The Pro's and Con's of Hydraulic Drives

[cheshire~rose]

I am starting the topic on the basis that I know nothing about Hydraulic drives so please be gentle

 

I am working with a team of volunteers trying to pull together a specification for a new build trip boat. The boat will replace one that has been in service for more than a couple of decades and it is fair to say that some of those volunteers have been part of that team for the lifetime of the boat - but have little or no experience of other boats at all. The team in question know their own boat (and their own stretch of canal) really well. The current boat has a hydraulic drive and so that is what they are all used to.

 

Because I am not personally very familiar with the boat I was unaware that it had a hydraulic drive and so when the subject popped up in discussion with a boat builder and they suggested that it would (understandably) add cost to the build I have started to ask myself questions about why a hydraulic drive might be needed. I don't have the answers so over to you experts on here to help explain this to me, and a group of people who don't necessarily understand any other boats than the one they have been using for the last couple of decades.

 

My understanding is that a hydraulic drive is useful when you want to house your engine somewhere other that directly in front of the prop. In this case that does not apply. Is there any other reason why you might choose to fit one?

 

Am I also correct in thinking that we may need a slightly larger engine to power a hydraulic drive?

 

Are hydraulic drives more "robust" when gear changes are handled by trainee crew? If someone has spent the last 20 years driving a boat with a hydraulic drive might they have difficulty in adapting their driving style to that required of a normal gearbox?

 

 

Please enlighten me folks. Thanks

 

 

[by'eck]

Surprised you haven't seen this thread. Range of views but little doubt its more expensive than conventional direct drive.

[Ray T]

There is an article in September Canal Boat of a boat with hydraulic drive, page 28.

 

Koukouvagia has one on his butty.

Edited August 6, 2015 by Ray T

[MtB]

Main benefit: Put the engine anywhere you like, if the conventional place is awkward

 

Main drawback: Adds £5k to £10k to the cost.

[koukouvagia]

 

 

Am I also correct in thinking that we may need a slightly larger engine to power a hydraulic drive?

 

Are hydraulic drives more "robust" when gear changes are handled by trainee crew? If someone has spent the last 20 years driving a boat with a hydraulic drive might they have difficulty in adapting their driving style to that required of a normal gearbox?

 

 

 

 

The thread mentioned by Richard is a good starting point.

 

We've got a 1.8 BMC with an hydraulic drive on the butty. It's perfectly OK for a 72' 25 ton boat.

To be honest there's not much difference from the steerer's point of view. I doubt whether anyone would notice the difference.

It's vitally important to get an expert firm to specify the system. We used ARS Anglian diesels.

 

I know you are a long way away from Tring, but if you ever wanted to see how an hydraulic system works, PM me, I'd be happy to show you.

[cheshire~rose]

Thanks everyone, indeed that other thread does have a lot of information to help weigh it all up and I don't feel you need to be an engineer to understand it.

 

Huge help thanks

[magnetman]

Some boats use hydraulic drive so that the engine can be right at the back under a service hatch leaving the full cabin length for full height accomodation. This would be for a boat without a wheelhouse and forward steering probably. The old fibreglass "slug" boats like the Caribbean broads cruiser had this design and successfully maximised interior accomodation space.

 

Another possible option to maximise interior space is a raised engine with belt drive to turn the shaft immediately below it.

Another reason may be that the boat did not have a conventional swim and required some sort of pod drive or similar which could not be driven by gearbox and shaft.

 

I think the internal space argument is the most compelling specially for a passenger boat.

Edited August 6, 2015 by magnetman

[Murflynn]

 

 

To be honest there's not much difference from the steerer's point of view. I doubt whether anyone would notice the difference.

 

.............. in this case, really that is what it's all about, isn't it?

[cheshire~rose]

.............. in this case, really that is what it's all about, isn't it?

 

Yes that is my main concern. To persuade a group of individuals to embrace change can be a challenge but if we know that there are a lot of positive reasons to change and no negative ones it makes it much easier to "sell"

 

The rear deck is a cruiser style so there is plenty of room but we might still be juggling with where the wheelchair lift goes ........... so many decisions.....!

[billh]

Hydraulic drive is more robust. If you are on a rubbish strewn canal and the prop fouls ,say a log stuck in it , a pressure relief valve opens and the shaft,couplings and prop are protected from damage. Also, forward to reverse can be done at full engine power as again any surge is absorbed by the PRV, the engine doesn't notice. All very useful for a tug, workboat or dredger( where the hydraulics are there anyway for the dredging bits).On a passenger boat, novice steerers won't damage anything with rapid F-N-R operation,perhaps that was why the original boat was so equipped?

Bill

[mattlad]

One other advantage that comes to mind is that on a lot of hydraulic systems there is no stern gland issues to worry about.

 

One disadvantage is that they are not as efficient and fuel consumption will be higher.

[Alan de Enfield]

We hired a boat - it had a hydraulic drive and on asking "why" was told it meant that the engine could be mounted transverse making a couple of feet extra space for the cabin.

 

If space is not critical is it worth the extra £'s ?

[FadeToScarlet]

Have you thought of electric drive, with a cocooned genny? Could be quieter for the passengers, engine can be anywhere, same fwd-reverse switching, bow thruster etc., easier to charge, and then there's plenty of 240v on tap for things like Burco boilers for tea and coffee, wheelchair lifts, PA systems, etc.

[larkshall]

Yes that is my main concern. To persuade a group of individuals to embrace change can be a challenge but if we know that there are a lot of positive reasons to change and no negative ones it makes it much easier to "sell"

 

The rear deck is a cruiser style so there is plenty of room but we might still be juggling with where the wheelchair lift goes ........... so many decisions.....!

Wheelchair lifts are awkward, it is in fact a reason to go hydraulic for the drive. It completely frees you to decide on where you want the lift, then all other bits can fit anywhere around the lift. Of course hydraulic power means you could easily install, hydraulic generator, bow thruster, and maybe power the wheelchair lift. In your particular circumstances don't dismiss it without a full costing, including design.

[cheshire~rose]

Thanks everyone.

 

The canal has very little rubbish in it at all - although weed is another problem entirely (at certain times of year)

 

The origins of the plan for the boat we have has been lost in time. No one is actually too certain who built it! I think that is what happens when a boat is owned by an organisation run by volunteers. I think many of the people who would have been involved with the build of the boat are no longer with us now. We don't know why it has a hydraulic drive. It does have a "normal" stern gland though that needs greasing

 

 

Have you thought of electric drive, with a cocooned genny? Could be quieter for the passengers, engine can be anywhere, same fwd-reverse switching, bow thruster etc., easier to charge, and then there's plenty of 240v on tap for things like Burco boilers for tea and coffee, wheelchair lifts, PA systems, etc.

 

 

Oh let's not go there please. They already have one trip boat that is a hybrid - it is a wonderful idea - when it all works... but has caused so many headaches one thing that was cut and dried in the spec for this boat was that it would be a straightforward design.

Wheelchair lifts are awkward, it is in fact a reason to go hydraulic for the drive. It completely frees you to decide on where you want the lift, then all other bits can fit anywhere around the lift. Of course hydraulic power means you could easily install, hydraulic generator, bow thruster, and maybe power the wheelchair lift. In your particular circumstances don't dismiss it without a full costing, including design.

 

That is an interesting thought. who would be able to design that sort of system?

[larkshall]

Designer? The one I know of with a good reputation, is ARS ANGLIAN DIESELS. Someone on this forum has used them, my experience of them comes via friends who converted a boat as one of then has MS.

[Timleech]

Wheelchair lifts are awkward, it is in fact a reason to go hydraulic for the drive. It completely frees you to decide on where you want the lift, then all other bits can fit anywhere around the lift. Of course hydraulic power means you could easily install, hydraulic generator, bow thruster, and maybe power the wheelchair lift. In your particular circumstances don't dismiss it without a full costing, including design.

 

Not necessarily so. It does depend on what the design is of the main propulsion system. Mine is a closed loop system which doesn't permit add-ons in such a simple manner. I did include provision for an extra small pump to drive auxiliaries, but have never had the need to fit one.

 

Tim

Edited August 7, 2015 by Timleech

[Heffalump]

Have you thought of electric drive, with a cocooned genny? Could be quieter for the passengers, engine can be anywhere, same fwd-reverse switching, bow thruster etc., easier to charge, and then there's plenty of 240v on tap for things like Burco boilers for tea and coffee, wheelchair lifts, PA systems, etc.

 

I can't give you a greenie but I really like this idea.

[David Mack]

Oh let's not go there please. They already have one trip boat that is a hybrid - it is a wonderful idea - when it all works... but has caused so many headaches one thing that was cut and dried in the spec for this boat was that it would be a straightforward design.

 

If a straightforward design is what you want, then why are you considering hydraulics at all? A conventional diesel engine and gearbox will be the cheapest to build, operate and maintain.

[cheshire~rose]

 

If a straightforward design is what you want, then why are you considering hydraulics at all? A conventional diesel engine and gearbox will be the cheapest to build, operate and maintain.

 

That is exactly why I asked the question here. I needed to understand the pro's and con's of something I didn't understand. As a broad generalisation: The current crew only know hydraulic drive because that is the only boat they have ever steered. Therefore they "think" they want a hydraulic drive.

If the crew are properly informed about the differences between the two systems and understand the differences it can make to the initial cost of the build and long term cost then it is easier for them to accept that not ALL change is a bad thing.

 

I can rely on this forum to explain things in a way that can be understood by people who do not have a degree in engineering and you have done that admirably again thank you very much.