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Old 27-05-2018, 22:52   #1
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Electric Drive: Who uses it?

I was curious how many folks on here use electric drive on their powered boats?

There is a guy up at my work who i recently came across with who owns a 41ft defever trawler. He claims he got the boat for nearly nothing because one of the seals on the driveline failed flooding the engine room before they got it out of the water. The motors were needing to be rebuilt he claimed, so he pulled the motors out and replaced them with electric motors from a kit he bought online. He said he uses tesla model s batteries to power the motors.

So my question is how has these worked out for folks so far, ive always been a big electric car fan, i currently daily drive an electric car.

He said his boat has a 12.5kw diesel generator, when he wants to cruise long distance he will power the generator up and run the electric motors at half speed and the output on the generator will provide plenty of power to the circuit to not drain the batteries down while cruising around, he stated he is planning on upgrading the generator to a larger generator in the future, or possibly add an additional 2nd generator onboard for cruising at full speed, but for now he is plenty happy with the speed he can cruise at.

He said when he needs to run full speed, he can crank them up and get about 45-50 miles out of the battery bank before it drops to low to maintain full speed. stated he plans to add additional tesla batteries to the setup when he can source them for a decent price, stated the price of them has nearly doubled since purchasing the ones currently powering his boat.
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Old 27-05-2018, 23:11   #2
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Re: Electric Drive: Who uses it?

Those figures sound about right if you want to cruise in a 41ft trawler at 5 knots or less in calm conditions.



If the use case is low speed running in the local area for day trips it's quite feasible. If you need more power for adverse condition or for longer trips, I'd say it was very inadequate.
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Old 28-05-2018, 04:12   #3
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Re: Electric Drive: Who uses it?

I will second the comments from Stu.

A 12.5 kW generator is about 17 HP. Not a lot of power for a 41 Defever. So in very calm conditions 5 kts might be a reasonable cruising speed with power from the generator but add any wind, waves or current and that goes out the window.

My conclusions from carefully studying the electric option seems like two possible outcomes.

1. A boat that has a very limited range and/or power.

2. A boat with comparable power and range to the original diesel setup but costs double or triple the cost of all new engines and transmissions.

Bottom line, with perhaps a few exceptions, electric is mainly feasible for smaller sailboats that use the engines just to get from the dock to open water.
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Old 28-05-2018, 04:42   #4
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Re: Electric Drive: Who uses it?

I installed a pair of electric pods onto a 30,000 pound 45 foot sailboat. They were made by a company that has since gone out of business. Each pod was fastened to the hull on the exterior, then wiring was run through the hull to a bank of 16 6 volt batteries (two banks of 8, giving a total of 48 volts).

The company sold me on the idea that I could use shore power to charge the batteries (using a 48 volt battery charger), then go out sailing and, while sailing, the motors would freewheel, acting as generators and recharging the batteries. Then, at the end of the day, I would have enough power to get back to the slip and put the batteries back on the charger.

Needless to say, this did not work out. The battery bank had enough power to get me out of the slip and about half a mile past that. Then, I was dead in the water. Without a generator, there was no powering the system and, even if I had had a generator, there was no way to "direct drive" the system. I could only recharge the batteries for an hour or more and then start again, with an ever more decreasing range.

So, the "solution," according to the company (did I mention they eventually went out of business), was to install a diesel generator in the spot that my propulsion engine used to be and then, install a huge transformer to convert 110VAC to 48VDC in order to drive the motors directly. By the time I was done, the cost of installing the motors, the battery bank, the battery charger, the diesel generator and the AC to DC conversion system would have been about twice what a new diesel engine would have been, I would have added about a thousand pounds to the weight of the boat and I would still have to listen to the diesel whenever I wanted to motor.

I finally decided to go back to a diesel engine and scrap the electric idea. I had to have the boat towed to a yard to get it pulled out of the water. When I did so, I discovered both of the electric pods had water intrusion damage and were ruined, which was how I discovered the company had gone out of business.

It seems to me - for what it is worth - that the idea of electric engines works very well for a system designed for it from the get-go. However, you have to ask yourself - what am I giving up and what am I getting. If your goal is to get away from diesel - it isn't going to happen. Not yet, anyway. If your goal is to save money - look VERY carefully at the costs. I use about 500 gallons of diesel a year, traveling up and down the ICW. At roughly $3 a gallon, that equates to $1,500 a year. If I were to pull out my current system and install a larger diesel generator, battery bank and inboard electric engine, I might spend $15,000 and still only cut my diesel consumption in half. That means I would take 20 years to even out the costs. That's a big assumption that the next twenty years would be a wash.
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Old 28-05-2018, 06:24   #5
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Re: Electric Drive: Who uses it?

Quote:
Originally Posted by CaptFrankM View Post
I installed a pair of electric pods onto a 30,000 pound 45 foot sailboat. They were made by a company that has since gone out of business. Each pod was fastened to the hull on the exterior, then wiring was run through the hull to a bank of 16 6 volt batteries (two banks of 8, giving a total of 48 volts).

The company sold me on the idea that I could use shore power to charge the batteries (using a 48 volt battery charger), then go out sailing and, while sailing, the motors would freewheel, acting as generators and recharging the batteries. Then, at the end of the day, I would have enough power to get back to the slip and put the batteries back on the charger.

Needless to say, this did not work out. The battery bank had enough power to get me out of the slip and about half a mile past that. Then, I was dead in the water. Without a generator, there was no powering the system and, even if I had had a generator, there was no way to "direct drive" the system. I could only recharge the batteries for an hour or more and then start again, with an ever more decreasing range.

So, the "solution," according to the company (did I mention they eventually went out of business), was to install a diesel generator in the spot that my propulsion engine used to be and then, install a huge transformer to convert 110VAC to 48VDC in order to drive the motors directly. By the time I was done, the cost of installing the motors, the battery bank, the battery charger, the diesel generator and the AC to DC conversion system would have been about twice what a new diesel engine would have been, I would have added about a thousand pounds to the weight of the boat and I would still have to listen to the diesel whenever I wanted to motor.

I finally decided to go back to a diesel engine and scrap the electric idea. I had to have the boat towed to a yard to get it pulled out of the water. When I did so, I discovered both of the electric pods had water intrusion damage and were ruined, which was how I discovered the company had gone out of business.

It seems to me - for what it is worth - that the idea of electric engines works very well for a system designed for it from the get-go. However, you have to ask yourself - what am I giving up and what am I getting. If your goal is to get away from diesel - it isn't going to happen. Not yet, anyway. If your goal is to save money - look VERY carefully at the costs. I use about 500 gallons of diesel a year, traveling up and down the ICW. At roughly $3 a gallon, that equates to $1,500 a year. If I were to pull out my current system and install a larger diesel generator, battery bank and inboard electric engine, I might spend $15,000 and still only cut my diesel consumption in half. That means I would take 20 years to even out the costs. That's a big assumption that the next twenty years would be a wash.
Very good post!

Thanks for sharing your experience.

Please take a minute to copy/paste your entire post up above to add it to the following discussion thread I curate about Electric Boats. Please include a description of the boat you used, the product you used for power (even if they are no longer in business) and a few photos too.

Electric Sailboats Illustrated Guide to Boats Converted For Sale and Tips
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Old 28-05-2018, 06:40   #6
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Re: Electric Drive: Who uses it?

STORX,

The following discussion thread shows some boats that have been converted. It is focused on Electric Sailboats, but should give you some ideas.
Electric Sailboats Illustrated Guide to Boats Converted For Sale and Tips
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Old 28-05-2018, 06:48   #7
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Re: Electric Drive: Who uses it?

Quote:
Originally Posted by storx View Post
I was curious how many folks on here use electric drive on their powered boats?

There is a guy up at my work who i recently came across with who owns a 41ft defever trawler. He claims he got the boat for nearly nothing because one of the seals on the driveline failed flooding the engine room before they got it out of the water. The motors were needing to be rebuilt he claimed, so he pulled the motors out and replaced them with electric motors from a kit he bought online. He said he uses tesla model s batteries to power the motors.

So my question is how has these worked out for folks so far, ive always been a big electric car fan, i currently daily drive an electric car.

He said his boat has a 12.5kw diesel generator, when he wants to cruise long distance he will power the generator up and run the electric motors at half speed and the output on the generator will provide plenty of power to the circuit to not drain the batteries down while cruising around, he stated he is planning on upgrading the generator to a larger generator in the future, or possibly add an additional 2nd generator onboard for cruising at full speed, but for now he is plenty happy with the speed he can cruise at.

He said when he needs to run full speed, he can crank them up and get about 45-50 miles out of the battery bank before it drops to low to maintain full speed. stated he plans to add additional tesla batteries to the setup when he can source them for a decent price, stated the price of them has nearly doubled since purchasing the ones currently powering his boat.
What is his rationale for the electric engines over diesel? He's running a diesel engine (generator) anyway. Does he anticipate lower costs long term over diesel? Less upkeep? He's certainly not chasing speed.
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Old 28-05-2018, 08:27   #8
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Re: Electric Drive: Who uses it?

Quote:
Originally Posted by skipmac View Post
Bottom line, with perhaps a few exceptions, electric is mainly feasible for smaller sailboats that use the engines just to get from the dock to open water.
In my area, that would only be about 99% of the sailboats.
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Old 28-05-2018, 09:06   #9
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Re: Electric Drive: Who uses it?

Just a historical note here. My Dad was a diesel boat submariner. That whole concept of large battery banks and diesel recharge and propulsion worked very well for generating electricity. Admiral Rickover had the American naval submarine fleet converted over to Nuclear power in the middle of my Dad's career.

I looked at the option multiple times. Spent hours talking with the gentleman at shows. The math still doesn't work out. The idea is seductive. No noise. No pollution. Small motor. Clean energy. Wow!!! Who wouldn't want this set up?

On a sail boat you have sails for your motor. But you don't have room for large battery arrays. If you go lithium ... u have huge money for that. Add solar arrays? Not enough for running an electric. You always have to come back to Dino juice.

If you have ever had a stormy crossing and you have to get to the harbor quickly... wind is blowing in the nose, tide ebbing, wave action building... and u r depending on that battery bank... u r majorly in for a surprise of how fast that bank will be tapped out. It is so hard to understand how much more energy it takes to crawl uphill against wind , current, and waves.
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Old 28-05-2018, 09:08   #10
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Re: Electric Drive: Who uses it?

I also like the idea of electric propulsion but at present it does not look feasible or economic for a main engine replacement. I am however looking at designing and building a tender with about a 4hp inboard electric drive and a solar panel for charging. Will be a way of getting experience with electric systems as well as making a quite instant start tender with no need to mess around with gas cans. Main thing is that it will be a high load carrier displacement design not a light high speed planning boat.
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Old 28-05-2018, 09:19   #11
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Re: Electric Drive: Who uses it?

What's the stock HP for a 41' trawler 120hp vs the 17hp proposed.

If you really only need 17hp, that's going to 17hp diesel will likely be a lot cheaper but I seriously doubt they overpowered it originally by a factor of 7.

Yes, it will move the boat at slow speed on calm days but fight a strong headwind, waves or current and you could quickly find yourself in serious trouble.
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Old 28-05-2018, 09:33   #12
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Re: Electric Drive: Who uses it?

Quote:
Originally Posted by roland stockham View Post
I also like the idea of electric propulsion but at present it does not look feasible or economic for a main engine replacement. I am however looking at designing and building a tender with about a 4hp inboard electric drive and a solar panel for charging. Will be a way of getting experience with electric systems as well as making a quite instant start tender with no need to mess around with gas cans. Main thing is that it will be a high load carrier displacement design not a light high speed planning boat.
I like the idea of electric motors (Torqueedo or similar) for dinghy or tender. Please add yours to the Electric Sailboats thread, whenever you have something to show. While it may not be a sailboat, I think whatever you design will be interesting to readers of that topic.

Electric Sailboats Illustrated Guide to Boats Converted For Sale and Tips
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Old 28-05-2018, 09:38   #13
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Electric Drive: Who uses it?

This is about when in the electric boat threads this video comes up.
Point is to try to show the enormous amount of power even a few hundred Watts is, and how we just really do not have any idea how much power 1gl of Diesel amounts to.
It would take a tremendous battery bank to move a large Trawler very far, and then of course it takes a tremendous amount of energy to recharge that bank. There are losses in charging and discharging, you’ll burn more fuel charging than you will by moving the boat directly. Which is not to say electric doesn’t have its place, just don’t expect much range.

I always love how the electric car people think their cars are zero emission and how they are saving the planet, so I guess they think that electric power just flows out of the plug and no carbon is released to generate it?
https://youtu.be/S4O5voOCqAQ
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Old 28-05-2018, 09:40   #14
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Re: Electric Drive: Who uses it?

If the primary justification is "it costs almost nothing", he's wrong.

1) It takes more diesel per mile to power a generator to make electricity to run an electric motor to turn a propeller shaft than a diesel engine directly coupled to a shaft. With the generator, you lose efficiency with every conversion of energy.


2) In most cases, it costs more per mile in KWH to purchase electricity from a utility or marina to charge batteries for an electric motor than to use diesel in a conventional engine. This might not be true if you are already paying a flat monthly rate from the marina but increasingly marinas are moving to charging by the KWH.
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Old 28-05-2018, 10:58   #15
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Re: Electric Drive: Who uses it?

I went electric when the aging diesel in our Pearson 424 ketch was dying. No regrets. It all depends on how you use the boat. We have enough to get out of the harbor and get the rags up. The motor does indeed act as a generator when under sail, which tops off the bank for our run back in under power. Battery tech is expanding rapidly, so I'm ready for upgrades and have the hardware already installed.
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