Electric inboard

[gdallas]

I’m toying with the idea of restoring a small weekender/ keelboat. Full keel, traditional construction, about 2 tons displacement light.
Originally built without any engine, I’m intrigued by the possibility of installing a shaft drive inboard electric motor with a propellor in an aperture in the rudder. This would be a true auxiliary and I would not expect to do a lot of miles under power.

Does anyone know of websites or other media where I can learn about various suppliers, equipment, systems? There are lots of manufacturers selling pod drives as integrated systems but I think I need to DIY a system: motor, mounting, batteries and management system, thrust bearing etc. And I’m hoping that there is a place for people like me to look. Or has someone done something similar?

Any ideas? Thank you

[Breakaway]

Both Elco and Torqeedo offer inboard electric motors. I am sure there are others.
Good luck!

Kevin

[Rich Jones]

There is a FaceBook group called Electric Boats and Electric Ships. You can get a lot of questions answered there.

[Nicholas Carey]

The Electric Boat Association - lots of electrified vintage boats.

https://electricboatassociation.org/

[rgthom]

Grin Technologies in Canada is an e-bike motor company but they have developed an electric inboard for sailboats. Maybe not easy to import to UK, but worth a look at how they did it. Several useful videos: https://ebikes.ca/product-info/grin-kits/marine.html

[leaotis]

variety here: https://plugboats.com/

[peb]

I’m toying with the idea of restoring a small weekender/ keelboat. Full keel, traditional construction, about 2 tons displacement light.
Originally built without any engine, I’m intrigued by the possibility of installing a shaft drive inboard electric motor with a propellor in an aperture in the rudder. This would be a true auxiliary and I would not expect to do a lot of miles under power.

Does anyone know of websites or other media where I can learn about various suppliers, equipment, systems? There are lots of manufacturers selling pod drives as integrated systems but I think I need to DIY a system: motor, mounting, batteries and management system, thrust bearing etc. And I’m hoping that there is a place for people like me to look. Or has someone done something similar?

Any ideas? Thank you

For my new build I chose Electric Yacht, electricyacht.com. Motor and everything is installed. Will be splashed this summer, so I can't give you any performance data. Fairly simple install, but I assume all of them are. Its a 48V 5Kwatt direct drive motor. My boat will weigh around 5000 lbs and is 24'7" on deck. It is an inboard.

There are many suppliers, and its been a couple of years since I made the decision so can't recall all of the details as to the selection. I wanted it to fit under the cockpit sole without needing a bridge deck, so the direct drive was a plus. I was advised on various manufacturer varying size of motors, anywhere form 2kw to 5kw. I will mainly use it for entering and leaving the marina and the occasional no wind, need to get home scenario, but I wanted to have enough power in the rare instance when I did need it. My old boat was a little heavier and I had a 2 cyl yanmar and in 20 years I can recall 2 or 3 times when I needed the power. Once when caught with a sudden storm on a lee shore and a scared crew, it was easiest to just power up the engine and get to safer water. Another time in a multi-fleet race where we lost all wind and after the race was called I towed a train of 10 J-22s and J-24s back to the marina a couple of miles (did not have to buy any beer that afternoon). So with the electric motor, I thought 7 hp was better than 2 or 3. But I normally sail, I don't motor, so there is no way I was going to deal with a diesel again when I literally spent more time maintaining it than I spent using it.

Of course there are downsides to the direct drive, it may not give me quite as much ultimate power or be quite as efficient. From the looks of it, everything is well manufactured. I haven't bought the batteries yet, so it has only been tested using my 48V battery charger as a DC-supply. The thing that seems off to me is that the controller seems to draw about .3 amps of power just when switched on. That is based on the display of the charger, and the tech support guy told me it must be that the charger display was not accurate. But with one of those gun type thermometers I could detect heat being dissipated from the controller, so who knows. I did rewire so that I have two battery cutoff switches: one for the motor and one for the 48V-12V DC converter so I do not need to leave the controller with power while sailing.

[stromborg]

It sounds like an interesting project. I dug in pretty deep trying to figure out how to electrify a classic keelboat design I plan on building in the next couple of years. motors and controls are really well sorted out but batteries are (IMO) the weak link, especially on a classic wood boat. Getting to decent cruising range still requires a lot of heavy, bulky batteries. Where do they go? How are to keep them dry? Does the boat have room for solar panels big enough to bother with?

Looking forward to seeing what you come up with.

[rgthom]

Out of pure curiosity I looked up the Electric Yacht and Grin equivalent power direct drive motors to see how they compare. A 5 kW QuietTorque lists for $5295 and weighs 40 lb: https://electricyacht.com/product/qu...lectric-motor/ while the Grin Marine 5 kW is showing at $675 and weighs 9 lb: https://ebikes.ca/catalog/product/vi...rine-motor-20/ The Grin is only in beta release to a few customers for now.

I have no connection other than using a Grin hub motor for my e-bike, but if you are willing to do more of the hook-up work and mounting the price difference is substantial.

[peb]

Out of pure curiosity I looked up the Electric Yacht and Grin equivalent power direct drive motors to see how they compare. A 5 kW QuietTorque lists for $5295 and weighs 40 lb: https://electricyacht.com/product/qu...lectric-motor/ while the Grin Marine 5 kW is showing at $675 and weighs 9 lb: https://ebikes.ca/catalog/product/vi...rine-motor-20/ The Grin is only in beta release to a few customers for now.

I have no connection other than using a Grin hub motor for my e-bike, but if you are willing to do more of the hook-up work and mounting the price difference is substantial.

I think I paid 4K for mine. It is a full kit, controller, throttle, motor, battery fuse, switch, control panel, solenoid, mounts. Of those, the controller and throttle would be the most significant cost. One can certainly build your own for substantially cheaper, but it would take a lot of work and design. The Grin unit you reference recommends a $1400 controller/inverter.

There is a video blog, Sailing Uma, where a couple cruise with a electric auxillary. They initially built their own and have since replaced it.

[Breakaway]

Peb, I would think it normal for the system to be drawing something when switched on. Indicator lights, the display, capacitors may be being charged, etc.
There are those much more knowledgeable here on electrics, but any component in the circuit takes some power and creates some resistance.

Kevin

[peb]

Peb, I would think it normal for the system to be drawing something when switched on. Indicator lights, the display, capacitors may be being charged, etc.
There are those much more knowledgeable here on electrics, but any component in the circuit takes some power and creates some resistance.

Kevin

Yea, but .3 amps at 48v is a 14watts, that's quite a bit.

[dbp1]

I think I paid 4K for mine. It is a full kit, controller, throttle, motor, battery fuse, switch, control panel, solenoid, mounts. Of those, the controller and throttle would be the most significant cost. One can certainly build your own for substantially cheaper, but it would take a lot of work and design. The Grin unit you reference recommends a $1400 controller/inverter.

There is a video blog, Sailing Uma, where a couple cruise with a electric auxillary. They initially built their own and have since replaced it.

Didn't they get sponsored by the replacement company? (so not totally clear that if money was a factor that they wouldn't have continued to work on their DIY one). That kind of stuff somewhat drives me nuts about the youtube channels: they pitch it as "you too can do this! Look!" except that most of the stuff they get is free (the worst is Jamestown... I swear they must have a robot watching for new youtube channels are just automatically start drop-shipping products). Some are better than others about disclosing it, of course

[peb]

They definitely got sponsored by the company. They were upfront about it and did not make out that it's was easily affordable. IIRC it was an Ocean Volt system, not a cheap option at all, but very well made.
I only watch (occasionally) their sailing videos and one other guy. I do admire how they do all the work themselves and really seem to do a good job. Their adventure into the artic was also quite impressive.

[peb]

The other thing to keep in mind about buying a raw motor and doing your own system is the housing and thrust bearing needs to be well designed and built. That would likely be as difficult as any electrical components needed to be purchased and put together.

[rgthom]

I think I paid 4K for mine. It is a full kit, controller, throttle, motor, battery fuse, switch, control panel, solenoid, mounts. Of those, the controller and throttle would be the most significant cost. One can certainly build your own for substantially cheaper, but it would take a lot of work and design. The Grin unit you reference recommends a $1400 controller/inverter.

There is a video blog, Sailing Uma, where a couple cruise with a electric auxillary. They initially built their own and have since replaced it.

Ah, that makes sense. The motor for my e-bike was the least expensive part, battery was by far the most.

[peb]

Ah, that makes sense. The motor for my e-bike was the least expensive part, battery was by far the most.

Brings up an interesting question about ebikes that I have not considered, surprisingly so since I own one. Are the motors on ebikes ac with an inverter, or just DC motors?

[rgthom]

Brings up an interesting question about ebikes that I have not considered, surprisingly so since I own one. Are the motors on ebikes ac with an inverter, or just DC motors?

My hub motor is 3 phase BLDC. I think most are the same since my controller can be programmed to run almost any motor.

[peb]

My hub motor is 3 phase BLDC. I think most are the same since my controller can be programmed to run almost any motor.

Thanks. I figured the motor was AC.

[Rumars]

An inboard is a lot easier to make then a pod drive. For an inboard you go to an ev store like cloudelectric or to your local forklift store and buy the components. Speed reduction, thrust bearing and mounting points are easiest done by using an old reverse gear. The driveline is conventional, same thing as any other boat, shaft or saildrive unit.

A pod drive is a lot more complicated. First problem is the motor form factor, you need it long and thin. This usually requires a higher rpm, so you need a gearbox in the same form factor. The thrust bearing mounting is the next problem and ties nicely with the housing problem, wich must transmit heat effectively, be solid enough and all penetrations be waterproof.

[J.Madison]

I recently got hands on with a vetus electric propulsion model, and I really, really liked it. So smooth and quiet, in a full install package with integrated thrust bearings. Not the cheapest but would be a very clean installation.

My only complaint was the electrics were not in a splash proof housing.

[Nicholas Scheuer]

I've looked into the Elco for my Albin-25. However, its range is not compatible with my cruising style unless the boat is equipped with more batteries than I can afford. The DuNORD's original motor is a Volvo-Penta M17C and it's getting tired.

[gdallas]

Thanks to all. This is a good forum. Useful food for thought.
I’m sort of maybe considering a restoration project on a small Alfred Mylne yacht, that has never had an engine. This would not be a boat for anything other than daysailiing, maybe an overnight. Not a cruising boat and no need to fret over range. But realistically with crowded harbours and rivers it is useful to be able to manoeuvre under power. I suppose I could use oars, a sweep haha. In theory!

Realistically I’d need power. One idea would be to have a tidy, removable outboard bracket and use an electric outboard. I’ve a little experience of these and they are impressive. But fitting & removing the bracket, assembling the outboard, then putting it all away…. Hassle. Delay. And it would be a bit clunky on a counter sterned boat even if done well.
I had a good Beta diesel in my last boat, no complaints. But access for maintenance was horrible, due to the hull shape. And it was smelly and oily and though smooth by diesel standards I still didn’t like the way it vibrated. And sounded.
I think I’d only be able to squeeze a single cylinder diesel in to the ‘new ‘ boat. Not very smooth at all!
I also thought about a Dolphin petrol engine. They are smaller and lighter and smoother than even a small diesel but it is a very old design, and though I’m not paranoid about carrying gasoline it is still going to be smelly and oily and will probably be unreliable. So, electric thoughts.

[gdallas]

They definitely got sponsored by the company. They were upfront about it and did not make out that it's was easily affordable. IIRC it was an Ocean Volt system, not a cheap option at all, but very well made.
I only watch (occasionally) their sailing videos and one other guy. I do admire how they do all the work themselves and really seem to do a good job. Their adventure into the artic was also quite impressive.

Ocean Volt does look very good doesn’t it. But pricey.

[peb]

Thanks to all. This is a good forum. Useful food for thought.
I’m sort of maybe considering a restoration project on a small Alfred Mylne yacht, that has never had an engine. This would not be a boat for anything other than daysailiing, maybe an overnight. Not a cruising boat and no need to fret over range. But realistically with crowded harbours and rivers it is useful to be able to manoeuvre under power. I suppose I could use oars, a sweep haha. In theory!

Realistically I’d need power. One idea would be to have a tidy, removable outboard bracket and use an electric outboard. I’ve a little experience of these and they are impressive. But fitting & removing the bracket, assembling the outboard, then putting it all away…. Hassle. Delay. And it would be a bit clunky on a counter sterned boat even if done well.
I had a good Beta diesel in my last boat, no complaints. But access for maintenance was horrible, due to the hull shape. And it was smelly and oily and though smooth by diesel standards I still didn’t like the way it vibrated. And sounded.
I think I’d only be able to squeeze a single cylinder diesel in to the ‘new ‘ boat. Not very smooth at all!
I also thought about a Dolphin petrol engine. They are smaller and lighter and smoother than even a small diesel but it is a very old design, and though I’m not paranoid about carrying gasoline it is still going to be smelly and oily and will probably be unreliable. So, electric thoughts.

I would think installing any inboard in a boat that never had one is quite a chore, since you would have to bore the shaft tube. Have you looked at any of the pod type electric engines? My build has a full keel and I did not think they would work well, same might be the case with you.

Keep in mind that range increases greatly at lower speeds. My boat is about 25 ft, and weighs in at 5000 lbs approx. It should reach hull speed in calm water at aroudn 3500 watts. I am trying to put in about 120 amp hours of 48V power (lithium), so will have 100 amp hours effective. That only gives me about 1.5 hours at hull speed. But from what I have been told and based on my own research, I think I should get perhaps 6 hours easily at 4 knots of speed (actually hoping for better than that). For a weekend cruise, that would be a lot of motoring for me (almost an unheard of amount of motoring). OTOH, with a quiet and smooth electric engine, I might be more likely to use and engine also.
I would not do a one cylinder diesel. Can you even find one any longer?

I would think an electic output would fit your needs quite nicely. And there are lots of good options out there for this. I almost wish I had gone this route.

[peb]

One other thing to keep in mind with an electric install for a boat that will be kept in the water is the increase in the electric systems needed to support a permament charger that will be plugged in at the marina. Small sport fishing boats often wire the marine plug directly to a mounted charger and leave it at that, but that is certainly not a safe thing to do at a marina IMO. So then you need an AC breaker with a ELCI protection along with some sort of galvanic isolator at a minimu.

[gdallas]

I would think installing any inboard in a boat that never had one is quite a chore, since you would have to bore the shaft tube. Have you looked at any of the pod type electric engines? My build has a full keel and I did not think they would work well, same might be the case with you.

Keep in mind that range increases greatly at lower speeds. My boat is about 25 ft, and weighs in at 5000 lbs approx. It should reach hull speed in calm water at aroudn 3500 watts. I am trying to put in about 120 amp hours of 48V power (lithium), so will have 100 amp hours effective. That only gives me about 1.5 hours at hull speed. But from what I have been told and based on my own research, I think I should get perhaps 6 hours easily at 4 knots of speed (actually hoping for better than that). For a weekend cruise, that would be a lot of motoring for me (almost an unheard of amount of motoring). OTOH, with a quiet and smooth electric engine, I might be more likely to use and engine also.
I would not do a one cylinder diesel. Can you even find one any longer?

I would think an electic output would fit your needs quite nicely. And there are lots of good options out there for this. I almost wish I had gone this route.

So have you fitted a pod drive to a boat with a full keel? I assume it's offset, somehow? I would be interested to know how that works.
'My' boat is full keel, keel hung rudder, traditional plank on frame. But it needs a pretty comprehensive restore/rebuild so I think boring for a stern tube would not add too much cost or complexity . I am a bit more concerned about cutting an aperture in the rudder and losing area.
I think you can still buy a new Yanmar 1GM, but not if you want to keep the fillings in your teeth

[stromborg]

These folks have a couple of reasonably priced packages: https://www.thunderstruck-ev.com/ take a look at their 5 and 10kw kits.
(insert the usual non-affiliation disclaimer here)

I still find the collective hurdles of how many batteries, where they go and how they get charged are the hard ones to get over.

[v10builder1]

When I read the OP's first post about mounting the motor/propeller in an aperture in the rudder, I recalled reading of an installation of a pod motor/propeller completely within the rudder of a reproduction shallop craft. Idea was to insure the craft maintained the look of the 1600's vintage. Additional posts clarify that here, an inboard motor with shaft through hull penetration, and propeller are considered.

Irregardless of the type of engine, locating the propeller in too close proximity to the rudder will adversely affect the efficiency of the installation, more important when the propulsion is electric. As a side note, mounting a pod motor/propeller totally within the rudder is areal hit ti waterflow over the propeller flow envelope, and places thrust loads on the rudder attachment.

[peb]

So have you fitted a pod drive to a boat with a full keel? I assume it's offset, somehow? I would be interested to know how that works.
'My' boat is full keel, keel hung rudder, traditional plank on frame. But it needs a pretty comprehensive restore/rebuild so I think boring for a stern tube would not add too much cost or complexity . I am a bit more concerned about cutting an aperture in the rudder and losing area.
I think you can still buy a new Yanmar 1GM, but not if you want to keep the fillings in your teeth

No, I have not, mine electric motor is installed as a conventional inboard. You are probably right about boring the stern tube hole, lots of people do it. In the "early days" of my build I was scared to do it and just built the boat around the stern tube, its been in place since the beginning.

[stromborg]

Our hosts ran an article on putting a pod motor in a rudder last year, #285 the March/April issue

Also:


https://marineindustrynews.co.uk/sco...tional-rudder/

[leaotis]

I love my 2.2kw Fixed Pod motor with folding prop.
I built a 24v, 50kg Life04 battery that stores 3/4 of the power of a liter of petrol.
Think about that for a minute.

[v10builder1]

Somehow I missed the article stromborg referred to, but +1 on that installation. The ruder is relieved somewhat so as not to interfere with the flow past the prop, and I bet the boat is VERY easy to maneuver in tight spaces. Modest extra load on the rudder attachment.

[kbowen]

Somehow I missed the article stromborg referred to, but +1 on that installation. The ruder is relieved somewhat so as not to interfere with the flow past the prop, and I bet the boat is VERY easy to maneuver in tight spaces. Modest extra load on the rudder attachment.

My setup is refined from the attached photo, but this is basically what I have.. The boat picks up over 1/2 mph when I raise the motor out of the water and handles a whole lot better. And yes it helps enormously under power in maneuvering to turn the motor like an outboard. The downside is that it admittedly looks stupid. This is an 80# thrust Minnkota, 24 volt. I get about 4 mph in a 5600# boat in a flat calm, but it drops very much with a headwind.

Ken

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