Star-Lord, Electric Trawler Conversion

Hello, this is my first post on this forum.

I just bought this derelict 1972 43' Gulfstar with plans to convert it to electric drive.

I made a video walk through of the boat and discuss some of my plans.

My first milestone is to get the engines pulled, remove the fly bridge and refinish the bottom side. Then tow the project to my dock where the electric drive conversion will begin.

I have some blister repair, glass over the exhaust ports, some through hole fittings to replace.

I hope the 8kw diesel generator on board is salvageable.

I will then purchase two wrecked Toyota Prius for drive train and electrical parts. I have some experience hacking the motor inverters with some EV projects.

It is conceivable that I could have a diesel electric proof of concept for very little money not counting my time.

If all goes as planned then I will install the solar array. I have a plan to fit 15 300W panels for 4.5kW of solar. The solar may also be used to power my home when the boat is docked.

Last step in the project will be a large battery bank. Probably over 100kwh of tesla battery modules. The batteries will likely be the most expensive part of the project but I have a few options.

P.S. I own and Tesla and Chevy Volt and I am a hard core electric vehicle enthusiast. I may be a bit delusional but that is my style.

Thanks
Jeff

Sounds like a fun project. I look forward to following. And once you are done and running for a while, I’ll be interested to hear where and how you see an electric boat like this fitting in the market. What sort of usage is practical and/or advantageous for electric

Fun project for you, but if you're going through all that effort how much more would it really be to convert it to a single engine? With electric drive and batteries you need to conserve every single watt possible.

Greetings,
Welcome aboard. Ambitious project, to be sure, and I wish you well. Oh...It's saloon not salon. (Pet peeve of mine)

Interesting project. I think the difficulty in a boat has always been energy. 100 kwh is about the amount of energy in 10 gallons of diesel. With a conversion efficiency of 35% vs near 100% for electric, call it 30 gallons.

The following hybrid was designed by a one time poster, Reuben Trane. It has been on the market for several years now. It has a 6KW solar array and gets a little over 25NM per day on its batteries. Don't mean to be discouraging but most boat owners need an exit strategy for when they move on to their next boat or house.

https://www.yachtworld.com/boats/2009/island-pilot-dse12m-hybrid-2695424/?refSource=standard listing

predictions?

How long will it take to deplete the batts?

How fast will the boat go with exhausted batts on the gen set alone/

Not sure on range or practicality yet but I have seen other designs and try to understand their compromises and shortcomings.

Rueben Trane was mentioned above. One of his posts or videos that I saw he mentioned 8.5kwh for 1.2GPH diesel at equivalent boat speed. I think 5 or 6 knots.

Napkin math shows 8.5kW with 100kWh battery at 6 knots gives 70NM with single charge of battery.

There is also an 8kW diesel generator (hopefully works) and a 300 gallon diesel tank. Not going to calculate the range but would be a lot.

Add in 4.5kW solar array and I might be able to run the air conditioner also.

I will not be discouraged. I will not put diesel engines back in. A floating solar array at my dock for powering my home if nothing else.

Jeff

Good luck and welcome aboard.

There was question about converting to single engine.

Interestingly I would rather keep the twin props and get rid of the rudders. I have never operated a boat of this size but I assume you can create rotational thrust vectoring using tank steering of the two shafts. Electric motors can infinitely adjust their thrust forward and reverse with ease.

If I only had tank steering and no rudders, I would not expect the operator to fiddle with two levers. I would build an intuitive drive by wire joystick that would vary the individual motor thrust including forward and reverse to steer and maneuver the boat.

I already took the rudders off for repairs. I would love to not put them back on. I would like to better understand the responsiveness of steering such a boat using only motor thrust vectoring.

The boat yard guys think leaving the rudders off is bad idea even if for the ease of towing control. I agree with the towing aspect or loss of one motor at sea but I am not convinced that tank steering wouldn't work.

The rudders are huge and must create a significant amount of drag.

Jeff

Greetings,
Mr. SL. I agree with the drag aspect of the rudders but the fact remains loss of one electric motor would have you going in circles. Perhaps a large single rudder in line with the keel for emergency counter steerage? Less drag, I imagine. Needn't have a wheel for control, set the rudder angle for a straight course electronically and call for assistance when close to shore. Just throwing stuff out there.

I think you would regret leaving the rudders off, when motoring with the waves, the tendency of a boat to yaw can be so substantial that it would likely require one motor to operate in reverse which would really impact efficiency. As a general rule, trawlers are given just enough rudder size to have adequate control, oversizing them hurts efficiency and increases cost so manufacturers rarely oversize them. If the boat has large rudders, it is because it needs them to retain control running with the waves. Do you have any experience running a similar vessel in a following sea?

Star-Lord said:

Not sure on range or practicality yet but I have seen other designs and try to understand their compromises and shortcomings.

Rueben Trane was mentioned above. One of his posts or videos that I saw he mentioned 8.5kwh for 1.2GPH diesel at equivalent boat speed. I think 5 or 6 knots.

Napkin math shows 8.5kW with 100kWh battery at 6 knots gives 70NM with single charge of battery.

There is also an 8kW diesel generator (hopefully works) and a 300 gallon diesel tank. Not going to calculate the range but would be a lot.

Add in 4.5kW solar array and I might be able to run the air conditioner also.

I will not be discouraged. I will not put diesel engines back in. A floating solar array at my dock for powering my home if nothing else.

Jeff

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BoatDiesel.com has some calculators that you might find helpful. I played around with a 40' waterline displacement boat weighing 40,000 lbs. I'm thinking that should be pretty close to what you have. 8.5kw at the flywheel will drive the boat 4.4 kts. 100kWh will last for about 11 hrs allowing for a very small conversion loss (probably too small), so range should be 45-50 nm.


Solar recharge at 4.5kw will take about 23 hrs of full sun and full output. With a typical 5hrs of full sun equivalent available per day from solar panels, you are looking around 5 days to recharge before you can go another 45-50 nm. And that assumes no house electric loads, which of course won't be the case.


You could of course run the generator to recharge and/or power the electric drive, but that will always consume more fuel than direct diesel power.


You might want to run some of these numbers to characterize what the boat will do. It's all pretty predictable. Now I'm a firm believe that "because I want to". or "because it will be fun" is all the reason anyone needs to take on a project. Practicality doesn't have to factor into it. Heck, that's sort of the definition of boating, isn't it? But I think it's always good to have an idea what you might expect as an outcome.

Gdavid said:

I think you would regret leaving the rudders off, when motoring with the waves, the tendency of a boat to yaw can be so substantial that it would likely require one motor to operate in reverse which would really impact efficiency. As a general rule, trawlers are given just enough rudder size to have adequate control, oversizing them hurts efficiency and increases cost so manufacturers rarely oversize them. If the boat has large rudders, it is because it needs them to retain control running with the waves. Do you have any experience running a similar vessel in a following sea?

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No following sea experience but I can imagine trying to surf down a wave without a rudder could be dangerous.

Thank you

twistedtree said:

BoatDiesel.com has some calculators that you might find helpful. I played around with a 40' waterline displacement boat weighing 40,000 lbs. I'm thinking that should be pretty close to what you have. 8.5kw at the flywheel will drive the boat 4.4 kts. 100kWh will last for about 11 hrs allowing for a very small conversion loss (probably too small), so range should be 45-50 nm.


Solar recharge at 4.5kw will take about 23 hrs of full sun and full output. With a typical 5hrs of full sun equivalent available per day from solar panels, you are looking around 5 days to recharge before you can go another 45-50 nm. And that assumes no house electric loads, which of course won't be the case.


You could of course run the generator to recharge and/or power the electric drive, but that will always consume more fuel than direct diesel power.


You might want to run some of these numbers to characterize what the boat will do. It's all pretty predictable. Now I'm a firm believe that "because I want to". or "because it will be fun" is all the reason anyone needs to take on a project. Practicality doesn't have to factor into it. Heck, that's sort of the definition of boating, isn't it? But I think it's always good to have an idea what you might expect as an outcome.

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I will definitely check out the website.
I think my boat is in the 20,000# range.

The battery capacity is very scaleable. About $250 per kwh for salvage EV batteries right now but getting cheaper.

I have more than enough space for as many batteries as I can afford.

I am also intrigued by the kite sails pulling boats.

I want to have some level of expectation but I am in the "because I want to" camp. Traditional methods are just too traditional.

I see people try to calculate the fuel cost savings for an electric car. All I can think of is that they have never driven one. It is simply more fun. It is like trying to cost justify you bass boat on the number of fish you catch.

Interesting and fun project. I look forward to following your progress. It's entirely possible you could come up with something innovative. For whatever it's worth, I agree with the others about keeping at least one rudder.

What’s the matter w the Gulfstar as it is?
Fuel efficiency w get home reliability and maneuverability on port.
Slow down some and 1gph would be in the bag.

Electric? Just a huge expense and human effort.

Greetings,
Mr. NW. Re-read Mr. (Saint) tt's post #13. "..."because I want to". or "because it will be fun" is all the reason anyone needs to take on a project."

It appears to me that Mr. SL is committed to this experiment expense and/or human effort be damned. It's the challenge. You know. Sorta like flying ultra-lights. Less than useful as transportation, lots of fun participating.


Personally, I don't think either the battery or the solar cell technology is up to the task at this point BUT, one never knows WHAT will come out of Mr. SL's efforts. Go for it Mr. SL!

Nomad Willy said:

What’s the matter w the Gulfstar as it is?
Fuel efficiency w get home reliability and maneuverability on port.
Slow down some and 1gph would be in the bag.

Electric? Just a huge expense and human effort.

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Leaving "as is" is not an option.

Determining the amount of expense and effort is key. Finding ways to reduce the expense and effort is inevitable.

My first reduction in expense is that I am using salvaged Electric Vehicle components from wrecked cars. About 1/10 the cost of off the shelf motors, inverters, and solar charge controllers.

I own a hybrid car, all electric snow blower, lawn mower, leaf blower, weed whacker; I am also a train buff and am used to electric engines in all those trains - most don't know that those engines hauling long consists are electric but they are. We even have a guy here who plans to run a commercial aircraft from Vancouver Island to Vancouver using all electric.

You will spend as much time waiting for your batteries to charge as you will cruising. And are you always going to find a place where you can fill up in the summer when other boats are vying for guest slips. An electric motor run my a generator full time, yes - that's what the large commercial freight engines use.


But for a boat your size, nope! Not all electric. I agree with the above when it comes to power, range, and enough energy to get you back in if you get out into a blow. Or enough range to go anywhere without having to "fill up" again. Its kind of like the early all electric cars where you could only go something like 30 miles; they didn't sell well. You get full points for thinking outside the box, but sometimes there are good reasons for people living inside the box.

If you go to a single engine which you might want to seriously consider due to the cost of replacing two engines, I'd definitely add a bow thruster.

rsn48 said:

I own a hybrid car, all electric snow blower, lawn mower, leaf blower, weed whacker; I am also a train buff and am used to electric engines in all those trains - most don't know that those engines hauling long consists are electric but they are. We even have a guy here who plans to run a commercial aircraft from Vancouver Island to Vancouver using all electric.

You will spend as much time waiting for your batteries to charge as you will cruising. And are you always going to find a place where you can fill up in the summer when other boats are vying for guest slips. An electric motor run my a generator full time, yes - that's what the large commercial freight engines use.


But for a boat your size, nope! Not all electric. I agree with the above when it comes to power, range, and enough energy to get you back in if you get out into a blow. Or enough range to go anywhere without having to "fill up" again. Its kind of like the early all electric cars where you could only go something like 30 miles; they didn't sell well. You get full points for thinking outside the box, but sometimes there are good reasons for people living inside the box.

If you go to a single engine which you might want to seriously consider due to the cost of replacing two engines, I'd definitely add a bow thruster.

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I hear you
However I know of fully electric cruise ships that are in development.
The battery is gigantic.

Big battery + small generator + solar array just might work.

Greetings,
Mr. SL. Have you ever considered a fuel cell? https://blog.ballard.com/fuel-cells-marine-vessels

PMM did an article on a converted Grand Banks, I think, from diesel to hybrid, generator driving 2 electric motors. Advantages were more room in engine room and the torque in electric motors comes on at extremely low RPMs. It was going to be the big new thing, however it apparently went without a trace. Never really heard about it again. You might look the article up and read it.

Comodave said:

PMM did an article on a converted Grand Banks, I think, from diesel to hybrid, generator driving 2 electric motors. Advantages were more room in engine room and the torque in electric motors comes on at extremely low RPMs. It was going to be the big new thing, however it apparently went without a trace. Never really heard about it again. You might look the article up and read it.

Click to expand...

So goes the frontier ...
many say it was the frontier that made America great.
All this electric stuff from batteries is pop energy. It’s hard to say how long it will remain popular but it will melt down eventually. I was up to —- in UL aviation in the 80’s and it definitely was a pop fad. When was the last time you saw an UL? I’m an old man that like old things ... but only certain things. Old furniture from the 50’s .. NO. Cars from the 50’s .. big yes. Ect ect. But I like engines so I almost need to dislike solar and motors. Baugh humbug basically. But like I said to my friend 10 yrs ago “Joe it’s (his Prius) not cost effective”. It’s a Oooo Oooo I’m all electric and as green as I can get. But the electrons for the electric car come’s from coal.

So you have a motor that produces torque starting at low rpm. Doesn't that mean that you need an adjustable pitch prop to take advantage of that torque?
Wasn't there an article in a recent Soundings about an electric charter cat? Sounded really nice until you realized that it had a massive Li-ion battery bank and a big generator that ran most of the time to try and keep up. All very sophisticated which equals expensive.

Having a range of 50mi and a recharge time of 5 days sounds to me like you can drive it 10mi per day forever, or 20mi every other day, etc. 20mi on the water is pretty far around these parts. So, it depends on how far you want to cruise. Many people are content to bob around a little and go home every time.

And for those suggesting one motor, well, since he’s using Prius parts designed to move a 3000lb car, and instead use them to move a 12t boat, I think having two is going to be a lot better than one.

I love the idea, and it’s great to have free fuel from the sun. If you can run a cord to the house then you’re going to get paid to own that boat in no time.

As for rudders, yes you do need them in my opinion. Because of wind, there will be times you want extra authority on the turning radius of the boat. As someone mentioned, without them you will likely be forced to run reverse on one motor more often than you’re thinking, negating any savings on drag. Also, I doubt the drag of rudders is a large portion of the total drag on such a ship. But, I’m no engineer.

Nomad Willy said:

So goes the frontier ...
many say it was the frontier that made America great.
All this electric stuff from batteries is pop energy. It’s hard to say how long it will remain popular but it will melt down eventually. I was up to —- in UL aviation in the 80’s and it definitely was a pop fad. When was the last time you saw an UL? I’m an old man that like old things ... but only certain things. Old furniture from the 50’s .. NO. Cars from the 50’s .. big yes. Ect ect. But I like engines so I almost need to dislike solar and motors. Baugh humbug basically. But like I said to my friend 10 yrs ago “Joe it’s (his Prius) not cost effective”. It’s a Oooo Oooo I’m all electric and as green as I can get. But the electrons for the electric car come’s from coal.

Click to expand...

Are you saying that electric versions of ICE vehicles is a fad? I don’t think so, there will be more and more electrics, less and less ICE, and eventually you will not see any gassers outside the classic car museum.

Following

A local guy built about a 28' boat with a flat top pilothouse/cabin top that was covered about 80% of the boat's footprint with PV panels. Electric motor inboard. He cruised around here for a few years. Definitely was slow, but it did work. I don't think there was a generator on board for when batteries went flat.

Saw the same boat a few years ago, it now has a small outboard four stroke on it.

The solar energy collected is simply too small compared to what is needed to move the boat a reasonable distance. 10nm per day, sure, that is do-able. But that is not very far.

You can augment it with a diesel gennie, but with that running the burn rate per mile is probably on par with a straight shaft propulsion diesel. And then add in the cost for motors, batts, PV panels, controllers and cabling, and you are way upside-down.

With straight diesel propulsion, you can go 10nm for under ten bucks.

Neat technology is available. Lots of cool ways to mix things like motors, PV, batts, gennies, controllers, etc. I love messing with the stuff too. But using rough analysis, the numbers still don't really work except in limited duty cycles.

And do keep the rudders. Yes, they really do add drag. But in any sort of seas you really need them. Trust me on that!!

I think many are missing the point (or maybe I am?). Star-Lord has a project that he WANTS TO DO. He thinks he can make it work but the point is a project he wants to attempt, not what is going to be the most practical propulsion system. His money, his choice.

Maybe TF can offer good suggestions on ways that he can make his idea work, or be less impractical etc.... Suggestions such as “you may want to rethink getting rid fo the rudders” are super helpful. Suggesting that it is just a non-workable silly idea isn’t helpful.