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davidruddy

propulsion problems

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I am new to this boating lark so I thought I would ask here before i bite the bullet and approach my nearest boatyard.

 

I have a 50 foot narrowboat built 2001 - it has a 2 cylinder air cooled engine and a hydraulic drive. Within a few weeks of having bought it I experienced a fall off in the speed the boat would go - no matter how much i increased the engine revs - it ended up with te filter on the hydraulic drive blowing out/sprung a leak - with the drive in gear it blew hydraulic fluid all over the engine room. Anyway, the guys from canal river rescue eventually got me a replacement filter and fitted it and all seemed fine......five months on and having probably run the boat for i guess around 100 hours of cruising I now have a new problem.....I have started to experience the same fall off of forward propulsion and as i was about 10 minutes from my home marina I limped back to base. I found that by putting it into reverse for a few seconds and then back into forward gear it chugged along quite happily but then gradually slowed right down again. Putting it back into reverse and then forward meant I could limp along and eventually get home.

 

Does any bright spark out there know immediately what my problem is and how best to solve it ? I am guessing I have some foreign objects (rust maybe from the metal expansion tank for the hydraulic fluid ?) floating around which some how the filter cant cope with and its just preventing any meaningful forward propulsion. I am no engineer and am loath to start disconnecting hoses off my own bat in case i cause more problems than i fix! but is it likely to be something as simple as just a bit of rubbish in the system or am i looking at mega bucks and new drive system ?

 

Apologies if the answer is obvious and is just get it down to an engineer in a boatyard! I thought I would just ask in case there is something I can do to solve it easily.

 

Thanks in advance for any helpful suggestions and sorry if I have wasted anyones time wading through my longwinded story. If there is any thing ive left out and you need more info then please let me know. Waiting replies with trepidation......... 

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sorry forgot to say I have had the weed hatch off and checked the prop is clear - lovely job in freezing cold water. the rpop does move around with no obvious noise

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Doex the engine make black smoke when you are struggling to get drive?

Have you checked the prop is clear?

Is the water full of part floating leaves?  A bladeful of leaves gives the symptoms you describe, and as soon as you stop to dive the weedhatch they all drop off, only to cluster up again once you engage  forward.

If that is both OK, check the fluid levels in the hydraulics and change the hydraulic filter.

N

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Welcome to the forum.

Autumn in to winter leaves collecting round the prop will give these symptoms. The leaves shield the prop and prevent it getting any bite on the water. You slow down, increase revs, nothing happens. A quick blast of reverse every so often clears them. If you take the weed hatch cover off and have a feel around there is nothing there as you had to use reverse to stop. Start again and the prop starts collecting leaves again. Just keep giving a short burst of reverse as soon as you feel the speed start to drop. It will go away later in the winter through to next autumn.

 

Fallen leaves. Not just a problem for trains.

 

Jen

16 minutes ago, davidruddy said:

I have started to experience the same fall off of forward propulsion and as i was about 10 minutes from my home marina I limped back to base. I found that by putting it into reverse for a few seconds and then back into forward gear it chugged along quite happily but then gradually slowed right down again. Putting it back into reverse and then forward meant I could limp along and eventually get home.

 

Edited by Jen-in-Wellies
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39 minutes ago, zenataomm said:

Make and model of both your engine and the gearbox might help a bit.

It’s a hydraulic drive. 

56 minutes ago, davidruddy said:

it ended up with te filter on the hydraulic drive blowing out/sprung a leak

Was that because the filter was clogged?  As you have the same symptoms have you changed the filter? Or at least checked it for gunge?

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Same symptons - could be same problem. The filter should not be hard to get hold of, agricultural dealers, plant engineers, hydraulic place, e.g. Pirtek  or even a car spares place. I would start with that. Blowing a filter off? Blimey, that's some pressure. Hydraulics are not my speciality but I would think a pressure relief valve should be in the system somewhere. I think if I were you I would speak to someone who knows about these things, could even be engine oil in the thing and not hydraulic fluid.

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With a conventional drive when the prop is overloaded or fouled, provided the gearbox is not slipping, the engine will not speed up and you will get black smoke but in a hydraulic drive excess loading on the pump could open the relief valve allowing the engine to rev and cutting power to the prop , as you slow down the relief vave will close again and you will get back some drive. I am not sure why this would cause the filter to blow abut it depends on the set up and how the filter is positioned in the hydraulic circuit. If the PRV is set too low this would happen but if set too high and the propeller hits something you may cause damage to the system or burst a pipe.

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2 hours ago, davidruddy said:

 

Apologies if the answer is obvious and is just get it down to an engineer in a boatyard!

 

I think you may find that the average boatyard engineer has no knowledge of hydraulic propulsion systems, so will be unable to help, or worse blunders around blindly, possibly making matters worse.

Edited by David Mack

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Check your hoses.  I used to do hydraulic hose failure analysis for BTR/Dunlop many years ago.

 

When hydraulic hoses start to fail, you often get a flap of the inner liner start to lift in the direction of flow.  This reduces oil flow significantly and would cause the symptoms you are seeing.

 

From a boaty point of view, so would a leafball round the prop as suggested by @Jen-in-Wellies earlier ... I have had my boat completely stop in the water due to too many leaves.

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Assuming it's not leaves etc.  you need to get your hydraulic system looked at by an expert.  I recently had a qualified engineer service our hydraulic drive.  It involved connecting the hoses to a sophisticated piece of computerised diagnostic kit.  It confirmed that ours was working perfectly with a pressure of 5000 psi and shifting a volume of 28 litres a minute. The relief valve blow pressure was also checked.

If yours is an ARS drive, then the man to call is Martin Bullock at ARS Anglian Diesels Limited  01924 332492.

It will not be cheap, but then with those pressures I don't think you can afford to cut corners.

 

I also replace the hoses, change the filter and fluid periodically - again not cheap.  

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19 hours ago, davidruddy said:

sorry forgot to say I have had the weed hatch off and checked the prop is clear - lovely job in freezing cold water. the rpop does move around with no obvious noise

 

I can't help diagnose yiur hydraulic problem, but pouring a kettlefillor two of boiling water down the weedhatch before putting your hands down there takes the chill off the water.

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