45' solar catamaran

My boats are designed to capture the sun as early as possible so my MPPT’s can start their charge cycle as early as possible, and so that my batteries are fully charged by late morning and the power I used during the night is replenished before I start to draw on them again and or pull anchor and motor or sail away.

What you describe as marginal gains for only a small part of the day is exactly the opposite in practice with the way I use my boats.

Seems you are already making things far more complex than they need to be by using a pair of Leaf motors to power a non planing hull that is going to be down on its lines when all is said and done, when you could easily push that boat to its hull speed with a pair of less complicated smaller 48V motors with standard controllers and basic components.

The biggest limitation with solar electric boat design is limited space for panels, so the more effective you can make them, the better, and if you can reduce windage both while under way and in bad weather events, and create more headroom and an improved view when at anchor, then IMO it’s worth it.

 

Sure I would like to see your set-up.
But marginal gains is what I've experiment, read and see since many years.

To me Leaf motor at 48V is as simple than standard/basic components. They are simply cheaper, easily watercooled, rugged and can be direct drive (no belt, pulley or gearbox to have trouble with).

You are right and I would like to do something wise. Do you have example or drawings?
To me, Keep It Simple Stupid is key when I design, so I don't see more simple and reliable than a large, flat surface with no moving part.

 

I’m curious, how many examples of boats have you found successfully using Nissan Leaf motors running on 48V for propulsion?

Or are you just seeing chatter online from people who have managed to get Leaf motors to spin up on a test bench on low voltage using third party components?

I completely understand the appeal of using the Leaf system and it’s something I’ve suggested to many who have frequented this forum, but those people weren’t fighting buoyancy and weight issues, and mostly were looking to repower planing hulls.

I agree with your design philosophy, but if adding some complexity results in a variety of benefits across the board, then it is worth serious consideration and might be worth the effort.

 

None! People simply buy crappy chinese motor or pay over priced for ''real'' marine motor like Bellmarine, Epropulsion, Oceanvolt, Torqeedo, etc.
Not everyone can see the high value/low price in a high quality used EV components.

I've succesfully tested it myself and plan to do further tests outside the boat in order to choose proper propeller. Here: Electric inboard motor, my journey to find proper motor https://www.boatdesign.net/threads/electric-inboard-motor-my-journey-to-find-proper-motor.69574/

Yes, this is still concerning in my case. I'm still unsure what is the problem if my Cat sit 4 inch deeper in the water and the bridgedeck clearance pass from 25'' to 21''.
I'm clearly not designing an ocean crossing Cat, so what can be hughly problematic if bridge deck is a bit lower?

 

Can it be a good idea to rebuild our cabin in Aluminum?

It seem strange to me to have an aluminum cabin with wood epoxy hulls, but I highly prefer working with aluminum and if it's a bit lighter, it's excellent for our project.
Pictures and 3D P.8 / post 112 to 120.
Any thought about this?

 

My point about the use of Leaf motors in boat applications had to do specifically with running them at such low voltage, not that there aren’t people using them. People are, but they are running them at much higher voltages in order to take full advantage of their performance and efficiency properties.

 

I perfectly understand.
Sure no body is interested to have 10 kW of output from the Leaf motor when it can output way over 100 kW at high voltage (read here: full advantage of their performance and efficiency properties).
But I'm interested because this motor can output serious torque at low rpm and that can allow me to use it in direct drive application. No gearbox, no belt/pulley. Just simple and reliable direct drive.

 

I'm lost, how is this drive supposed to work as a hybrid ?

 

I bet you are talking about the picture below implying the belt/pulley.
I'm still torn between:
1-Small diesel driving prop and acting as generator + 100 kWh battery and 2 Leaf motor (essencially what you can see in picture).
2-Generator + 170 kWh battery and 2 direct drive Leaf motor.

 

I don’t understand why you wouldn’t just use the Nissan Leaf gearbox which is already setup for a split differential and has bearings that can handle thrust load instead of using belts and pulleys and turning one motor around backwards in order to couple it to your diesel motor.

The gear reduction will help with your plan for turning an aggressive prop at low RPM, but of course you’ll need to get the motors to spin up to the required RPM which means upping the voltage.

With the split differential gearbox, one side can drive the prop shaft and the other can be coupled to the diesel, even decoupled via a clutch if you desired.

The gearbox is a very simple and efficient design and would eliminate potential misalignment and vibration issues while providing solid mounting of the complete assembly.

Did you get the gearboxes with your motors?

Have you taken them apart to see how they work?

 

Shaft rpm. With 7:1 ratio, output speed can be really low.

Yeah! Could be an idea if I was planning to go 360V battery. It's not the case right now.

Differential are not design to spin only one side for more than few second and not with a big rpm difference.

Planty of video and pictures online. Example: Nissan Leaf transmission - openinverter.org wiki https://openinverter.org/wiki/Nissan_Leaf_transmission
It's not the plan as I'm RPM limited for at the moment, but I like brainstorming about potential solution. Thanks.

 

You consider serial vs paralell hybrid.

Btw. Kobben's are a serial hybrids . And most of diesel trains .

 

Yeah! And I'm more torn than ever because today I realized something.
I don't like serie hybride because of lost (diesel - AC current - AC charger - 48V DC) and I don't like parallel because of the belt/pulley implied.
But I realized that I could build a 48V DC generator (diesel - 48VDC) with a motor I already have at home (Motenergy ME1507)...

Ummm!I have to think about all this deeply.

 

That 48V generator (A) start to make a lot of sense to me.
Then I can ditch the belt and pulley solution (C) and have 2 really simple direct drive identical propulsion assembly (B)

 

We took time to measure more precisely the hulls of our Cat. Water line is 41' long and based on water displacement, the Cat should weight around 7.6 tons (16700 lbs).
Each inch deaper in the water move 432 kg (950 lbs) of water.
Center of buyancy is 41.5'' more in the rear based on water line, so 7' more in the rear based on total boat lenght.
Over 45', that mean center of buyancy is 19' from the back and 26' from the front.