Sizing electric motors

[ted655]

As an example, I include this boat.
1. What size EMs would one install, (roughly)? 1 for each side wheel.
2. Would they be DC or AC/ Single-three phase?
3. Gearboxes or sprocket ratio ed?
A paddle wheeler seems like a good canadate, allowing for a cleaner/safer engine room.
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If a boat this size was to be converted, & the side wheels were to be used to actually propell it, where does a guy start in trying to learn hybred systems.
I see this type of propulsion as the now/future.
I'm just curious about practical types & sizes of the equipment, that will be needed :)

[alan white]

I think the principal advantage of a hybrid system on such a boat is that the paddles are easily turned whenever it's anchored in a river current. The hybrid boat can be compared with a hybrid car used only at highway speeds, or at least constant cruising speeds.
In fact, no electric system is really needed by a hybrid car at cruising speeds. The better highway mileage comes from the smaller engine and not the hybrid system. In other words, it would actually be better if the extraneous weight of the electric motors and especially the batteries could be dispensed with once a hybrid car is up to speed.
then it would really be efficient. But hybrids cars are actually better city cars than highway cruisers.
Boats, at least paddle-wheelers, are not concerned with accelleration or reclamation of energy upon stopping, and so any electric/diesel (or gas) boat hybrid is going to use electric motors to advantage as river current generators to charge batteries. Lots of batteries in fact, since there should be enough energy storage capacity to run the boat for a day at least.
Outside of river travel, I see no advantage whatsoever in a hybrid boat.
restricted to rivers, I see an enormous advantage since no engine is needed to charge the batteries, though there should certainly be an engine (genset)for backup and even (decouplably) shafted to the paddles.
Ground tackle becomes far more important if one is commonly anchored in a river stream. A mooring or a dock carefully chosen to take advantage of a fast current are other options.

Alan

[Rick Willoughby]

I would need to spend a bit of time to do some real performance checks but I think you would get acceptable performance from a couple of these new Mars PMDC on 72V:
http://www.kellycontroller.com/shop/?mod=product&cat_id=16&product_id=125
They are continuously rated at 9kW and will peak at 20kW. So get the gearing right and it should go OK.

I purchased a couple of PMAC Mars motors and 48V controllers from Kelly controllers and they posted them free to Australia. Cost for two motors and controllers was USD1540. I am very pleased with the motor and controller but would opt for the bigger one for the paddlewheeler shown. Not sure if you viewed my first test with the Mars motor:
http://www.youtube.com/watch?v=2ul6hDx1L50#GU5U2spHI_4
That is running from two tiny 12V batteries. The unit will crank out 9kW at full power using suitable 48V batteries.

Once you get above the 72V level you are getting into more serious electrical technology and you need some electrical nouse. There are some nicely engineered systems coming on the market for diesel electric hybrid.

A feature of the paddlewheeler is the large cabin top that could be used for solar collection. The panels would be expensive as fuel will be if you are permitted to use it for recreation. A lot depends on how far and fast you want to go at any time. You could also use a decent size wind turbine if the place gets wind.

Rick W.

[lazeyjack]

there seems to be no cheaper solution, than fossil fuel for us,
You can place a good argument for dc generating at anchor in fast streams, but there is always the huge cost of the battery bank and the regulating gear I think the future will take us round to small auxillary engines and sail, and thats where it all started really when power came into private boating

[ted655]

I was thinking of the simplicity of the mechanical & control systems Doing away with all the shafting, connecting & clutching. The ability to not need permanent engine room workers to relay orders from the pilot house. Making for a more responsive boat.
Going upstream in strong currents would require straight diesel-electric power? Perhaps electric driven prop also?
BUT, my main interest was a calm water, morning excursion-evening dinner boat for small parties.
I've been on several such boats where the paddle set solely on bearings, appearing to turn. Diesel screws actually supplied the drive. Something is "lost" in that experience!

[Rick Willoughby]

What size boat are you thinking about - length, beam and displacement?

If the paddlewheels are sized for the job they are efficient for operation in calm water. A twin wheeler will also maneuver well.

If it is just for night time cruising then straight electric and batteries connected to shore power for charging would be a good solution. The motors and batteries would not be any heavier than diesels and associated gear.

Here are some ideas:
http://cruisingresources.com/Electric_Propulsion__p2

I liked the FEYS system but their site no longer works - maybe their system was not very good!

Rick W.

[ted655]

========"What size boat are you thinking about - length, beam and displacement?
"====
Nothing big. Big "event" paddles seem to be going bankrupt. I think it's the formula of operating, berthing costs/overhead, not overcoming the loss in traffic. That is why the size boat I posted caught my eye. Like Goldy locks bed, it seems just right.
I think day excursions would also be necessary, in addition to dinner cruises..
I realize this is a hybrid section more than a diesel-electric, but I'm convinced some form of this technology is what's to come.
How are the insurance & finance boys treating this type of propulsion?

[alan white]

I was thinking of the simplicity of the mechanical & control systems Doing away with all the shafting, connecting & clutching. The ability to not need permanent engine room workers to relay orders from the pilot house. Making for a more responsive boat.
Going upstream in strong currents would require straight diesel-electric power? Perhaps electric driven prop also?
BUT, my main interest was a calm water, morning excursion-evening dinner boat for small parties.
I've been on several such boats where the paddle set solely on bearings, appearing to turn. Diesel screws actually supplied the drive. Something is "lost" in that experience!

Yes, I agree that something is lost in such fakery.
Any electric drive is going to require gear reduction as much as any fueled engine. I believe the complication increases rather than decreases if you drive the wheels electrically. The power plant can be smaller, but I think you'll find that the overall cost will be a lot higher, factoring in batteries, controllers, and so forth.
Without river current to regenerate, shore power or an onboard genset are required. The propusion could then be silent because you could generate during off-hours.
A lot of sawmills are going belly up and big electric (three phase) motors would be going for a song. Batteries are expensive, but what isn't?
How about four husky Clydesdales running a vertical merry-go-round arrangement? A single truck axle with the input going straight up to the horse deck. Individual brakes to turn the boat. No more gearing than the differential itself. You'll make a killing!

A.

[ted655]

By simplified, I meant ridding the interior of all the myriad of mechanical contraptions it takes to get power from the engine, OVER to each wheel. I'm assuming the electric motors would mount closer to each wheel, with far less chains & belts. Reverse would not be the burden it is on a mechanical drive, etc..
controls should be simpler. Video cameras & sensors could take the place of a full time engine room attendant. I just suppose a cleaner, simpler plumbed boat. I'll catch hell here maybe, but I envision a straight diesel-electric boat, no batteries, for a boat this size. But, I have an open mind & there is probably a good argument for hybrid.
This boat is obviously heavy built. A new boat would be lighter, with smaller wheels perhaps. A boat capable of 20 guests for supper & maybe 30 people for a short cruise. A crew of 5. :confused:
I'm just feeling around, getting to know "stuff" These links are great help, thanks.

[Rick Willoughby]

The beauty of a true paddlewheeler is the tiny amount of power that is actually required if you only need to do a few knots. Large wheels will give high thrust for little power.

You are correct about the motors. Modern controllers are fantastic. You can get them for either AC or DC motors and the motor/controller combination give efficiencies 85 to 90%. The Mars motor I have ticks over with 4W and it has a rating of 7kW on 72V. It only weighs 11kg. It can be used for powering or regenerating in either direction. The controller drains 60mA when connected so really only needs a fuse for safety and mechanical connector for disconnecting.

So you just need to find a nice neat triple stage epicyclic reduction box on a torque arm to mount on each paddle wheel that is continuously rated around 10kW and say 4000rpm input speed. Would not even need a rudder.

Modern electronics really make things simple. If you are charging from solar panels you do not need to worry about matching voltages. The controller takes care of it. Most units these days have charge maximising strategies built in to automatically hunt out the best operating point for the solar panels.

Rick W.

[alan white]

Hi Rick,

Could enough wattage be gotten from a solar array mounted (to articulate?) atop a paddle-wheeler roof top?
It would be nice if this could be done. What is the yield in watts per area under ideal conditions? Let's assume the area available is 30 sq. meters.
Let's further assume the panels can articulate on one plane.
If there are two max 10 kw electric motors (total 27 hp), is that enough power to safely navigate in strong currents? Low speed efficiency (meaning low kw power) is fine in calm water, doing four knots for an evening dinner cruise, but what kind of power would be required to stand up to a 6 kt current? Maybe four times that?
I'm assuming a boat of about forty-five feet, maybe 12 ft beam.

Alan

[Rick Willoughby]

Alan
A well designed 45ft (say 14m) boat should move along at better than 6kts with that sort of power. I will see what Godzilla comes up with for a boat that will do 8kts and has WL beam of 3m. Lets say it weighs in at 4 tonne fully loaded.

You can usually find data for expected output from solar panels in a specific location. You could work on about 150W/Sq.m for about 6 hours a day in temperate areas. So your 30Sq.m could be good for 27kWh on a typical day. They would be expensive - something like USD30k. It is certainly best to have them track but I think this is a lot more complex. The value of doing this will depend on the latitude.

The Sanyo look OK but I have not been able to get any of these so have gone to another brand with similar efficiency:
http://store.solar-electric.com/sa190wahitso.html
http://us.sanyo.com/industrial/solar/downloads/Solar%20Cutsheet%20All%20HIP-xxxBA3%20Models%20-%20Effective%201%20April%202007.pdf

Once you start getting into the numbers you can see why I went for an easily driven slender hull. You need to look closely at the overall design and make the best of what you are using. The batteries provide expensive ballast as well as energy storage. This means you can reduce the WL beam but still have good stability. If the boat is operating in calm water the shape above the waterline is not going to matter much so you can widen above the waterline. Still need to be mindful of windage though.

Rick W.

[alan white]

Rick,

Is the displacement realistic at 4 tons? I don't know much about this kind of boat, but would have thought at least twice or three times that.

Alan

[Rick Willoughby]

Rick,

Is the displacement realistic at 4 tons? I don't know much about this kind of boat, but would have thought at least twice or three times that.

Alan

Alan
I was thinking of lightweight construction in aluminium or composite. It is a river boat. I am happy to use 8 tonne. As long as the target speed is below hull speed the wave drag should not kill it.

Rick W.

[Rick Willoughby]

Alan
I have attached what Godzilla produced for the 8t paddlewheeler with maximum length of 14m and minimum WL beam of 3m optimised for 8kts.

The attached power curve has an efficiency allowance of 80%. This is possible with good props and I think achievable with decent sized wheels.

Rick W.

[lazeyjack]

our new boat has 18sq/m roof, , it will be livaboard, in Europe, It will have 230, and 24 vdc, inverter and 800 approx amp hr batt
how would you see solar cells upon this craft?
In Germany I have seen whole vast supermarket roofes, feeding juice into the system, , as you walk in, there is a big tube, with the kw/h output changing as the sun peeps in and out

[Rick Willoughby]

You might find this map of interest. In a way it shows the new energy rich and you have to wonder why Australia does not have solar plants scattered around Alice Springs:
http://www.soda-is.com/img/carte_Ed_13_world.pdf

So one answer to your question is about as good as 9sq.m in Melbourne or 5sq.m in central Australia or mid Atlantic.

The map suggests Europe gets about 80W/sq.m average. This is over 24 hours per day and, I believe, on a horizontal surface. So in one day each sq.m would yield 80 x 24Wh = 1920Wh. Now a good solar cell will yield 18% of incident energy in electrical energy. So each sq.m will give you 345Wh in a day. With 18sq.m you can recover 6.2kWh on average each day. The charge/discharge efficiency will reduce that to about 5.5kWh. This can be improved if you do most of the running through the peak of the day and sit at night.

So this is what you have to work with. If you set up tracking you could expect quite a lot more but this is more complexity.

Your 800Ah batteries will give you heaps of storage at 24V. I would go up to 48V as this seems to be a more common voltage level and keeps wiring a bit smaller. Having big batteries give you lots of grunt in an emergency but they cost in having to carry them around.

To get reasonable performance I had to add the wind turbine. This has the advantage over sails that you can charge when at rest. If you have good tidal flow you could charge from the water when anchored. It gets down to operating efficiently. All these things are getting better and I think are practical now.

So if you are happy to mooch along then you might have something that is practical. Post a bit more detail on the boat.

Rick W.

[alan white]

Alan
I have attached what Godzilla produced for the 8t paddlewheeler with maximum length of 14m and minimum WL beam of 3m optimised for 8kts.

The attached power curve has an efficiency allowance of 80%. This is possible with good props and I think achievable with decent sized wheels.

Rick W.

Thanks. I'll check it out when I get back from work.

[ted655]

http://users.wirefire.com/gemort/the%20hull.htm
http://www.waterwheelfactory.com/
And, as usual, there is plenty right here on this forum
http://forums.boatdesign.net/showthread.php?t=5243
.
A project can always get upside-down in costs, but an attempt to lower overhead is also important in a commercial venture.
Almost certainly is an aluminum hull, with some type of nostalgic superstructure.. 45' is short, as is a 12' beam. A excursion boat could manage, but a dinner boat will need around 60' X 15' beam.Suitable galley, storage,heads for both sexes, dancing area & "romantic" walkways, etc.. To preserve the "look" of vintage riverboat, the hull can't have much deck overhang. Most of these diminutions would need to be waterline.
Tilting roof panels, port/strbd could be hydraulically operated to achieve optimum angle, in relation to boat position.
People, (and insurance companies), are afraid to go out in strong currents, I see no need to design for a Mississippi class boat, (8-16 knot currents). However, the ability to quickly return to port in case of health or weather emergency's should be designed for. To obtain certifications & insurance coverage, such power WILL be required.
.

[Rick Willoughby]

[url]......... To obtain certifications & insurance coverage, such power WILL be required.
.

Hull speed of 60ft boat is 10.4kts so operating up to this speed will be efficient. Is this adequate or do you want to go faster? Going above hull speed favours a cat type hull. Also increasing beam will add drag. Maybe a cat hull is a better option but then you have to work out how important is a classic look and can it be achieved with a cat.

Rick W.

[alan white]

Guessing a displacement of at least 50-60,000 lbs. Not to say you couldn't be lighter, but you've got a substantial vessel there.
I would suggest you size the motors to make hull speed plus 50% reserve but others may have better info. You can always have a big-prop 100 hp outboard on standby, and also use that for maneuvering in some instances by setting it up to steer a full 180 degrees.
At that size, steel is probably the cheapest material to build with.
The roof collectors (in LA) will be pretty flat during the summer season so there's the question of what you anticipate your active season to be.
I see no reason to size to Missisippi standards (16 kts? wow!) but the additional outboard would probably make the difference when conditions were adverse.
Keeping your cruise speed down to six knots will use a fraction of the power needed to do 10 knots. Once you have your displacement and general hukk shape, your waterline beam and length and depth will determine your "sweet spot", the speed that uses the least power to achieve. Every hull has a best speed. Higher speeds favor a longer waterline and lower speeds favor a wider beam in general. This has to do with wetted surface area to displacement ratios, where extremely low speeds require the least power as the hull shape approaches a spherical shape (wider and deeper). Higher speeds (short of planing) like long lean hulls with less frontal area (narrow and shoal).

Alan

[Rick Willoughby]

Here is a good site for solar radiation in the USA:
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/

It looks like that April will give say 5kWh/Sq.m/day in the south for a horizontal panel. Allowing 18% conversion efficiency results in 900W/sq.m/day.

If the boat is used primarily for dinner cruises then it could be moored in a particular way to maximise advantage of tilted panels.

Rick W.

[ted655]

:) People just want to move & look. 5knts will do that. More speed or power might be a requirement by others. I think the shallow scow shape of the tradistional riverboat must be part of the "package" Cats are for California. :)
The outboard (s) is a new thought. I was thinking of 2 more electric motors & under hull shafts/props, discreetly housed.
.
Are 2 or more motors ever belted to 1 gearbox, to add HP?
.
Looking at the solar pattern on that world map, makes me ask if overcast skies are figured in to the ratings? We have many cloudy, rainy days here in Louisiana. Those #s look high for this state, but I really don't know.

[Rick Willoughby]

This is the way to get beam overall with a narrow hull:
http://www.slv.vic.gov.au/pictoria/b/3/5/doc/b35771.shtml

Also it has really only been in modern times with cheap fuel that we have not needed to be concerned about overall efficiency. In the early days of ship design they had to work with much less power to achieve their ends. Here is a good story.
http://www.pabook.libraries.psu.edu/palitmap/bios/Fulton__Robert.html

I will see what Godzilla produces for a 60ft boat displacing 15t optimised for 10kts.

Rick W.

[Rick Willoughby]

:) ....
Looking at the solar pattern on that world map, makes me ask if overcast skies are figured in to the ratings? We have many cloudy, rainy days here in Louisiana. Those #s look high for this state, but I really don't know.

From looking at other maps I believe the world map does not figure overcast conditions. I think the one I posted on the US does. I have one for Australia that certainly allows for clouds and it is lower than the world map.

Rick W.

[alan white]

:) People just want to move & look. 5knts will do that. More speed or power might be a requirement by others. I think the shallow scow shape of the tradistional riverboat must be part of the "package" Cats are for California. :)
The outboard (s) is a new thought. I was thinking of 2 more electric motors & under hull shafts/props, discreetly housed.
.
Are 2 or more motors ever belted to 1 gearbox, to add HP?
.
Looking at the solar pattern on that world map, makes me ask if overcast skies are figured in to the ratings? We have many cloudy, rainy days here in Louisiana. Those #s look high for this state, but I really don't know.

IT shouldn't make any difference whether there's a single large motor or two motors belted or geared to a single output. The additional motor adds its power to the first.
Any transfer through parallel shafts (gears, chain, or belts) means a certain percentage of power is lost in friction. gears and chains are generally most efficient, and gears last longest by far (and are not subject to catastrophic failure like chains or belts).
There should be no need to connect motors together though. Better to use a higher rated motor to begin with. Otherwise, there's too much complication and parts to maintain.
Having two motors to drive seperate paddles is ideal. Any other powerplant should either be a genset or an auxilliary diesel for an alternate propulsion source, or both. The auxilliary engine could be a shafted prop or an outboard. Running the paddles from it could be done, but would make for unneeded complication.
If the shafted prop setup is connected parallel to the generator, the generator could serve as an electric motor as well. A single prop should be fine.
Then you would have three electric motors, all of which can generate, and one diesel engine, which either provides extra thrust, or makes kilowatts when the sun isn't shining.

[Rick Willoughby]

I looked at the 60 footer displacing 15t. I have attached a rough rendering and a performance calculator for a paddle wheeler shown. The dimensions of the wheel in the calculator are the same as in the image but you can play with it to see how efficiency changes. The efficiency with wheels as shown is a bit over 60%.

You would do better with props but you get slightly better pulling power with the wheels despite the lower efficiency at speed. The wide set wheels also give good steering in tight spots at low speed.

If you go for a couple of these compact pancake motors:
http://www.perm-motor.de/pm_pdf/pmg_132_e.pdf
you could expect around 8kts with the big wheels shown using rated motor torque.

The nominated gearing provides the following performance:
Burst speed at twice rated torque, motors at 3300rpm, is 10.1kts.
Rated speed at rated torque, motors at 2500rpm, is 8kts.
Economic cruise at 1600rpm gives 5kts with combined motor output of 2.8kW.

All the performance figures are for clean hull in calm conditions.

Rick W.

[ted655]

:eek: Wow! Thanks so much, You've done things I could never do, & everyone has enlightened me! Thank you all.
The reason I started this inquiry, was a TV commercial. They show a gallon of "fuel" & say how a efficient automobile MAY get 40 miles from that amount. Then, they show a diesel-electric locomotive/train, and claim that same gallon will go 240 miles.
I realize there is velocity & mass, etc., involved in their claim, & they probably get no where near that when switching & making the train, but still...., diesel-electric seems the future. You fellows take it even further with the hybrid approach. AHH, if the storage technology would ever catch up, and/or, come down in price.
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While the hull you created is more modern than what I was thinking, it is very close & gives me a ton of information.
I would only have 4 degrees deadrise, a wider, rounder bow & straighter sides. I also had thougt a 5M wheel diameter, might give more power with less motor. Also allow for a narrower width, giving more deck/cabin width.. I did want the wheels set into the sides of the boat. I had no clue as to the location of the wheels. I "guessed" they needed to be past amidship. I had no idea how far.
It's taking a bit for this Yank to work in metric, but it good exercise for my brain. Thanks again. :)

[Rick Willoughby]

The hull shown is actually optimised for 10kts and a stability criteria with KMT at 2.5m above the keel. It just happened that the waterline beam ends up at 3.5m. It does not matter much what is done above the waterline as long as it can be built practically. If you load the hull with a tonne or so of lead batteries along the keel it will make it very stable. This would give ample cruising range on batteries alone.

Going to bigger diameter wheels will improve their efficiency providing width is not reduced. The gearing needs to be 99:1 and power for 5kts drops to 2.4kW.

You can play with the yellow cells in the Excel spreadsheet to see how changing the wheel size affects performance of the boat. The hull data is accurate for calm conditions and unfouled. I have never personally tested my paddlewheel calculator but It aligns with data provided by others. You need big wheels to get the efficiency up.

The Perm 132 motor spins to 3300rpm. Each motor has rated torque of 20Nm and they can be pushed to twice that in bursts. The duration will depend on motor cooling. You would need thermal protection if you planned to run for long periods at full power. Cell b24 in the spreadsheet gives the combined motor torque. This can be 40Nm at rated load and 80Nm for peak conditions.

Rick W.