# Large slow boat conversion.



## einherjar (Nov 8, 2010)

I've got a new project I would like to get some input on. 

It's a large old houseboat. 44' steel, 16,000lbs. Currently powered by twin Chrysler 225 V8's.

The motors are such a hassle all of the time that it hardly gets used because there is something wrong with it. The boat is used just for slow cruising (3-5kts) up and down the river. Usually not more than 8 miles normally. So the hp / high speed that the current engines provide are not that important.

To me it seems like the high torque properties of electric motors would be a great feature for a boat like this. Sure it weighs a lot, but size the prop accordingly and you can push a lot at low RPM. 
Also battery capacity might not have to be that large due to the normally short distance and low speed that it travels. 

Initially I was thinking a pair of heavy duty DC motors no more than 36-72v. There is a generator in the boat too, so there will still be some gas involved. I've heard it's a bad idea to do DC with the possibility of gas vapor near by, so maybe AC is better. Also the possibility of a single motor driving both props, though then most likely I'd lose the option of pivoting (one F one R). As it is a large displacement boat heavy batteries isn't the much of an issue. Probably make a couple of packs so one can be charging via solar / reserve while the other is used. 

Any input on size of the motors and type and project in general is appreciated.


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## samborambo (Aug 27, 2008)

What did you decide to do with this in the end?

For your application, a pair of industrial cast iron AC induction motors running off VSDs would be fine. They're designed for 100% duty cycle and are hard to break. There are some online calculators to work out power vs water speed based on your hull LWL.

You'll need a higher voltage battery pack for a standard AC induction motor (at least 1.4 times the AC motor voltage). The other option is to rewind the motor for low voltage. Motor rewinders will do this if you provide them the spec you want.

If you go with standard industrial motors, you can use standard VSDs but connect the battery pack to the DC bus inside the VSD. You could even get away with one VSD and a reversing contactor to run both motors with V/Hz mode (can't do vector/FOC drive in parallel).

Sam.


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## Duncan (Dec 8, 2008)

Hi
Ref your boat - at 3 - 5 knots - you are getting into horse drawn territory! - a single horse can pull a 40 ton barge at walking pace 

So you really don't need much power

The secret of efficiency with a water screw is large amounts of water pushed back slowly - so a big low rpm prop is best 

I don't know about sparks and corrosion but a pair of forklift motors running on 48v would give more than enough power


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## Emyr (Oct 27, 2016)

Duncan said:


> The secret of efficiency with a water screw is large amounts of water pushed back slowly - so a big low rpm prop is best


Big low rpm Archimedes screw, yeah?


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## Duncan (Dec 8, 2008)

A large three blade prop is a LOT more efficient than an Archimedes screw


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## nucleus (May 18, 2012)

I think you need the power reserve in case the wind comes up.

Also, the safest route prop-wise is to stick to what is already there.

I think a pair of HPEVS AC-9's could be the ticket.


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## Duncan (Dec 8, 2008)

nucleus;1018539
Also said:


> And the safest way to do any conversion is not to do it


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## brian_ (Feb 7, 2017)

nucleus said:


> Also, the safest route prop-wise is to stick to what is already there.


That would make sense if the intention was to operate at similar speed as the original configuration. It seems that the intention is for slower operation.


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## boekel (Nov 10, 2010)

nucleus said:


> I think you need the power reserve in case the wind comes up.
> 
> Also, the safest route prop-wise is to stick to what is already there.
> 
> I think a pair of HPEVS AC-9's could be the ticket.


Yes for power reserve!

old prop can be a start when you don't know your motor characteristics, then adjust until right.

old prop usually means you need a big rpm reduction (you'll need that anyway in most situations).


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## Peterboat#1 (Mar 1, 2018)

I am nearly their with my conversion, my old forklift motor is mated to the propshaft batteries and controller mounted and cabled up. This week its other wiring and and a test run hopefully.
My boat is 57 x 12 and weighs over thirty tons and I am happy cruising the inland waterways at 3 -4 mph. Charging is taken care of by 3.6 kw of solar on the roof.
In the end I suspect I will be fine tuning the propeller, but you never know it might be right


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> I am nearly their with my conversion, my old forklift motor is mated to the propshaft batteries and controller mounted and cabled up. This week its other wiring and and a test run hopefully.
> My boat is 57 x 12 and weighs over thirty tons and I am happy cruising the inland waterways at 3 -4 mph. Charging is taken care of by 3.6 kw of solar on the roof.
> In the end I suspect I will be fine tuning the propeller, but you never know it might be right


What kind of reduction gear do you use?


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> What kind of reduction gear do you use?


 Its direct the original diesel worked through a 2 to 1 gearbox, the top revs were 3100, the electric motor I have chosen has a 1680 rpm at 48 volts.
I have used a 60 volt system but dont expect to get anymore rpm,and to be honest dont want to do the 7 - 8 mph this achieves anyway.


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> Its direct the original diesel worked through a 2 to 1 gearbox, the top revs were 3100, the electric motor I have chosen has a 1680 rpm at 48 volts.
> I have used a 60 volt system but dont expect to get anymore rpm,and to be honest dont want to do the 7 - 8 mph this achieves anyway.


Be carefull when testing, you -do- need a reduction gear, don't burn out your motor!


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> Be carefull when testing, you -do- need a reduction gear, don't burn out your motor!


Oh no! It is a series motor which I understood to have lots of torque at low rpm so thought it would be ok. I will monitor the temp of it whilst on test to see how it performs


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> Oh no! It is a series motor which I understood to have lots of torque at low rpm so thought it would be ok. I will monitor the temp of it whilst on test to see how it performs


yes that's good for a car, on a boat it doesnt matter you want continuous power in a boat, and if you turn too slow you don't have enough power.

Higher voltage = higher RPM

what controller do you use?


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> yes that's good for a car, on a boat it doesnt matter you want continuous power in a boat, and if you turn too slow you don't have enough power.
> 
> Higher voltage = higher RPM
> 
> what controller do you use?


Curtis PMC 1205M-6B403 400A DC Series Motor Speed controllor 

I suspect I am going to find out whether things are ok this week. I have various gadgets to let me know what amps its drawing etc so I will post the results. I was rather hoping that because I had matched the rpm of the moto,r to rpm of the gearbox all would be ok


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> I was rather hoping that because I had matched the rpm of the moto,r to rpm of the gearbox all would be ok


that is correct if the continuous power of the motor is the same as the power of the engine that came out.


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> that is correct if the continuous power of the motor is the same as the power of the engine that came out.


 I can always reduce the pitch on the prop, if the motor cant hit the revs that it did with the diesel engine, this week I hope to be trying it and as I say will report back.
For test purposes I will put my timing light on it and see what it says for RPM


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## boekel (Nov 10, 2010)

good plan, I usually also test with original prop first.

most of the times the pitch has to be halved, but that's probably a coincidence...

try not to use more than 250 motor amps at first (depending on the motor, what current / power is it rated at? diameter?)


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> good plan, I usually also test with original prop first.
> 
> most of the times the pitch has to be halved, but that's probably a coincidence...
> 
> try not to use more than 250 motor amps at first (depending on the motor, what current / power is it rated at? diameter?)


12 inch in diameter and 18 long I will look at the plate tomorrow, its not a problem to remove and repitch the prop so its a plan if it doesnt perform. I will watch the amps carefully which is why I am doing everything right first time


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## dain254 (Oct 8, 2015)

I would speculate that the motor controller would overheat and shut itself down long before the forklift motor would be hot at those amperages. I'm interested to hear how your first test went whenever it happens!


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## boekel (Nov 10, 2010)

dain254 said:


> I would speculate that the motor controller would overheat and shut itself down long before the forklift motor would be hot at those amperages. I'm interested to hear how your first test went whenever it happens!


the motor needs RPM to cool itself (or external fan).

problem is at low RPM you need lot's of current to make power. high current = high losses = heat.

but 12 inch motor...that's a beast!!


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## Peterboat#1 (Mar 1, 2018)

Its what was available, and the RPM was right, plus it was nearly new, its a drive motor with fan, and the job of putting a flange on it was easy, I am hoping that the warm/hot air will be ducted to the batteries to keep them warm, LifePo4s which give their best at 20 degrees or so. I was hoping that cruising would have an RPM of 700 or so and not to large a current draw, I will soon know fingers crossed for success


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> the motor needs RPM to cool itself (or external fan).
> 
> problem is at low RPM you need lot's of current to make power. high current = high losses = heat.
> 
> but 12 inch motor...that's a beast!!


Well today the motor was spinning in anger and it can certainly strain the ropes, tomorrow I will have the meters in place so will know what amps its drawing, as for a beast you did say go for a big one, so I did..........


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## Peterboat#1 (Mar 1, 2018)

So Yesterday I had a trial run, it performs well draws 52 amps 3.3KW at approx 3mph, the temp of the motor was 72 degrees C at the end of an hour run, controller was 32 degrees.
It can draw over 300 amps but the breaker triggers at that, I suspect I will have to replace that breaker for a 400 amp one which is the maximum the controller can supply.
The boat performed well and performed as I expected it would, however I have bought a 24 volt blower motor to cool the motor down, I also have a slight out of alignment issue which I will sort next week.
So questions
1/ should I fit the 400 amp breaker or leave it at 300 amps?
2/ should I test it without the breaker to see what the motor really does draw at speed?

3/ Is 72 degrees to hot after an hour or is it normal? will running cooler help performance and life of the motor


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> So Yesterday I had a trial run, it performs well draws 52 amps 3.3KW at approx 3mph, the temp of the motor was 72 degrees C at the end of an hour run, controller was 32 degrees.


are you measuring motor amps or battery amps?
did you measure RPM?
dit you measure motor voltage (should be pretty linear to RPM)

it sounds like it's working well! 72 degrees C was measured on the outside or the rotor / stator windings? I bet you could smell the motor 



> 1/ should I fit the 400 amp breaker or leave it at 300 amps?
> 2/ should I test it without the breaker to see what the motor really does draw at speed?
> 
> 3/ Is 72 degrees to hot after an hour or is it normal? will running cooler help performance and life of the motor


cooler is better, try the fan. this also depends on how the motor is mounted (free flow of air or restricted)

I like to be able to draw full power for a short period, maneuvering (stopping!) needs power. you could make some 'spring return' on the throttle lever so it doesn't stick to full power.

Check the controller specs on continuous power rating.


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## Peterboat#1 (Mar 1, 2018)

I was measuring Motor amps cant, as yet measure RPM but will do as soon as I can work out how to do it reliably.
The fan will be here towards the end of the month, the motor has lots of air and room to breath in but as you say cooler the better so fan will be fitted.
I will do a trial to see how many amps the motor draws flat out, I want a cut out in the wiring, as if some rope gets caught in the prop it will cut out as the amps rise.


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> are you measuring motor amps or battery amps?
> did you measure RPM?
> dit you measure motor voltage (should be pretty linear to RPM)
> 
> ...



So I have ordered a tacho kit which is easy to fit, wont be here until the beginning of next month. At full throttle the motor is running at 370amps! I will be I suspect be repitching the prop to enable it to spin at aprox 2000 rpm. In the meantime I am fitting the steering wheel and hydraulics to convert it from a tiller. I will let you know how things go when the tacho kit arrives and can tell you what its current motor RPM is


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## boekel (Nov 10, 2010)

Cool! sounds good 

Here's some of my projects:

https://www.youtube.com/watch?v=v_nC-ebZdtU

https://www.youtube.com/watch?v=BzJbJ7NBBbo

https://www.youtube.com/watch?v=1dCABzvCnyE

https://www.youtube.com/watch?v=pO0yj2N8wuw

fun with the water scouts:
https://www.youtube.com/watch?v=q4rCF78aybg


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> Cool! sounds good
> 
> Here's some of my projects:
> 
> ...


Thanks for those, great videos, did you ever get out from under that bridge? I had, like you thought of doubling up on motors, it seems from that video they work very well together. We will be taking a video shortly so I will post it for you


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## boekel (Nov 10, 2010)

Peterboat#1 said:


> Thanks for those, great videos, did you ever get out from under that bridge?


Haha that was my mooring for 7 years, letting go of the ropes was enough to get going


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> Haha that was my mooring for 7 years, letting go of the ropes was enough to get going


No good for me I need the sun on my solar to keep my life running


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## boekel (Nov 10, 2010)

Ah yes, but while doing steel-work on the boat, it was nice to be out of the rain...and with hot weather it was also a perfect work location. (only west / east winds could get chilly)


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> Ah yes, but while doing steel-work on the boat, it was nice to be out of the rain...and with hot weather it was also a perfect work location. (only west / east winds could get chilly)


Cant fault you, on a number of occasions whilst getting soaked, I have wished for an instant boat shed!
At the moment I have a problem with vibration on my drive flange to the propshaft, it is running very slightly off center and its driving me mad! Tomorrow I am going to visit propshaft technology in a hope that they can sort it out for me. I do have a centraflex coupling that removes some out of balance issues, but bearing are easily damaged so an expert is required in this case


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## Peterboat#1 (Mar 1, 2018)

boekel said:


> Ah yes, but while doing steel-work on the boat, it was nice to be out of the rain...and with hot weather it was also a perfect work location. (only west / east winds could get chilly)


 Right everything is back and assembled tacho connected, the motor spins at 933 RPM flat out, my prop is 19 x 10 if I remember right, the motor should spin at 1600 rpm so what do think for a repitch? 19 x 7? or maybe less even. Look forward to hearing your thoughts. 

As an afterthought the prop used to spin at 1500 rpm with the 50 hp diesel so it hasnt lost much in conversion


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## boekel (Nov 10, 2010)

That sounds about right, you can also play with different rpm / power on this website:

https://www.vicprop.com/displacement_size.php


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## Peterboat#1 (Mar 1, 2018)

So today I acquired a 16 x 14 prop, I have decided to give it a go and have been removing the prop through the weedhatch, so much fun as you probably know, I will post the result next week when I get the old prop off with the puller!!!


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## Peterboat#1 (Mar 1, 2018)

So in the end I cut down my original prop from 19 x 10 to 16 x 10 ish, this achieved a good upping of the RPM. I have been out for a run from Rotherham to Sheffield and the boat performed well, the batteries recharged from the solar quickly enough to make the boat fit for what I want which is 2 -3 hours cruising daily. I have to fit some change over switches so that all the solar can be for drive or domestic use, which is a job for next week.


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## MattsAwesomeStuff (Aug 10, 2017)

Keep us updates. Not much to comment on, but I'm sure lots of us enjoy reading and seeing progress.


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## Peterboat#1 (Mar 1, 2018)

So its pretty well sorted, I had a high pitched whine from the motor after about 7 minutes, I stripped the motor out and stripped it down, it has been reconditioned, but I changed the bearings and removed the fan as it was slipping on the armature. The cooling is taken care of by an electric blower, and the removal of the fan has increased the airflow through the motor.
The whine is still there but looking at some forums and talking to Cedric Lynch he seems to think its the pwm curtis controller that is causing this, its a frequency thing he says, only time will tell if it is a problem. In the end running this motor at a nominal 60 volts it using 24KW 381 amps flat out cruising is achieved at about 3KW so the conversion is a success for me


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## boekel (Nov 10, 2010)

Great to hear, enjoy!!


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## MattsAwesomeStuff (Aug 10, 2017)

Peterboat#1 said:


> The whine is still there but looking at some forums and talking to Cedric Lynch he seems to think its the pwm curtis controller that is causing this


Yep, they'll do that.

Better controllers use a higher frequency so that you can't hear it. Nicer ones occasionally send a different frequency to kill any resonance from building (like, 1/100 cycles will be slightly off, so that it never gets a chance to "sing" at a certain frequency, like pushing someone on a swing at the wrong timing, they never get a chance to build height).

I've been thinking of making a "Who's finished a project recently?" list, as there aren't actually that many to note, probably not even one a month. Yours would be on the list


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## electro wrks (Mar 5, 2012)

The whine might just be normal brush noise. You might try pulling the brushes and put a slight chamfer on the leading and trailing edges of the brushes. If the noise goes away-it's probably the brushes. The noise will probably come back as the brushes wear.


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## Peterboat#1 (Mar 1, 2018)

So more changes for the boat, today I collected 30 x 36 volt valance batteries I will connect 15 in parallel twice then connect them in series to give me 72 volts. I am still awaiting my new controller from Cedric in the hope of getting rid of the whine. 

I am hoping that the batteries and slightly increased voltage give me a longer no sun range and slightly better performance fingers crossed for both, I do wonder sometimes at our sanity when we start these projects but cruising along in near silence makes it all worth while


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