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carstendenmark · 18-12-2020, 23:00

Hi, electric boat owners !

I am soon going to make a conversion from diesel to electric propulsion.

Did any of you, with experience of this type of engine, have had engine stops or stalls when using the motor ?
If so, what was the failure, and the actions that you took ?

It would be nice to know what to look for, to prevent this to happen :-)

Thank you for your valuable replies, guys !

**tkeithlu** · 19-12-2020, 04:35

There is extensive discussion of electric propulsion on the forum of late. It centers around not having enough energy to do the job without installing an even larger diesel than necessary for direct diesel drive, given the loss of energy in transfer through batteries and the need for a reliable source of propulsion at a critical time. Apparently, it's difficult for even the pros to arrange an efficient system.

I don't know where you are in designing your system. If you've got a plan already, how about posting it for discussion? There are several members who would like to see a solution.

In answer to you direct question, electric motors are pretty stall-proof, unless badly sized, and have the distinct advantage of whopping torque when reversed by switching the direction of the field. Minesweepers use diesel-electric drive for this reason.

carstendenmark · 19-12-2020, 05:55

# tkeithlu
Thanks for your reply.

I have a plan of course.
Likely a type like the watercooled Thunderstruck 18KW, derated to 12KW by 48V, with heavy toothbelt reduction to drive a much bigger prop than present, to get high torque. I'm also considering other (feathering) prop designs.

But before finalizing the design of the engine system itself, I would like to know how to avoid other's mistakes, by letting me know what went wrong by their system during actual sailing, using the motor.
Electronic failures, overheating, misalignments of shafts and gears, etc. resulting in stalls or engine stops.

Some of the mechanical setups I have seen described seems not sturdy enough (and some even lacked a proper thrust bearing), so the motor and system may have faced problems !

The electronics and power banks replaces the chances of "faults" in a diesel fuel system, just in another way. (And it does not smell as much.)

That is why any experiences of "gone wrong" is of help to me, designing a "near perfect" system for my 3,6 tonnes 29'er sailboat.

Almost ALL conversions has been done, and will be done, by individual DIY's like me. No streamlined pro's to consult yet, unfortunately :-(

If there was a way to just pay some guys for installing the perfect system, then I'll go for it.
Can't be any more expensive, than to install a new diesel...

We are coming into an area of new battery systems (well designed) at low prices, and the reliability of electric motors, that can't be beaten for the average coastal cruiser.

So my hope with this thread opening is to collect as many bad experiences as possible, and convert them into something reliable and useful, for me and others to enjoy.

I am not religious at all (in any way), and I'm not saying that electric is THE way for everyone, definitely not.
But when it IS the best solution, then it must be something that we can RELY on, when we're hitting the throttle to power up the silent and smell free electric motor.

carstendenmark · 19-12-2020, 06:28

As OP :

As a retired supervisor and mechanical expert of super large diesel engines for Wärtsilä and MAN B&W, working on location at the manufacturer's plants in South Korea and China for 10 years, I may have a slight advantage of designing reliable mechanical systems.

In that respect, I am a novice in electric systems design, but willing to learn !

I want to put my experiences into my own little sailboat, and if that can help others, I have contributed to something too.

Therefore I need some help from you electric engine boat owners.

For the ongoing theme of global warming - the efforts we put into the diesel engine designs is not to reduce CO2 (we can't do much about that, burning fossile fuels), but to reduce pollution, especially NOx.

**skipmac** · 19-12-2020, 08:37

Have no extensive experience with electric motors on large boats but am an EE and have some experience with electric motors in other applications including industrial.

Generally electric motors are quite reliable short and long term as long as you keep them dry. The most likely failures will come from controllers, switches and wiring.

Failures on the motor itself are most likely due to overheating or even running at the max rated temp for long periods.

Skipper Lee · 19-12-2020, 09:21

I have done the Thunderstruck conversion, I used the 5 Kw kit with 2-1 reduction spinning a 13rh11 prop for my 27 ft sloop at 4900 lbs. I was told by Thunderstruck that it would be as powerful as the Yanmar SB8 that it came with. I have yet to finish the conversion as it is winter here in central Canada but will be running in spring.
I do know a friend with the same boat as mine in Nevada who used the 5 kw kit as well. He is up and running he is well satisfied with the conversion but chose poorly imho regarding the batteries (Walmart) and he only gets about 1.5 hours run time on lake Mead.
I suppose it is enough for a lake boat left at a dock every night with power or just an overnight now and then.
I just purchased 6X12 Volt 110ah Firefly group 31 batteries.(2 house and 4 Drive) and that's likely the best you can do. Of course you can go Lithium as well if you choose but during other endeavors I have had them catch fire and burn the counter I was charging them on so I am slightly scared of them after replacing the countertop. I also purchased a 2000 w suitcase generator for use if needed while out on the water or charging at anchor. I saw your boat on sailboat data and like mine there's not much room for Solar panels though you might fit a few to assist or perhaps you'll add a tower for more or add a wind generator. not to many people actually get enough Regen on slower electric boats, or any boat, even big bucks professionally set up systems (like Jimmy Cornell recently found out). I suppose it all about how and what your sailing goals are.
I really enjoy the quiet life and will be listening to the meanderings of my mind while I learn how to get the best of my E-Powered backup drive system on my SAILBOAT.
I also had a 26 ft sailboat for 3-4 years without any aux power so yes you can do it with electric power.
Good luck and merry Christmas.

fred4936 · 19-12-2020, 10:03

We sold our Tartan 27-2 that was ( and still is, the new owner loves it too) electric, only had three issues in nine years. I have already had three issues in two season with the diesel in our new boat. Anyway, one was the throttle, which failed, and the other two was the encoder on back of the motor. Replacing the encoder involves taking the motor off and apart. To be fair, I bought the electric new in 2011, and the diesel came with our current boat, built in 1989.

fred4936 · 19-12-2020, 10:07

Skipper Lee, beautiful install!

Octopus · 19-12-2020, 13:11

Quote:

Originally Posted by carstendenmark

Hi, electric boat owners !

I am soon going to make a conversion from diesel to electric propulsion.

Did any of you, with experience of this type of engine, have had engine stops or stalls when using the motor ?
If so, what was the failure, and the actions that you took ?

It would be nice to know what to look for, to prevent this to happen :-)

Thank you for your valuable replies, guys !

I've owned a diesel electric Lagoon 420 Hybrid catamaran for 13 years.

I'm not sure what you mean when you ask about stop stalls. The electric motors are bulletproof and maintenance free. It's the charge control system and lead acid batteries that are the weak links in my system.

The only time we've had what might be described as a stop stall situation was one time we got ropes from a fishing pot round one of the props, which stopped the motor. Once I realised what had happened, I was surprised at how easy it was to get the ropes off the prop. It basically pulled off as the prop rotated. Not sure if that was because the motor controller sensed the increased load early and cut the power. Or I may have just been lucky.

On the whole the system has been brilliant and relatively trouble free. The few problems we've had with the system are as follows:

1. The battery chargers all failed and I'm in the process of replacing them. I'm taking the opportunity to replace the lead acid batteries with LiFePO4 batteries and install a new charge control system.

2. The Onan generator cut out once for no apparent reason and we failed to notice straight away, because the generator is so quiet, by which time we were motoring up a reef strewn channel to Le Marin, Martinique, and very low on battery power. Fortunately we just had enough battery power to motor to a nearby anchorage. It transpired that the oil pressure sensor had failed on the generator, causing it to incorrectly report low oil pressure and shut it down.

3. During a service, my nephew fitted a seal upside down in the generator's fuel filter, so we had no power for ten hours in the middle of the Bay of Biscay, until I worked out what was wrong.

4. On one occasion I relocated a connector block for one of the motor sensors and inadvertently reconnected it the wrong way round, which foxed me for quite a while, as it was a few weeks later we tried to use the motors.

5. A relay triggered by the on/off key failed in a busy shipping lane off Gibraltar, turning off the motors. Fortunately I tracked it down pretty quickly and jammed it in the on position.

The main issue with the system is the complexity of the control systems, which means that when something goes wrong you are pretty much on your own to diagnose and fix it.

Other than that, I love the system. It's super quiet, very economical, very easy and cheap to service and maintain, provides an abundance of electrical power for other uses and provides incredible manoeuvrability, due to the big props and instant torque.

Skipper Lee · 19-12-2020, 15:48

Thanks Fred,
Cleaned scrubbed and painted is a good starting place.
I do however wonder if anyone else thinks I could/should remove the Chain coupler entirely as I now want to push the motor back as far as is possible to get enough room in the area left by the removal of the Yanmar for the 48 volt pack.
The batteries are within 100 lbs of the Yanmar's weight so she should hold her lines better than if I jam the batts here and there. I think I want them right where the diesel was and if I push the motor aft I could just fab up a new mount and set up a battery station in the void.
I just think it would be one less area of noise eliminated. I may go so far, if required to get a longer shaft made to whatever is the most aft that can be achieved for motor placement.
I would just need to remove the prop shaft from the lower coupler on the reduction plate to slide the shaft back for service/removal as required. I think i will also get a dripless shaft seal in place even though I just repacked the stuffing box.
Does anyone mechanical know why this idea would suck?
Anyone think it will reduce friction, have less gear to line up correctly and just be an improvement?
I am really considering trying it, it wouldn't be my first mistake ever or anything but I don't see a down side> Anyone?
Food for thought while you plan your E-Project, Good luck.
Regards.

PineyWoodsPete · 19-12-2020, 16:23

The only problem we've had in our '14 33' Greenline M/C hybrid (165hp diesel inline with water-cooled 7kW/5kW motor/gen) has been with the single-lever control w/ integral potentiometer, relating to the fast-idle button not being entirely released. Cured with a couple of WD40 shots around it and working the button a bit.

It's a clutched either/or setup, driving the same 17x14 5-blade prop through 2:1 reduction. Up to 1350 RPM (vs 4000 top for diesel) at full 150A-50V (7.5kW) for a minute or two, then settling down to 125A (6.25kW). Top speed ~5kt, with range said to be about 10nm with full 11.6kWh LiPo pack, or ~15 @ 4kt. The OP's 3500kg sailboat vs our less efficient 5500kg would prob. add another 1-1.5kt at same settings, so his 20kW motor should get him to hull speed with power to spare.

Murraybrowne · 19-12-2020, 18:20

Quote:

Originally Posted by carstendenmark

Hi, electric boat owners !

I am soon going to make a conversion from diesel to electric propulsion.

Did any of you, with experience of this type of engine, have had engine stops or stalls when using the motor ?
If so, what was the failure, and the actions that you took ?

It would be nice to know what to look for, to prevent this to happen :-)

Thank you for your valuable replies, guys !

Hi, My son and I recently converted a 1973 Dufour 41 to electric. We used the Thunderstruck 18KW and 8 x L16 lead acid batteries to get 48V and 410 amp hours. The Thunderstruck motor is good but very DIY. Some other kits come more ready made. We constructed a frame/ engine mounts out of stainless square bar with jacking mounts and A-Frame supports of stainless flat bar.
The electrical system and controller weren't bad to hook up the the cooling system from Thunderstruck was pretty janky and needed a lot of parts and adaptors.
Does it work? Yes, if you are patient. Our range is limited, about 30 nm cruising at 3-4 kts for a 20,000lb boat. We have a 3-1 gear ratio with belted teeth. The electric motor is beautiful, smooth and quiet. It just has very limited range. This is fine for what we do and when we sail or have sun, can go farther.
We also custom made a carbon fibre bimini with 2 massive 400 watt 48v solar panels. We have a Victron Quattro 48 for charging in port and as an inverter. We have a DC-DC charger to charge or 12V house system from the 48V motor system.

Not sure how it would work offshore or motoring against heavy sustained winds or currents. I think you would need a generator. Other than that's it's fine and very environmental. The lack of diesel fumes and noise are also very enjoyable.

Please let me know if you have any questions. My son is the wizard on this but between us we could probably answer most questions.

Murraybrowne · 19-12-2020, 18:23

Hi, I just posted a detailed reply. I should have mentioned that the chain coupler is not very rugged. We had a machine shop manufacture a custom coupling.