Star-Lord, Electric Trawler Conversion

[syjos]

I have not done a full research of the diesel/electric conversion since my Lehman keeps chugging along.

I envision charging batteries at a dock, cruising until the batteries are 1/2 depleted and firing up a large generator to replenish the batteries while still cruising. Recharge at the next dock or recharge with generator at anchor.

This is all supposition and some guess work for fun.

I've done some simple weight calculations using lead acid batteries and it may be doable. Removing the large fuel tanks and replacing them with smaller tanks in addition to the weight saving from the engine and transmission should offset the battery bank and larger generator. I have not explored lithium batteries either, new or used, due to the costs but they are coming down in price. And used components from automobiles are becoming available.

Cruising speed could be reduced by 1 to 2 knots to extend range.

I'm not expecting a 100% battery ride but possibly a reduction in fuel usage.

[Fletcher500]

There is nothing I can add on the topic, but I have enjoyed following along. An interesting topic. You will get some wonky comments, which are expected on any forum, but sounds like you already know that. Keep us posted as you progress through the process.

[hpogue123]

Originally Posted by Nomad Willy

syjos,
Did you see/read the article on PMM about 8 years ago on a Mainship? I have no personal interest in all electric propulsion but I’d really like the diesel/electric option. I loved the high and instant torque in the harbors. Also single engine twin screws has some distinct advantages. And I think as a twin engine diesel/electric twin engines of different sizes would offer even more interesting advantages.
With DE (diesel electric) can one use the propulsion batteries for domestic power? I’m probably showing my grey hole in electric propulsion but ??

I remember several years ago at the Boston Boat show there was a ~40ft diesel/electric boat that looked great except the cost. Anyone remember the brand?
I was mainly a sailor then so only interested as an engineer. It could run from batteries or direct drive from diesel or diesel to gen. to recharge. Very interesting but big bucks. If I remember correctly, I think it had a 10 mile range on batteries.

[twistedtree]

Originally Posted by hpogue123

I remember several years ago at the Boston Boat show there was a ~40ft diesel/electric boat that looked great except the cost. Anyone remember the brand?
I was mainly a sailor then so only interested as an engineer. It could run from batteries or direct drive from diesel or diesel to gen. to recharge. Very interesting but big bucks. If I remember correctly, I think it had a 10 mile range on batteries.

Not a Greenline?

[hpogue123]

Yeah that's it. Hear anything from any owners?

[Donsan]

Have you given any consideration to adding a frame or hard top over the aft cabin and adding additional solar panels?

[hpogue123]

I have 15kw (50 x 300w LG panels) on my house and 1200w on my camper (which adds to the house when I'm not using it). I plan on adding 1800w between the bimini top and sundeck on the boat from remaining panels. Check out pallet the pricing on panels, it really cuts the costs.

[Nomad Willy]

Originally Posted by hpogue123

Yeah that's it. Hear anything from any owners?

This wasn’t the boat I was thinking about on PMM. It was modern like 80’s/90’s styling. I can dig it up when I have more time. I have a pile of PM magazines but it will take time to find. May have been direct diesel-electric w/o batts involved. Like a diesel/electric locomotive.

[Star-Lord]

Originally Posted by Donsan

Have you given any consideration to adding a frame or hard top over the aft cabin and adding additional solar panels?

Quick sketch of my solar panel plans.
4 panels aft with 6'6" head room and bench seating.
I want to make this strong enough to hang a dinghy.
9 panels above the saloon. 2 more forward.
Total of 15 panels.
I would love more panels and would love to point them at the sun.

However this simple fixed layout is my working plan right now.
It will change a 100 times and end up were I started I'm sure.

This layout gives me good walk around deck clearance without all the panels too high and top heavy.
I am going to make another helm station with joystick control above the aft cabin shown.
The whole thing needs to fit under an 11' fixed bridge in my neighborhood.



Thanks
Jeff

[Star-Lord]

Originally Posted by hpogue123

I have 15kw (50 x 300w LG panels) on my house and 1200w on my camper (which adds to the house when I'm not using it). I plan on adding 1800w between the bimini top and sundeck on the boat from remaining panels. Check out pallet the pricing on panels, it really cuts the costs.

very nice

[Star-Lord]

This weekend I uncovered a serious blister and delamination problem with my hull. Right now I am planning to try and fix the situation. However, once I have all of them exposed I may need to rethink this donor boat. I am not happy right now. I don't know how bad it is yet.

I think I got one of the Gulfstars with the poor quality layer bonding.

[Star-Lord]

Here is a picture of the Prius transmission that I have working.
The center shaft is where the internal combustion engine (ICE) would connect in a Prius.

The axle CV joint is lower left and is connected internally to the electric motor with a 4.11:1 gear reduction.
This is where I plan to drive the boat shaft.
I will use the Prius axles via a rigid mounted thrust bearing to the propeller shaft.

The transaxle is all aluminium, liquid cooled and filled with lubricating oil.

[twistedtree]

Originally Posted by Star-Lord

Here is a picture of the Prius transmission that I have working.
The center shaft is where the internal combustion engine (ICE) would connect in a Prius.

The axle CV joint is lower left and is connected internally to the electric motor with a 4.11:1 gear reduction.
This is where I plan to drive the boat shaft.
I will use the Prius axles via a rigid mounted thrust bearing to the propeller shaft.

The transaxle is all aluminium, liquid cooled and filled with lubricating oil.

Attachment 89571

Is the differential part of that same assembly, and if so, how do you lock it? I'm presuming you will only use one of the output shafts, buy maybe not?

[Star-Lord]

Originally Posted by twistedtree

Is the differential part of that same assembly, and if so, how do you lock it? I'm presuming you will only use one of the output shafts, buy maybe not?

The differential is inside. I will lock it in place. I have couple of ideas.
The transaxle is not too difficult to open and modify.

I will actually remove all of the heavy internals and just use the light weight shell during my motor mounting fabrication and moch up in the boat.

[twistedtree]

Originally Posted by Star-Lord

The differential is inside. I will lock it in place. I have couple of ideas.
The transaxle is not too difficult to open and modify.

I will actually remove all of the heavy internals and just use the light weight shell during my motor mounting fabrication and moch up in the boat.

Sounds good.


And speaking of the gear box, is it even necessary? Could you get the desired power with a direct drive from the motor to an appropriately sized prop? Or maybe the gear box is a convenient engine mount?

[Star-Lord]

good article.

https://www.agbm.fr/attachment/387917/

[Star-Lord]

Originally Posted by twistedtree

Sounds good.


And speaking of the gear box, is it even necessary? Could you get the desired power with a direct drive from the motor to an appropriately sized prop? Or maybe the gear box is a convenient engine mount?

The gear reduction seems like it might be the perfect ratio needed for maximizing available power of the motor.

The electric motor stator and rotor bearings and all the gear reduction components are all part of the same assembly housing.

You could save weight by removing the gear reduction components and making a direct connection to the motor via the engine center shaft. In this case you would be at 25% of the available torque and spinning the motor very slowly.

[Ski in NC]

Make sure the output shaft you use can handle prop thrust load. In a car the axle shafts don't apply much thrust load. Some differential support bearings can take thrust as a component of gear loading probably makes thrust. But you want to check that.

Gear ratio probably in the "ballpark" for what you are doing. And e-motors are not picky with loading and rpm, to a point.

[Star-Lord]

Originally Posted by Ski in NC

Make sure the output shaft you use can handle prop thrust load. In a car the axle shafts don't apply much thrust load. Some differential support bearings can take thrust as a component of gear loading probably makes thrust. But you want to check that.

Gear ratio probably in the "ballpark" for what you are doing. And e-motors are not picky with loading and rpm, to a point.

I am adding an extra rigidly mounted thrust bearing to the propeller shaft mounted to the hull.
No thrust load on the automotive CV joints is expected.

[stubones99]

I happened to see a charter cat conversion video series about a boat named Top Secret where the gentleman had a off-charter boat that needed a complete refit and he chose to go electric instead of traditional diesel propulsion. He goes into the hows, why's and how much and how fast of the result boat.

https://www.youtube.com/watch?v=o6kOvjS1ytE

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

He chose a Volvo DC genset which would not have been my choice, but has diesel to recharge the batteries (Not an AC genset, but diesel to DC genset.

He used oceanvolt propulsion drives, and said that he actually needs two, not four, but didn't know that at the time. The MFG said 4 and he went with it, but turns out the speed difference is slight, but power draw is double.

I am not sure a prius drive system would be optimum for a boat, since they are on fairly light load most of the time, where a boat is under fairly constant heavy loading.

I liked the open and honest comments of the owner of Top Secret, telling what worked and what didn't and even some unexpected benefits of the conversion.

There was an older sailboat around Merritt Island a few years ago that had two banks of panels mounted from the stub mast and adjusted with electric actuators to allow him to run completely electric, but it wasn't something you'd want to look at for long... effect perhaps, but fugly...