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Hydraulic Drive System


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Can a member please advise which grease to use on my boat's hydraulic system, There is a grease nipple on the final drive. The system is gear pump and vane powered by a Perkins 4108, but I do not know who the maker is, If it helps the unit with the grease nipple is blue in colour.

Many thanks

Dave T

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Nope, that looks like a grease nipple and i suspect it is a plummer block or thrust bearing as the motor appears to be bolted via its mounting flange, to a plate of some sort. Given that the tailshaft is free floating berween the stern gland and motor, ergo making no provision for thrust or radial stability, i am fairly sure thats what the plate contains.

Type of grease for that _?, i would use general purpose lithium based bearing grease, of the type used for car wheel bearings.

Hope this helps.

cheers

Trev

 

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This is a standard hydraulic drive motor (a Dowty I believe) and the grease nipple is for the thrust bearing. Notice that the motor is bolted onto a strong bulkhead glassed into the hull. This takes all of the thrust of the propellor, and is the point where the boat is being pushed along.

Use the standard grease that you would put in roller bearings.

If in doubt, ask Peachments, as I think you will find they supplied the unit.

 

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As a general information, these motors have to be properly aligned with the prop shaft when installed, if not you might "run" the thrust bearing and ruin the whole motor.

About £1200, last time I looked. If you have just bought the boat, it is worth getting this checked by a boatyard. Should take less than an hour.

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An engine linked to a Hydraulic pump can provide you with many benefits - certainly as an operator of hire boats.

First of all the engine can be placed practically anywhere, and certainly not in line with the prop shaft. Usually you will find hire boats with the engine mounted at the stern, in a transverse configuration.  Attached to the engine is the pump assemble, and a large 'header tank' for want of a better word full of hydraulic fluid.

There is no gear box, so there are less issues with 'throttle happy' hirers going from full ahead to full astern when mooring. The engine being 'out the back' keeps internal noise  and vibrations to a minimum and by further containing vibration and noise from the engine through sound insulation what you are left with is a low resonance and 'whine' of the hydraulic motor which propels the boat.

To this system you can add hydraulically powered thrustsers and, even so I believe a hydraulically powers electrical generator.  You can have canopies that open and close from this too - it can get pretty complex and the real issue is having a large enough engine that can deal with the load and pumping volume requirements of the hydraulic pump so the engine does not stall.

Sounds really great - and then there is something I don't like about them.  You see you are using a liquid to transfer torque - there is no mechanical connection between engine and propeller so you loose more efficiency.  As the pump ages, and the fluid is not changed as it should be and filters not replaced you loose further efficiency  and sometimes on boats I have hired rather  predictably, ever few minutes the pump and engine would change tone (just for a second or so) as some nasty bits fed through the pump and circulated around the system.  When you saw the deep black colour of the fluid in the tank you could imagine why.

So perhaps that shows how resilient these systems can be, but also it always costs more in fuel to travel the same distances as with a shaft driven boat.  It can be small, but in larger old boats the increase in fuel consumption can be rather significant when you have had a shaft drive boat and a hydraulic drive boat together cover the same ground and upon refueling see the hydraulically driven boat drink more fuel.

 

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This time Robin, it's you who got in first!

I agree with all you say, although it is a bit of a horror story, what you say about some old hire boats! I have never seen one like that.

Nowadays Peachment's drive installation is almost totally maintenance free. You don't need to change the oil and you change the filter every two years. It is vital, however, that if you need to top up, the oil must be fresh and totally clean. Like brake fluid, you can never re-use it.

I don't believe you lose much efficiency with the modern systems nowadays. Crown had a class of 38ft, 6 berth cruiser which used as little as 1.6 litres per hour over a week's cruising, with speed limited to 2000RPM on a Nanni 4220 engine swinging a 19X17 prop. You can't expect much better than that.

The hydraulic bow thruster is a joy, compared to electric ones. You can spend all afternoon with your finger on the button, spinning round and round like a top, and it will accept that with no problem. No overheating and no cutting out.

You can also have a hydraulic anchor or mud weight winch.

Another big advantage is that you have a soft gear change, rather than the crash of a PRM gearbox, so you do not wear out the thrust plate on the flywheel.

There are no locks on the broads but on other waterways, hydraulic drive is really the only practical way to run a hire boat.

The Peachment hydraulic generator is an excellent installation but it is very expensive to install and I would suggest that its use is limited, unless you have air conditioning on board.

By the way, you use clear oil in the system, such as Total Equivis, and not red oil. Also, you must never mix the two.

 

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Lets just say the hire boat in question is no longer in a fleet and the messy engine issue was just one of the problems such as spongy decks to walk along - but it was comfy inside and did all it was meant to so cannot complain.

I still prefer a shaft driven boat - even the most recent up to date hydraulically driven boat - Serenade - that I was on not so long ago just did not feel or sound the same as a shaft driven boat.  It is the whine of the motor perhaps, or maybe a slight disconnect between helm and engine, it was the same when using an electric drive boat you just get used to the engine note and response when you have drive plates and mechanical connections.

If I could, and owned a large power boat I'd much rather have a couple of engines on shaft than these modern IPS pod drives or stern drive systems.

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2 hours ago, Jonzo said:

Vaughan could tell you a tale or two about pod drives, I suspect...

I can't quite imagine going up the Ant on "handed" azimuth pods. I think before you got as far as Ludham bridge you would disappear up your own metacentric height!

The Voith-Schneider system might have its possibilities though. Exact control in all vectors, by GPS positioning. The perfect answer to weed cutting on Hickling Broad.

The way ahead!!  :Stinky

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I had already parted company with Le Boat before this thing was introduced, although I and other colleagues in the original management had bluntly rejected the design.

If they are are now retrofitting it then I would think they are throwing good money away after bad.

Of course, I would not like to suggest that I told them so?  B)

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We can joke about about it but it is actually very sad. Three prestigious brand names - Crown Blue Line, Connoisseur and Emerald Star, who were swallowed up in the corporate take-over procedures of tour operating yuppies.

No doubt I can tell you more about it at the spring meet!

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Grease nipple Solved

Going back  to the original post, many thanks for your advice especially Vaughan and tjd, I'm almost certain after looking on their site that the motor is a Dowty and the grease nipple is on the thrust bearing , which I will grease with confidence!

I am based in France on the Saone in the Cote D'Or. Without wishing to tempt providence my hydraulic system is smooth and quiet and cruising is very economical  on my Broads built Bounty 34 CC which has been extensively refitted over the last 2 years.

Regards DaveT

 

 

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