Electric or Hydraulic propulsion system for small boats

[jedclampit]

Hey all,

Has anyone seen or heard of such a propulsion system for small boats?

I have this concept for the propulsion of a sailboat based on the current technology utilized on the worlds largest cruise ships. They use large electric motors in pods hanging under the hull with direct drive or geared propellers. They have two pods that are fixed and two pods that are independently steer able. (I’m not sure if this (pods) is the proper terminology.) These electric engines are powered by large onboard diesel generators which also provide power to the ship.

What if you build a system that has an electric or hydraulic motor encased in a unit that attaches to the transom behind the rudder and then lowers down into a fixed position for motoring?

At first I thought of putting the engine in a pod like a huge trolling motor and lowering it into the water…Kind of old-school. This could be run off the house generator or if hydraulically powered then you could have a pump off the house generator that would power the unit. Either way you would have just one power source that would charge the house batteries, run appliances and propel the boat.

Then I thought that maybe it should have a fixed motor on the transom that would have a shaft that could move (slide) up and down to lower the propeller pod driven by a gear (turning vertical rotation into horizontal rotation). I though about maybe using a enclosed jet drive like a jet ski or a Jacuzzi drive that would encase the prop therefore making it more efficient and easier to house when retracted back up into it’s transom mount.

Anyway I like the idea of no thru hull connections…the electric or hydraulic component and the retract ability of the concept.

Any input?

[dsharp]

It's called an azipod. Never seen one on a small boat although you may could convert something like a bowthruster, it has a similar design. Vetus makes them in electric and hydraulic. I think the problem with electric would be the size of the motor required to put out enough power.

[jedclampit]

Yes that is what I was thinking…the bow thruster concept. Sailboats only require small amounts of power…thus a larger boat’s bow thruster might be the ticket. I was thinking for boats under 10 meters…or 30 feet. Approximate size would be 40 hp.

I guess that the trade off would be the extra weight of the electric motor and the electrical alternator. And of course there is the additional maintenance of the three components vs. just the engine in a typical drive train system.

Maybe the Hydraulic systems might weight less. I’ll have to look for some components to see what the actual weight would be. I know a mechanic who built an off road truck with hydraulic motors at the axles and drove them off a pump on a diesel engine. Top speed was low but the thing would climb a tree.

[jedclampit]

Thanks for the line on Vetus...they do in fact have a hydraulic system that could be modified or incorporated into my original concept. Now I need to find out cost... Weight seams not to be the issue.

There seams to be many benefits to the hydraulic system as well; propulsion, anchor windlass, bow thrusters, outdrive lift (my concept) and my favorite idea was to use a hydraulic ram to raise and lower the mast… I guess that you could also make a heavy pop top by raising the roof of the cabin with rams… and all these can be run (one at a time) without any problems…

I kind of like that idea. Maybe a small alternator could be run off the main engine to charge batteries and run appliances as well…

Cool, I’ll keep researching! Thanks again...

Here is the link: http://www.vetus.nl/indexns.asp?lang=2&productid=19

Hydraulic marine propulsion

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In a number of cases it may be highly recommendable to drive the propeller shaft by means of a hydraulic motor, instead of by the conventional in-line arrangement of engine and gearbox.
One of the major advantages of hydraulic propulsion is the fact that there is absolutely no need to position the engine in line with the propeller shaft.
As a matter of fact, the engine may be positioned in any place, deemed convenient, even athwartships.
In the case of the propeller becoming jammed on rocks or in the mud, there is virtually no risk of damage for the shaft assembly, the hydraulic motor or the main engine itself, as an integrated by-pass valve will then eliminate any force which the hydraulic motor may exercise on the shaft assembly.
Especially in the case of hire craft, this has clearly been established as a great advantage. The hydraulic motor is engaged in a smooth and noiseless manner.
The assembly as such operates completely free of vibrations and the thrust of the propeller is not transmitted to the propulsion engine, but to the hydraulic motor, which is flexibly mounted on its own bed.

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HOW IT ALL WORKS

A hydraulic vane pump (4) is fitted to the engine in the place of the gearbox.
This pump (4) draws its hydraulic fluid from a storage tank (3) with integrated oil cooler and presses the fluid into a hand-operated steering and controlling valve (2).
From this valve, the oil flux is directed, left or right, to a hydraulic vane motor (1).
This hydraulic pump drives the propeller shaft directly. The VETUS system uses hydraulic pumps and motors with a fixed swept volume. The transmission ratio is
constituted by the difference in swept volume of the vane pump and the hydraulic motor. The reduction of the number of revolutions of the marine engine to the number of revs. at the shaft is set at 1,9 : 1.
The maximum revs. of the main engine must be set at 3.000 r.p.m.
The maximum engine power amounts to 50 kW, meaning that a shaft diameter of ø 25 mm will be sufficient in most cases. The outgoing flange of the VETUS hydraulic motor fits all VETUS flexible couplings.

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One of the mechanical VETUS Stainless steel VETUS
remote controls, hydraulic storage tank. hydraulic vane
will regulate shaft vane motor pump
speed and direction
of rotation.


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Scope of Supply
VETUS hydraulic propulsion is available in 3 versions:

Model HPM 4.15 Model HPM 4.17 Model HPH 4.65
is suitable for is suitable for is suitable for
engines up to engines up to engines up to
24,3 kW (33 hp). 33.9 kW (42 hp). 48 kW (65.3 hp).
- A hydraulic vane - A hydraulic vane - A hydraulic vane
pump pump pump
- A hydraulic vane - A hydraulic vane - A hydraulic vane
motor motor motor
- A control valve - A control valve - A control valve
- A storage tank - A storage tank - A storage tank
- An oil cooler - An oil cooler - An oil cooler

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1. Hydraulic motor
2. Hand-operated
control unit
3. Stainless steel
storage tank with
integrated oil cooler
4. Hydraulic pump
5. Remote control
for the engine
6. Connection for sub-3
drives
7. Control unit for sub-drives
8. Bow thruster
9. Anchor windlass

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Code Description Export price in euro
Excl. VAT

HYDRAULIC PROPULSION





HP/kW Max RPM Reduction




HPM4.15
33/24.3 3000 2,0:1
Prices on request
HPM4.17
42/30.9 3000 2,0:1
Prices on request
HPH4.65
65.3/48 3000 1,9:1
Prices on request




STANDARD SPECIFICATION INCLUDES: Marine diesel engine suitable for hydraulic propulsion including hydraulic vane pump, s/s 35 litre hydraulic oil tank and hydraulic motor for propeller shaft propulsion. The diesel engine will be supplied with four flexible engine mounts and MP22 instrument panel.

[Oyster]

http://www.ev-america.com/

These folks are like an encyclopedia for electric drive train. Take some time and swap a couple of mails with them, You would be surprised how economical a package is for a 30 footer or less sailboat or even a launch type hull..

[jedclampit]

Great Idea Oyster...Thanks I will send them an email today...

Thanks again, and I hope there's no hard feelings? I didn't want to upset anyone.

Jed.

[Oyster]

No problem here. Sawing up new boats, or reading about it, is like scratching fingernails on a blackboard for me, though. We are have to half cracked anyway for being in this crazy addiction. You will find that I am worse than an enviromentalist when it comes to even one extinction of a species, such a hull as the one represented in your previous posting. The course of least resistance is only temporary for the mind, but will sometimes haunt you down the road. WHile there are times to do so, I am not sure if that fits your situation, from afar, anyway. Nice for me to say that, I guess, since its not my money. Smiles and Cheers

[robbieroneill]

Volvo has been making drives and pumps since the 70's for small boats (-15m)

[Guillermo]

Jed,
Maybe you would like to investigate on RIM trhusters:
http://www.brunvoll.no/Web/resources.nsf/0/0F5A219AA75C9EC4C1257083002E22F7/$FILE/Brunvoll_developes_RDT.pdf

[jedclampit]

Jed,
Maybe you would like to investigate on RIM trhusters:
http://www.brunvoll.no/Web/resources.nsf/0/0F5A219AA75C9EC4C1257083002E22F7/$FILE/Brunvoll_developes_RDT.pdf

I do like the Azimuth Thrusters. Very cool idea. The retractable concept is very appealing for the motor sailor or sailboat. I don’t think that steering capability is necessary, but would be a nice luxury when docking.

I also like the concept of the rim drive, however I think this also would be great if it was Hydraulic powered. I am of the opinion that I will be using a hydraulic powered system for the benefit of other needs aboard.

I don’t like the uncertainty of the design being such a departure from the norm that you could not find a local mechanic to aid in repairs when you are in remote areas of the world.

Thanks for the link…

I will write them to see what a small 40-60hp system would cost.

[DanishBagger]

I know it's not podlike, but have you checked out solomon technologies?

As a little side-note, being electric (having torque all the way from the bottom of rpms) much less horsepowers are needed. So if you go ask for a "40-60hp", then go ask for "the equivalent to a 40-60hp diesel/gas engine". That way you won't have it overpowered and it won't weigh too much.

Maybe even ask on of those trolling-outboard manufacturers if they can make the drive itself larger, fitting your demands.

Btw, there's an old, HUGE thread where solomon's "eletric wheel" is discussed, right here on this forum.

[FAST FRED]

What advantage do you hope to gain with the extra complexity of this , compared to a shaft ?

The cruise shjips can handle any expense as their pods will drive them 3 1/2K sideways (NO EXPENSIVE TUGBOATS) while docking.

The hotel and push loads vary by a large order of magnitude , so 3 to 15 generators are used as needed, the gensets can be properly loaded and secured when the load becomes too light.

Depending on the HP required an outboard leg that can spin the desired diameter prop can easily be coupled to a hyd motor.

But the efficency will be at least 20% worse (high fuel burn) and perhaps weight as compared to a common shaft & prop.

FAST FRED

[robbieroneill]

See http://www.whisperprop.de/ for the small boat azipod data.
This is agreat system for small boats (-15m)
I am building a boat for European Canals and rivers see www.robandmarlane.com
Problem: a 25 ton boat with a 100hp diesel on a 2:1 gearbox turning a 60cm x60cm prop is the boat goes 5kph at idle. That is the maximum speed limit on the canals in southern France. While navigating shallow twisty canal at idle, the motor gunks up, the alternators don't charge well and it is a constant shifting from fwd to N. to rev and back to fwd again. One needs the 100 hp. power to navigat rivers and coastal cruising.
So how to go slow? The Diesel Electric solution with two gensets; a small unit 15kw and a large 35kw on the same grid to turn a 50kw azipod w/60x60cm prop. Use the small generator to go slow and both or the large to go fast easy enough. But the Domestic AC/DC ring is another problem. The Azipod uses 430vdc, how to convert to 12vdc or 220ac 50hz.? for 30amp domestic power? Fischer-Panda says buy another Genset for domestic power! I don't think this is the best solution, but they do sell generators as a primary business don't they. Got any ideas?

[brian eiland]

...I am building a boat for European Canals and rivers see www.robandmarlane.com
Problem: a 25 ton boat with a 100hp diesel on a 2:1 gearbox turning a 60cm x60cm prop is the boat goes 5kph at idle. That is the maximum speed limit on the canals in southern France. While navigating shallow twisty canal at idle, the motor gunks up, the alternators don't charge well and it is a constant shifting from fwd to N. to rev and back to fwd again. One needs the 100 hp. power to navigat rivers and coastal cruising.
So how to go slow? The Diesel Electric solution with two gensets; a small unit 15kw and a large 35kw on the same grid to turn a 50kw azipod w/60x60cm prop. Use the small generator to go slow and both or the large to go fast easy enough. But the Domestic AC/DC ring is another problem. The Azipod uses 430vdc, how to convert to 12vdc or 220ac 50hz.? for 30amp domestic power? Fischer-Panda says buy another Genset for domestic power! I don't think this is the best solution, but they do sell generators as a primary business don't they. Got any ideas?
Hello Robbi. I might suggest you utilize the "search" function key on this forum and look up "diesel-electric". You will come up with lots of info on a great number of subject threads.

Here are a few I might recommend:
http://boatdesign.net/forums/showthread.php?t=9310 (http://boatdesign.net/forums/showthread.php?t=9310&highlight=diesel-electric)
http://boatdesign.net/forums/showthread.php?t=9630 (http://boatdesign.net/forums/showthread.php?t=9630&highlight=diesel-electric)
http://boatdesign.net/forums/showthread.php?t=676 (http://boatdesign.net/forums/showthread.php?t=676&highlight=diesel-electric)

try this reference also http://boatdesign.net/forums/showpost.php?p=44393&postcount=2

Sorry, a little short on time at the moment, but I do believe this is THE IDEAL solution for your utilization.

I do need to keep in touch with your website as I have always dreamed of doing a trip thru France on a canal boat with a bicycle for short side excursions.

[jedclampit]

FAST FRED,

As to reasons to opt for hydraulic power over electric, as you know alternators and electric motors are not efficient (at best 80% both generating and powering) and the weights of units in the 40 to 100 hp range are quite large.

I need hydraulic power for other applications onboard and the weights of the motors and pumps are not extravagant therefore I think that this is my best solution.

Hydraulic motors and systems are light weight and cheep. As an example a twenty horse power motor weighs less than 20 pounds and is under $500. Locating a spare on board is not a problem; however a twenty horse power electrical motor weighs about 800 pounds and is well over three grand. A complete hydraulic system with a complete backup system is less weight and less cost than a single electrical drivetrane system.

I also want redundant systems and hydraulic components can be ganged and valved (backups) and easily modified on the fly if there is a need, however if you should kill the alternator in a diesel-electric system, there is no way to get power without having a very very long cord.

I am planning on having a secondary hydraulic pump or system on a smaller diesel genset that could provide enough power for minimum propulsion and the other systems if the main system should fail. This smaller system will be utilized while offshore under sail or moored and propulsion is not required.

Also the main power plant will have a small alternator that will provide dc for the house panel and for battery charging thus two redundant systems without a lot of excessive weight.

Jed.

[jedclampit]

thanks for the links Brian...

[robbieroneill]

Indeed some of the the electrical pieces are big nut parts could more readily available that you choice of hyraulics. I had a vovlo system in the Carribean and ended up waiting several weeks for parts from Miami. In a sail boat config. There is an electric-generator drive unit that works both ways, it charges your bateries while you sail. and propells you with a genset. Nice if can sail a lot. The biggest cost I encountered with my Hydraulics was the cost to replace hoses, they ain't cheap and rare as hens teeth in the 3rd. world. You can get wire and amatures rewound just about anywhere.
You plan for a long haul ocean voyage, get the most of the spares you can afford and when it is all said and done,you get home with a bunch of rusty spares. See my site www.robandmarlane.com

[Guillermo]

I've found this 20 kW electric pod (Sail drive) from Germany, seeming able to go up to 30 kW:
http://www.kraeutler.at/SD%2020kW_e.htm
They have a wide range of electric propulsion systems for boats.

[FAST FRED]

"You can get wire and amatures rewound just about anywhere."

Perhaps , but the electronic controlls are going to come from a single source who KNOWS he has "Got YA!"

Hyd is really competative worldwide spairs are easy to purchase and carry and other brands can always be substituted.

So all thats left against Hyd is "efficency" and cost (compared to cheap std drive).

For a canal cruiser that needs maybe 6 hp to go 6mph , the cost of producing 8hp should not be much of a problem , even though system efficency might "only" be 75%.

The use of Hyd to operate other gear aboard easily compensates .
When an electric winch or bow thruster is overused , smoke comes out .
When hyd is overloaded it just stops till the load is reduced.

FAST FRED

[StianM]

The controls are not mutch off a problem, a good electician can normaly fitt controls from another manufacturer with no problem.

Moust controls today follow standards off 4-20mA or 0-5V unless it's digital.

[robbieroneill]

All of this stuff is availble online via fed ex or dhl. The controls are the most reliable part.

[DanishBagger]

Robbie,

Indeed, most stuff is available online, but you can't find it if you don't know where to look. Plus, and this is the important aspect, getting real life opinion instead of marketing hype is pretty important. After all, this is a discussion forum, and other people's opinions are rather important (at least in my opinion).

Why don't you post some of that online content, and give your opinion on it, see if you can find "The shizzle" (lol) for the thread starter. And perhaps share your opinion with us.

Andre

EDIT:

P.S. What does DHL and Fed Ex have to do with anything? They just ship it if you pay them. The only product they sell is a service to deliver whatever you want to send.

[FAST FRED]

The efficent motors have computers that know where the rotor is at all times and vary the pulse to vary the power.

Not sure someone elses controlls would work , but I'm not an electrican..

FAST FRED

[marshmat]

Fred- I've used NGM three-phase BLDC controllers of the type you describe, and will soon be dealing with a Tritium WaveSculptor of similar output characteristics. Great machines, but really pricey - A 5 kW BLDC controller is worth around $4,000 to $6,000 CDN (granted, the things are 97-98% efficient).
Generally, most controllers designed for the motor architecture you are using can be used, regardless of manufacturer, provided that waveforms, impedances, inductance ratings, and all those other technical parameters are fairly close to ideal values.

[FAST FRED]

A 5 kW BLDC controller is worth around $4,000 to $6,000 CDN (granted, the things are 97-98% efficient).

While not as "efficent" the entire hyd SYSTEM would cost less than a single controller.

FAST FRED

[robbieroneill]

Bagger
I'm a sailor, it is a matter of function and reliability rather than theory and Blah, Blah. If you don't know where and how to get parts for your boat -Don't go to sea. Obviously you have not or had your boat break down in some little corner of France or the Turks and Caicos. My catamaran had a twin volvo HD drive, the pump popped 8 weeks later it was working again.

Everything will fail at sea. How easy it is for YOU! to repair and how readily the parts are is very important. All of that media hype on line also tells one of distribution and reliability. www.whisperprop.de These guys are on the right track. D-E power is ideal for the live aboard, one motor supplies energy to all systems. One set of spare parts. The weakest link to all electrical applications marine and otherwise is energy storage. The battery technology is the weakest link. How about that for opinion?

[marshmat]

A 5 kW BLDC controller is worth around $4,000 to $6,000 CDN (granted, the things are 97-98% efficient).
While not as "efficent" the entire hyd SYSTEM would cost less than a single controller.
FAST FRED
If you're going for top-end high efficiency electrics, this is certainly true.
If you can tolerate 80% efficient electrics, though, the cost comes down an order of magnitude. Yes, the hydraulics will probably be cheaper, but I think I come out in favour of electric here. Of course, for overall best efficiency one would use a plain shaft drive.
EDIT:
If anyone's interested in the latest generation of motor controllers.... http://www.tritium.com.au/project/project.html , Tritium's 30 kW WaveSculptor is due to be released shortly.

[DanishBagger]

Bagger
I'm a sailor, it is a matter of function and reliability rather than theory and Blah, Blah. If you don't know where and how to get parts for your boat -Don't go to sea. Obviously you have not or had your boat break down in some little corner of France or the Turks and Caicos. My catamaran had a twin volvo HD drive, the pump popped 8 weeks later it was working again.

Everything will fail at sea. How easy it is for YOU! to repair and how readily the parts are is very important. All of that media hype on line also tells one of distribution and reliability. www.whisperprop.de These guys are on the right track. D-E power is ideal for the live aboard, one motor supplies energy to all systems. One set of spare parts. The weakest link to all electrical applications marine and otherwise is energy storage. The battery technology is the weakest link. How about that for opinion?

Yup, good to have an opinion, although I could do without your assumptions about me.

However, what I was commenting on was you going "Everything is online, you can get it through DHL" or something to that end. Now, that is not advice, imo, that is just stating the obvious. Yes, nowadays, what can't be found online? That was my whole point. And, like you just said, getting parts is indeed important, and also a reason for keeping things simple. I fully agree (and am still pissed about your assumptions about me).