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Discussion Starter · #1 ·
I have a 46ft monohull sailboat (1973 Ericson 46) which has a 50hp Diesel. (Beta 50) it runs around 1800rpm with a 2:1 reduction to the shaft drive. So 200ft/lbs of torque at 1400rpm to the propeller. I am going to evaluate that scenario further, the prop is pretty old and could likely be optimized.

She displaces 30,000lbs. That's pretty big. She does have a pretty slippery hull shape and sails well under light wind. I'm thinking this bodes well for power efficiency.
I'm looking at either a full conversion or maybe adding electric as a secondary drive. This depends on how some work on the diesel goes.
I've consulted Thunderstruck and Electricmotorsport. Both came up with the same info - essentially a high voltage pack to drive a single ME-1616 or a pair of 48v packs driving a pair of ME-1616s to get the 20-30KW of power needed to drive the boat.

Why not 48v? Most boat builds would just build a big 48v pack and run inverters, house power, etc off that.
I am mostly done building a 24v system for that. I have a 5000/24/120 Victron Quattro inverter, 3x 100/20 solar controllers that each get a 530w panel, cerbo gx, OrionBMS jr talking can to the Cerbo etc. The battery is a 3s16p of 304Ah EVE Lifepo4Po cells. That's around 24Kwh there.
I figure I'll make the traction pack able to charge off the house pack, but probably using inefficient DC->AC->DC charging. I may explore some DC-DC chargers, but they really just don't tend to build them for high amperage.

So far, I've purchased a ME-1616 since most places are back ordered and I found a few in stock.

Things to solve:
Power transmission - I need at least a 2:1 if not a 4:1 reduction. High voltage likes high RPM in my experience and I need the 4:1 to get the torque numbers up.
Thunderstruck has a belt drive option but I don't have details on what belt that's based on. This is a lot of power....

Controller selection:
I figure I'll have one of two vendors setup the controller for me. Both Thunderstruck and Electricmotorsport are willing to do that. So it's sevcon vs kelly.
I'm going to sort out battery options first to account for final voltages, etc.

Battery:
Honestly, probably LifePO4 for this. I'm polling in the battery forum for other suggestions. I'm eyeballing custom 18650/26650 packs as well as EV pack repurposing.
Polling in the Battery forum on this bit.
I figure I'd like to go for at least 20kwh, maybe up to 40kwh.

BMS:
I'm leaning toward OrionBMS. I've started using these in my solar installs (Boat and RV) and figure it's easier to just use the same style/brand in all my systems.

Hybrid vs EV vs EV+ Generator:
So, I have a misbehaving diesel. I'm going to pull it and figure out what's happening, but it's entirely possible I may decide it needs to go.
If it's recoverable, I'll probably keep it for the range. Buuuut, it would be hella cool to charge up my traction pack using regen off the big motor, and then be able to switch to electric for an hour or two and back.
If the big engine goes, then I'd probably look at adding a newer diesel generator. The boat had one but it was removed at some point.

I gotta say, the more I consider the hybrid approach, the more I'm really, really digging the idea. The option to motor off of solar/hydro gen power would be cool and then having the ability to motor on diesel as needed... I really, really like this idea. Especially given the size of my boat. It's not really trivial to add an outboard for aux power...
 

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Power transmission - I need at least a 2:1 if not a 4:1 reduction. High voltage likes high RPM in my experience and I need the 4:1 to get the torque numbers up.
Thunderstruck has a belt drive option but I don't have details on what belt that's based on. This is a lot of power....
It's not clear what Thunderstruck uses, but it's small. A good choice (but certainly not the only one) would likely be a Gates Poly Chain GT Carbon Belt Drive; Gates provides an entire drive design manual to help with selection.
This is not trivial power, but it is not much compared to what the right type and size of belt can handle.
 

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Discussion Starter · #3 ·
Minor progress, I've decided that I am going with Tesla modules for this. I think 5 in series will be the best scenario.
By going with 5, the max charge voltage will be 126v, the controller maxes at 125 so I'll limit charging to say, 115-120v or so. Looking at power ouputs...
Ideal Amp draw based on Motor output vs pack voltage120v ([email protected])100v (5s @20v, [email protected])90v (5s @18v/ea)
25Kw208A250A278A
20Kw167A200A222A
15Kw120A150A167A
10Kw83A100A111A

This table really highlights why going 5s on the the tesla packs is worth it

The modules should be much happier when run at under 1c - aka around 200-225A on those units.
I will be water cooling using a closed loop with a heat exchanger. This should keep the system pretty happy.
To avoid pocket book pain, I'm going to start with a single set of 5.
I think if I retire the main diesel, I'd go ahead and run 5s2p and get that draw down to .5c per string.
 

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Discussion Starter · #4 ·
I am still debating sevcon vs kelly. I need to read more.
Thunderstruck got points with me on the kelly since they provided the actual part number vs Electricmotorsport (who was great on the phone but provided very limited details on the build sheet they sent me.)

My ME-1616 arrived today. It's... small. Really, for the size I am impressed by the claimed efficiency numbers and output. Dang. Now I kinda want another one to shove into a 4x4 build.

Now, on the cooling front. I need to water cool the motor and plan to water cool the battery packs. I am thinking of combining these into a single closed loop system with a raw/salt water heat exchanger:

Outlet from heat exhchanger ---> Pump ----> Battery packs ---> Motor ---> HX inlet.
Ocean--> Sea Strainer ---> Raw water pump-->HX-->Ocean

Alternatively I am looking at two closed systems with two pumps, two HXs and either one or two raw water pumps.

Sorry for a lack of specs here, I need to figure out what sort of BTU I'm dealing with to spec out the hardware.
 

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I have a 46ft monohull sailboat (1973 Ericson 46) which has a 50hp Diesel. (Beta 50) it runs around 1800rpm with a 2:1 reduction to the shaft drive. So 200ft/lbs of torque at 1400rpm to the propeller.
...
I've consulted Thunderstruck and Electricmotorsport. Both came up with the same info - essentially a high voltage pack to drive a single ME-1616 or a pair of 48v packs driving a pair of ME-1616s to get the 20-30KW of power needed to drive the boat.
...
Power transmission - I need at least a 2:1 if not a 4:1 reduction. High voltage likes high RPM in my experience and I need the 4:1 to get the torque numbers up.
An ME-1616, according to the specs published by ElectricMotorsport.com (since Motenergy doesn't appear to provide specs) can only produce 134 Nm peak, using 550 A, and can only handle 250 A continuously. That implies that the continuous 250 amps will produce about 61 Nm (45 lb-ft) of torque, from stall to about 3100 RPM (since that's the speed required to produce 20 kW @ 61 Nm) at the voltage corresponding to 20 kW continuous power capability.

To produce about 200 lb-ft of torque to the prop, more than 4:1 gearing will be needed, so the motor will run at more than 5600 RPM when the prop is at 1400 RPM. If the motor can sustain that torque at that speed (and if it can run continuously at that speed without disintegrating), the combination would be 36 kW.
 

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Discussion Starter · #7 ·
@brian_ So yeah, that's at 48v as I understand it. I've had two options floated at me: A single ME-1616 at 96v or dual ME-1616s at 48v. In fact, ElectricYacht has suggested as much as dual ME-1616s at 72v.
I'm leaning toward a single unit at 100v+ to get reasonable output.

That said, this is still a slow burner project for me...
But I did pick up three Tesla S modules for the parts pile. Just a couple more to get me to an actual pack. I suppose in the meanwhile I can use them as a powerwall.

I'm planning to deal with my diesel issues (or at least get started on it) in a couple of weeks.
With that in mind I'm more and more committed to the idea of a diesel electric hybrid.

It's going to come down to how I arrange the transmission system. At this point, I'm leaning toward adding a pulley/sprocket to the output of the diesel transmission to the prop shaft. This would leave the electric motor turning all the time unless I add some sort of clutch.

Using that kind of take off seems really ideal for generating some serious power off the diesel.
It would eliminate the need for a generator, but allow for either electric or diesel motion.

I've been reviewing others usage of electric motors, and they tend to run easy on them - rather than say a full on 1400rpm output at the prop, they appear to be more of 800-1000rpm people to keep the draw down. I've also seen notes about how running regen in bigger seas is helpful for calming the boat down - which is very interesting.

With that I'm still hunting down belt drive information. I'm leaning toward a chain on the drive to the prop shaft - why? The challenge of replacing a belt around the propshaft... Maybe it's easy, I'll mess with it. Because of what I have in mind, this will clearly require some custom drive engineering.

As a backup plan, I discussed running a pair of ME-1616s with Thunderbolt EV in case I retire my diesel. Their impression was that typically one motor does most of the work and you end up with premature wear. I wasn't looking for it, but I think this is what happened to the dual motor system on The Rigging Doctor's boat.
 

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It's going to come down to how I arrange the transmission system. At this point, I'm leaning toward adding a pulley/sprocket to the output of the diesel transmission to the prop shaft. This would leave the electric motor turning all the time unless I add some sort of clutch.

Using that kind of take off seems really ideal for generating some serious power off the diesel.
It would eliminate the need for a generator, but allow for either electric or diesel motion.
That's the classic parallel hybrid, but you would need an engine clutch for electric-only operation.

With that I'm still hunting down belt drive information. I'm leaning toward a chain on the drive to the prop shaft - why? The challenge of replacing a belt around the propshaft... Maybe it's easy, I'll mess with it. Because of what I have in mind, this will clearly require some custom drive engineering.
The drive belt manufacturers publish helpful design guides - it's worth checking one out.

As a backup plan, I discussed running a pair of ME-1616s with Thunderbolt EV in case I retire my diesel. Their impression was that typically one motor does most of the work and you end up with premature wear. I wasn't looking for it, but I think this is what happened to the dual motor system on The Rigging Doctor's boat.
I'm not a fan of using two motors instead of one properly sized motor, but if two motors are driving the same shaft (so they're matched in speed) and one is doing most of the work, I would think that the controllers are not setup properly.
 
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