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Hydraulic drive system

I am interested in exploring the feasibility of a +/- 60ft long-term cruiser/liveaboard narrowboat that incorporated a transverse engine with hydraulic drive that could also power thruster(s) and a generator. Following a recent WWW article, I would like to consider the option of electric drive by using traction-type batteries to power an electric pump driving the same drive, effectively providing the option of electric or diesel running.
Can anyone suggest references that might be helpful in collecting information to assess the feasibility and costs of such a project?
Naturally I expect a cost premium, but some of this would be offset by the space gain from the transverse engine and from the lack of requirement for a seperate generator.
Any information gratefully received.

Asked by: BJM  | 2.59pm, Thursday 13 January


WW says:


The system you suggest is certainly possible, but does have some distinct cons. The advantages are mainly in the thruster department, since hydraulic thrusters are more reliable than electric ones and can be operated for much longer periods (the recommended times for 12V electric thrusters are around 2 or 3 minutes in 60).
Hydraulic drive systems are not as efficient as direct drive. There are 3 types of hydraulic system; the older CS (Constant Flow) is the simplest with a fixed rate pump where power is dependent on the engine speed, CP (Constant pressure) systems respond quicker with the engine running at a fixed speed and a variable displacement pump, and LS (Load Sensing) which is the most complicated and most efficient system. Using the hydraulics to drive a generator might dictate the type of hydraulic system as AC generators need to run at a fixed speed, but a DC generator with electronics to produce the 230V AC does not.
Adding an electric hydraulic pump to provide the option of electric drive is an interesting option, albeit an inefficient one as hydraulic systems can be as low as 50% efficient at low power settings.
A variation that could possibly improve the overall efficiency would be an electric drive to the main propeller (48V DC or 230V AC), with the power coming from batteries and/or the generator. The engine could be a dedicated generator available off the shelf, and since the hydraulic power for the thrusters would only be needed occasionally it could be a 230V electric pump. Alternatively the engine could drive the generator and an electrically clutched hydraulic pump directly.
Generally with boats, the simplest systems are often the most reliable.

Rupert Smedley  | 1.07PM, Friday 14 January

The majority of narrowbaots are bespoke, and the Hybrid Marine setup is probably a good option. A hydraulic pump could be fitted to the engine if you still want hydraulic thrusters, or 48V elctric thrusters might suit. The problem with 12V thrusters is the heat generated by the massive currents and quadrupling the voltage reduces the current by a factor of 4 (for the same power) increasing the reliability.

Rupert Smedley  | 12.02PM, Tuesday 18 January


Readers say:

Thanks for your views. All comments are helpful as I do not have the benefit of a specialist engineering background! :)
I have found the pages from the company Hybrid Marine relating to the narrowboat Chelonian, but I guess (as with cars) there are going to be a lot of ways of approaching the problem of a hybrid drive system some of which are potentially more successful, reliable and efficient than others.
If there are any readers who who have first hand experience of a hybrid system I would be very interested to hear their views. The sales literature from HM is very impressive - particularly as I had been considering a large traction battery installation anyway - their system just scales things up a little - and to 48v, which reduces the premium for their setup.
In order to be viable, I am looking for a 'standard system' rather than a 100% bespoke setup, so as to be able to benefit from the vendors sales experience.

BJM  | 3.51PM, Friday 14 January

The question that you have to answer yourself is simple - WHY do I want to go Hydraulic AND Electric. I got a quote from an "Industry Leader" in boat electic/electronics that came to nearly 76,000 pounds stg. I contacted ARS Diesels in Wakefield and found that I could get a Hydrauilic system installed for a great deal less and only marginally more than having a direct drive installed. Two things were relevant - quietness - on a narrowbaot you can locate the hydraulic diesel genny at the bows or indeed fully cocoon it.
The second was engine size - Many narrowboat engines have engine sizes of on some occasions 60hp and Barges 120 hp. Whereas in the old days becauewse of the size of the cylinders could get away with 10-20hp. With a Hydraulic systen as it is running constantly at a set revs - it produces better pressure in the hydraulics and for a lower hp of engine.
So decide WHY you want something - is it just to be different - and also - do you have heaps of money to throw at a project that outwardly does nothing for you but give bragging rights???.

PAUL BROWNETT  | 10.57PM, Wednesday 19 January

Thanks. My main interests were a) the ability to mount the engine transversely, b) the ability to use the same engine for a powerful generator rather than a seperate generator and c)that once a hydraulic system was available it could be used to power thruster(s) rather than electric units.
The ability to store excess engine power when using the diesel (as claimed by Hybrid Marine) would/should also indicate fuel savings. However, I had not appreciated the amount of power loss with hydraulic drive or indeed that they were (quite so) exquisitely expensive.

BJM  | 10.42AM, Thursday 20 January

I would hate to think who you have been talking to - it cant have been ARS Diesel - the quote for my Widebeam with a bowthruster was under 14K including the thruster. It is a short step to adding a genny to one of these systems.
My quote from Mastervolt to go electric - admittedly with "podthrusters" was over 72,000.
With ARS - you can park the engine anywhere including the bows - and if you look at the cost of a normal drive engine plus a decent bowthruster then you are not far off the ARS pricing.
If you look at the overall losses on direct drive engines then (and I am not an engineer) the huge 50 or 60hp engine you are using can only put about 4hp into the canal without upsetting everyone.
With hydraulic you can have quiet sensible narrowboating and it doesw not cost that much more. I was a huge electric fan and even resourced info from the USA - not any more - hydraulic is the only way for me.

PAUL BROWNETT  | 3.25AM, Sunday 30 January

Thanks Paul,
ARS Diesel has been the latests discovery on my web browsing, so I am going to contact them for a bit more detail than I can get from their website.
I am certainly impressed by the flexibility of the hydraulic configuration, and assuming someone has resolved the problem of engineering comparable efficiency at an affordable cost I am definitely interested.
The reason for being very interested in the feasibility of the electric option being incorporated is that I mad been anticipating a large 'house battery' based on traction cells anyway (to meet out living requirements), and the H-M system is based around an (up to) 805 ah 48ah bank. This is an integral part of the H-M system, whereas addinganything substantial to a standard setup would immediately be very expensive. Thanks for taking the time to add your comments.

BJM  | 10.54AM, Sunday 30 January

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