantages.
     
  5. FAST FRED
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    FAST FRED Senior Member

    HYD get home DRIVE CAN BE DONE WITH AT LEAST 2 METHODS.

    The first is to install a shaft with sailboat style folding prop that will move the boat at SL .8 or so .
    This is for the real belt and suspenders folks that fear either engine or tranny failure OR the main shaft and prop crapping out.

    Since on most cruisers a shaft or prop failure is not common ,some folks will prefer to use a thrust bearing and a short intermediate shaft that is easy to disconnect.

    Then a motorcycle style chain or flat belt is used from the hyd motor to the shaft.

    This may take longer to get operating than the sail prop , but is probably better if you have a long way to go.

    A hyd system should be used for most concepts that would normally use an electric DC motor. Bow thruster , windlass, up to 6KW of AC electric (CHEAP) GET HOME AND REEFER OR COMPRESSOR MOTORS (scuba) .

    A huge advantage of all hyd is no time limits , crank up the small hyd pack and the bow thruster and windlass have almost no limits.

    On newer engines Hyd start is an OTS (off the shelf) option.

    Dead batts , so what , dead hyd resivoir , so what!

    A few min with a hand pump will get enough pressure to start any engine in a small (under 75ft ) boat.

    FF
     
  6. dem45133
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    dem45133 Junior Member

    I replied to the original 2 year thread as it was similar. Hydraulic design. What I am considering is my main power source for a boat that was only an outboard. The out board works but leaves a LOT to be desired in several ways. Here is my thoughts about re-powering.

    1) at 6500 lbs and more than average freeboard, the outboard has a heck if a time maneuvering the bow in a cross wind.

    2) it also almost didn't prevent it from ramming into a dock when in this same 25 mph cross wind, once realized she wasn't going to swing around into her berth... 100% reverse simply could not supply enough reverse thrust!

    3) I want 100% control of what it does in ANY wind condition in close quarters. Differential thrust allows for part of this. Excess hp for braking also helps.

    4) 65 hp just happens to be what I have. A 2004 Duetz oil cooled F4M2011 I bought for $75 with a bad cylinder due to swallowing a valve. Since I have machine tools I can build a custom sleeve. So I'll have a low cost plant that will almost never be at full throttle... yea is overpowered, but the only time I'll demand that from it is in an emergency braking situation. Criuse will be at 1/3 rpms and 1/4 power or so. Fuel efficiency shouldn't be all that bad... its not working hardly at all. It weighs in at ~650 lbs if I remember, only a couple hundred more than the VP MD7A 13 hp inboard that Bayliner installed in the inboard version of the same boat. Modern diesels like the Duetz weight a lot less per hp than they used to. Its a nice tight compact design and will physically fit in the MD7A engine compartment too. I also have an MD7A and transmission and the compartment for it from a sister boat I salvaged... but it will have the same lack of braking the 12 hp outboard does and even less maneuverability.

    5) For sailing... even with the outboard... (which still in the water due to a poorly designed mount it came with and can not be reached from the top over the transom...)... I let the prop free spin in neutral... doesn't seem to effect it all that much. If I use the 105hp Chrysler lower units they will be in neutral too... prop(s) just free spin turning only a short shaft a few inches long in its bearings. Can't be all that much drag at the few knots she'll ever do under sail. Hull speed is only 7 knots and no real way to change that.

    6) Since I need to build a better rudder anyway and am going to wheel steering... not hard to build two.

    7) Its an imitation sailboat, known in the circles as a water Winnebago... sailing efficiency is lacking anyway. Almost impossible to tack into the wind. Side slip is awful due to the shoal keel and excessive freeboard. Since it is a fully depreciated $800 boat, it matters not how I modify it. It has a lot of cabin and sleeps 6 with a full 6 ft headroom which my wife needs being 5'11". I plan to convert it to a motor cruiser with a permanent canopy and wheel steering. Cooking in the sun, dodging the low boom, and tiller-ing leaves a lot to be desired. I'll sail when the winds are right for it and I enjoy that... but I'm tired of fighting it when they are not. Someone before me added another 300 lbs of steel weight to the lower edge of the keel... They were through bolted and leaked... they are all glassed in now and water tight... but add their own drag. The jib is 150% and I seldom open it full up...since in a strong gust the rudder can't off set it (swinging down wind) and it will heal to 45 degrees in this state thereby un-nerving my wife big time. For sailing its a sow's ear and can not be made into a silk purse.

    So I still need to locate and study a pump and a pair of motors that I either conventionally shaft or incorporate into the lower units. I need to design it right as I do NOT want ANY hydraulic squeal that is fairly common on ag and industrial equipment... If this is not possible... I'll do conventional single inboard shaft and depending on the V-drive and transmission I may incorporate a shaft disconnect system to allow for true free wheeling of the prop. I'm not all that excited about the folding sail props as they reportedly are not all that good for reverse as they depend on centrifugal forces to stay open in reverse and I'm obviously partial to good brakes. I'd also figure out some kind of home made bow thruster. Although I'm not paying 300% or 500% or 1500% prices for something simply because its associated with marine. You wouldn't believe what V-P gets for parts that are NO different in duty than any other industrial high load continuous duty working application. $160 for one set of piston rings for ONE piston... another 160 for each set of rod bearings... they're nuts.

    Another option is to find another boat.... the 1 ton can pull up to 16000 gross trailer wt and I designed the trailer to go up to 32 ft and 18000 gross or so. I also do not care if I need to permit a wide load but I'll not do a CDL for private property that's not for hire... even if I go the semi route and a boat hauler and it weighs 80k (I've been thinking on restoring an older Mack someday). Its NOT commercial commerce as 49 CFR is addressing. I drove OTR for three years of my life back in the 80s long before CDLs, so I can pull anything. But deep keels present a problem as it has to live on the trailer when not in use. All our toys have to be near 0 for fixed costs.

    So..that's my thoughts on the matter....

    Dave
     
  7. michael pierzga
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    michael pierzga Senior Member

    I dont like the idea. I have a 30 kw PTO on the main engine for hydraulic functions. Its a complex expensive system.

    I think I would investigate a Belted ? electric motor on the prop shaft electrically powered by the generator.

    Also consider is that a probable cause of drive train failure would be prop or shaft damage. Your backup system wouldn't work if you needed the shaft. .

    Another line of thought would be the use of your tender outboard. Perhaps an extra long shaft model and a well thought of transom bracket. Perhaps a bracket on genoa tracks and cars . Load the motor in high position then lower into drive position. Something like 15 or twenty hp
     
  8. iceboater
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    iceboater Junior Member

  9. Stumble
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    Stumble Senior Member

    Ok, for a little perspective, my Irwin 54' with 46,000lbs displacement was bought with the bigger engine, a 115hp turbo charged diesel, the Gulfstar 50 was at 32,000lbs displacement was sold with a 85hp diesel as an upgrade... The Easterly 30's at 9,000lbs are a high freeboard kind of unwieldy boats came with a 15hp engine. You are orders of magnitude overpowered.

    1 & 2) My guess is that you don't need more power, but more torque, which comes from swinging a larger prop at slower speed. A normal outboard on a sailboat can actually cavitate so badly that it is completely ventilated, particularly at low speed when you gass it. Try the boat with either a much larger prop with lower pitch, or a high thrust outboard, which is designed for this application. On my Olson 30 for instance we use less than 1/4 power at all times. I have clocked it on the gps, and the speed actually goes down above this because of prop ventilation. But then I am using the wrong engine, wrong prop, BUT I know this and can make allowances.

    3) never going to happen, or at least not the way you think. Boats aren't cars and don't behave the same way. The solution to windage is to learn how the how will drift, and use it to your advantage. Plus learning how to use spring lines to control the boat. I have docked 70' boats solo, against 30kn cross winds using nothing more than the installed 30hp engine, and one spring line.

    4) outboards on sailboats should almost always be left on centerline and the boat steered with the rudder. As for size... A hundred pounds is a substantial increads in total displacement, but I guess it is at least slung low.

    5) nope hull speed won't go up, but with two props in the water, figure you will never beat 5kn. All that prop spinning is drive from the boat lost. To give you an idea PHRF gives you a credit of 12 seconds/mile for a 3 bladed fixed prop, which is the same as going to a 12 foot taller mast.

    6) a second rudder again adds weight and complexity where you don't need it. Plus you are going to double the drag of your current rudder. Figure another knot off of your speed.

    7) drop the traveller, and unroll the jib. Believe me I understand side slip, my Irwin 54' had a 5'9" keel... But we still sailed her from Miami to Venezuela.


    I am not trying to be confrontational, but I honestly think you need to upgrade your sailing skill before you worry about upgrading the boat. A lot of the problems you are describing have more to do with not knowing how to control it, than not being able too.
     
  10. buzzman
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    buzzman Senior Member

    Twin hyd drive for cat

    A mate of mine has a Crowther Spindrift 47ft cat with twin hi-pressure hyd drive motors.

    The hyd pump runs off a small 4-cyl Perkins diesel mounted on the bridgedeck at the forrard end of the cockpit abaft the bulkhead to the main bridgedeck cabin.

    Takes up very little space there and is EASY to access for servicing.

    Ditto the hyd drives take up minimal space in the aft compartment of each hull, maximising hull accommodation.

    Very low fuel consumption compared to twin motors, and was cheaper to purchase and install than twin engines.

    Works fine. But hi-pressure lines need to be swaged and attached by hyd expert....
     
  11. Steve W
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    Steve W Senior Member


    Buzzman, I realize this is an old thread but i just stumbled on it and what you describe is exactly what im looking for in a tread I just started. Do you think your friend would have a list of all the components in his hydraulic propulsion system with brands and part numbers? I would expect he does for maintainance and replacement purposes. If so do you think he would be willing to share. You can Pm me if you like. Is he satisfied with the system do you think? Did he design the system himself or have someone do it for him? Any help would be much appreciated.

    Steve.
     
  12. buzzman
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    buzzman Senior Member

    Steve
    As far as I know it was a proprietary off-the-shelf system when he installed it in the late seventies or early eighties.
    He's not so much the DIY type, but as I understand it, it needs almost no maintenance, and works brilliantly.
    Principle benefits are low weight in the aft end of the amas, compact size of drive units compared to motors, and low fuel consumption from only having the one small motor.
    Cheers
    mark
     
  13. Steve W
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    Steve W Senior Member

    Thanks Mark, does your friend still own the boat? Do you think he would be willing to get me the brands and part numbers of the components? One of the cool things about hydraulic systems is they are mostly built out of off the shelf industrial components that are used for all kinds of other purposes which keeps the cost down and ensures availability of replacement parts. I would be willing to pay a reasonable fee for a parts list of a proven system.

    Steve.
     
  14. buzzman
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    buzzman Senior Member

    Steve
    Just heard back from my mate. The motors are Volvo - F11C-19 (drive motors connected to the prop shafts). The pump is Volvo F11C-39 which is the same motor as the propulsion motors but twice the output.
    This is run off a Perkins 4108 4-cyl diesel.
    Obviously, these are now 35 years old, so whatever the equivalent is today....
    Hope that helps.
    Cheers
    Mark
     

  15. Steve W
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    Steve W Senior Member

    Mark, thank you, this is hugely helpful info as even if they are obsolete i should be able to find the specs and look for equivalent parts. I have had a brief talk with a local hydraulics rep at Air hydraulics, they can design a system but i need to supply some details such as hp and shaft rpm required, so i will pass along this info. One surprise is how large the oil reservoir may need to be, do you know how many liters your friends system uses? Is his system noisy, one of the problems im imagining is the noise from the oil passing through the lines and particularly the solid mounted drive motors telegraphing the sound through the hulls.

    Steve.
     
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