# Crazy Propulsion idea for next cruiser... Thoughts...



## postdoc (Apr 29, 2019)

Hello all, 

I've been dreaming about electric propulsion for my next cruiser. Looking at something like a Jeanneau Sun Odyssey 379 or 389 
(38 foot). My plan is the set this up as my last boat to last me well into and past retirement. I'm sold on the idea of the lower maintenance of the electric drive and the simplicity of a one fuel cruiser. A large bank of lithium cells will allow all the conveniences of an induction range, microwave and possibly even A/C on the odd night at anchor. No need for diesel or propane tanks. 

There are a few offerings for electric sail drive systems on the market and I've gotten the white sheets from most of them.
My initial idea was a 14KW sail drive and a bow thruster for better maneuverability as I'd be in the back row of the tight marina. 

Then I had a thought. Why spend the additional 10K on a bow thruster install? Instead of one sail drive, how about 2 smaller units (7KW) installed port and starboard of center. My thoughts are 1) that smaller drive motors would be better at regenerating at lower speeds than one large unit and 2) while in the marina, two props give you the ability to steer the bow by reversing drive on one prop. Catamaran level steerage skills on a monohull may be possible. 

Any thoughts????


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## TQA (Apr 4, 2009)

Have you done the simplest audit of the daily energy requirements of your boat?

How are you planning to recharge these lithium batteries.

Even if you were to cover every available horizontal space with solar panels you will not get anywhere near enough to run A/C.

I know of a few that have gone the electric power route and they have all fitted generators.


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## Minnesail (Feb 19, 2013)

You would lose the prop wash effect, since your prop would no longer be behind the rudder (unless you have one of those new twin-rudder boats).




This is completely out of my area of expertise, consider me nothing more than a guy at the bar chiming in, but... With twin props if you're counting on regen while under sail wouldn't one of the props be out of the water if you were heeled at all? That would cut your regen in half.


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## Minnewaska (Feb 21, 2010)

Asymmetrical dual prop thrust on a mono hull is still not going to perform like a catamaran or stinkpot. The primary purpose of the keel is to interfere with pushing aside. The bowthruster gets away with it, as it provide thrust exactly perpendicular to the keel and most often at a further leverage distance. 

Aside from your question, the overall design thought may be from the future. I don't think there is such a lithium setup that is going to do all that you want, at least not for very long. Then, you have to recharge it. Hopefully, such options exist at some point. For now, the motivation to get away from diesel maintenance are a valid motivation. Albeit, you won't go very far, without a fuel burning generator. You're not going to get battery powered air conditioning and induction cooking at the same time.


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## capta (Jun 27, 2011)

Up until last month, we had an electric stove/oven. The change has cut our generator time by about 50%.
We have a fairly large solar array and a wind gen, and we couldn't possibly meet our energy needs with both because some days there just isn't enough sun and/or wind to keep up with even half our energy needs. 
As TQA mentioned, your going to need an auxiliary charging system unless you are just day sailing, and plug in every night. Calculate the energy requirements of an electric stove, motive power, and a thruster, not to mention A/C, and you are going to find them astronomical even with a generator. In the end, it's just simple math; can you replenish the energy you consume with any system other than shore power? If not, you are going to get stuck w/o power sooner or later.
If I were to put a thruster on a small sailboat, which I wouldn't do for any reason, I'd go to a hydraulic unit. Electrical systems are the weakest and most susceptible to problems on any vessel. 
As for twin screws on a small sailboat, the props are not going to be far enough apart to give you the control you expect, even with twin rudders.


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## paulinnanaimo (Dec 3, 2016)

If you are starting from scratch, perhaps you could come up with something like the pivoting Volvo drive units. You could swing the stern around like there's no tomorrow.


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## makobuilders (Feb 7, 2014)

*postdoc*, it doesn't hurt to get creative in your thinking, and electric propulsion is wonderful if it suits your usage, but basically you're looking at the following solution as a good proposal:
I assume you're buying a used boat;
Remove and sell off your diesel propulsion engine, replace with a suitable electric motor setup;
Install a generator set powerful enough to quick charge your huge lithium bank and powerful enough to power your electric propulsion motor to at least 50%;
Install induction stove top, not "electric" resistance stovetop;
Mount as much solar as you can without the boat starting to look ridiculous;
Forget about the thruster. Use the money to pay for the genset (in a silent box) and perhaps some boat handling lessons to improve your confidence while docking.


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## mbianka (Sep 19, 2014)

Interesting idea and concept. I've had an EP boat for over ten years now and keep discovering new ways to use it. Things you would never do with a diesel. For example in light winds I crank the motor control a tiny bit to turn the prop just enough to eliminate prop drag. You could do the same with your forward and aft prop idea. Gives you a nice bump up in boat speed and automatically starts regenerating once the wind picks up and no folding mechanical prop issues.

Another idea I've been thinking about. I have a electric outboard for the dingy. I was thinking it would be great to have something like it that would drop down from the bow on a rail for when one needed a bow thruster and pull it up out of the water when under way. I saw something similar being used on a power boat.


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## JimsCAL (May 23, 2007)

Until there is a significant technical breakthrough, all electric boats are going to be limited to daysailing or marina hopping. Just compare the amount battery storage you would need to equal the energy in say 10 gallons of diesel fuel. 

If you are going to have a large diesel generator onboard, I don't see the big advantage over a direct drive diesel for propulsion.


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## Captain Canuck (Oct 20, 2014)

If you're serious about making your boat more maneuverable, you could install an electric pod motor that rotates 360 but locks forward when sailing. I imagine that would be fairly expensive, though.

As far as a general electric conversion goes, you have to be willing to accept both the benefits and limitations the system will impose on you. For my electric conversion, I went with lithium batteries, and saved about 100lbs net after pulling all the diesel components out.

Benefits of electric propulsion include much higher reliability and motor endurance, instant power, regeneration under sail, easy diagnostics and part replacement, universal recharging, and almost no or no maintenance, depending on the motor you choose.

The only real limitation is range, but it's a pretty big limitation. Expect ~1/10th the range of the diesel you replace, assuming you don't have a generator. That being said, a lot of sailors rarely use more than 1/10th of their diesel tank on any given outing. Personally, I'm generally daysailing, so I just need enough to get out of the marina and back in, plus a little more for emergencies.

If you're in a slip on shore power the vast majority of the time, an all electric setup makes sense. If you're making passage and anchoring a lot, you're going to need a both a generator and a very large battery pack to make that kind of system viable. Both electric cooking and electric propulsion take an enormous amount of energy to run. I'm not saying it's impossible, but you'll need much more electric generation than an average boat to make it work.


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## postdoc (Apr 29, 2019)

Thank you all for the feedback. 
I hadn't thought of the resistance that the keel would cause when trying to pivot the bow from the back. A bow thruster is more energy efficient in that regard. And yes, It's always better to have skill over equipment ad equipment fails. A bow thrusters on 38 footers are becoming more common on newer boats as its much cheaper than an emergency hall out and a repair. My wife tends to take the helm and I go forward when docking. I'd like her to have the extra control of the thruster if an emergency arrises. 

I still haven't been able to track down any real number on regenerative capture of energy under sail with different sized motors. Two smaller may still work out better but I'm still looking for the data. 

Our energy needs are manageable even with a 14KW lithium bank. I know some of you worried when I mentioned A/C and induction cooking. Like motoring, they would be done only occasionally. I find that we rarely motor more than 10-15 miles in my current boat. 

Thank you all for the great feedback.


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## Captain Canuck (Oct 20, 2014)

postdoc said:


> I still haven't been able to track down any real number on regenerative capture of energy under sail with different sized motors. Two smaller may still work out better but I'm still looking for the data.


I searched high and low for this kind of data for months and came up with essentially nothing. Lots of speculation, most of it seemingly crazy optimistic or pessimistic. No actual data, though.

I just received my boat-mounted multimeter. This displays Volts, Amps, KW used, current wattage, and a host of other good info. Once I'm back in the water, I'll be able to give you all the data you want on my motor/prop combo. I'm curious myself as to what regen I'll be able to get and at what speed.


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## Cassidy (Apr 13, 2019)

I’m a little old fashioned in my boating so to me electric propulsion on a boat is nothing more than smoke and mirrors. But having said that . . .

I try to sail as much as possible so propulsion would be limited to getting on and off my mooring and in and out of anchorages so the time the electric motor (EM) will run would be minimal. My last ocean crossing, my engine ran for 38 minutes in 7 days. But . . .

Surely if you are dependant on the EM for propulsion and don’t want to run a genset all the time to put back what you use, one would try to steer clear of stuff that uses the same energy source. For example:

- why an electric stove when gas cookers have worked since forever?
- if you’re going to have an EM, hot water for showers etc. needs to be specifically generated so you’ll probably need gas on board anyway (please not another electric appliance, I know the electric heater in our califont murders my electricity reserves). 
- why an electric bow thruster on an essentially smallish boat, many thousands of which have been in service since forever without thrusters?
- why AC when many boats much bigger than 38ft don’t have it? Electrically unaffordable luxury IMO.

If I were to contemplate an EM, I would want as much electrical capacity for propulsion as I could get and would work really hard at eliminating anything else that would compromise that ideal. If you must have one electric device, make it a small watermaker.


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## Jon Bailey (May 16, 2019)

I think of electric motors on yachts just like electric motors in cars. The first ones were average. Wait a year and they get better real quick. Perhaps a selfish approach, albeit one you'd agree with if you're looking at setting your yacht up once and for all for retirement. Perhaps wait a while until the industry and technology catches up with the car industry, and then make the move for electric.


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## Captain Canuck (Oct 20, 2014)

Jon Bailey said:


> I think of electric motors on yachts just like electric motors in cars. The first ones were average. Wait a year and they get better real quick. Perhaps a selfish approach, albeit one you'd agree with if you're looking at setting your yacht up once and for all for retirement. Perhaps wait a while until the industry and technology catches up with the car industry, and then make the move for electric.


Consider that 10 years ago, the electric vehicle market consisted of a single super-expensive roadster made by a half-baked startup that was tripping over it's own feet to get off the ground.

5 years ago, there were about 10 models, with only two having more than 100 miles of range.

Today, there are 40+ models, and the vast majority have 200+ miles of range, some with 300+ miles.

Some car companies have committed to 100% EV or hybrid lines within the next 10 years.

The electric revolution is here. It's only a matter of time before this revolution makes it's way into the marine world.

Electric motors are superior to ICE motors in every measurable way. The only remaining advantage that ICE has is energy density of the fuel (you can go a lot farther on 1lb of diesel than you can on 1lb of even the very best batteries). Once that advantage is reduced, there will be no reason to have an ICE on your boat, other than nostalgia.


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## Minnewaska (Feb 21, 2010)

Captain Canuck said:


> .....The only remaining advantage that ICE has is energy density of the fuel (you can go a lot farther on 1lb of diesel than you can on 1lb of even the very best batteries). Once that advantage is reduced, there will be no reason to have an ICE on your boat, other than nostalgia.


This is exactly correct, in all respects. Unfortunately, that gap has not materially narrowed in decades. Manufacturing costs have come down dramatically, but it is going to take the energy density issue you've identified to really break through. Perhaps it could happen. We'll see. Of course, everything comes with consequences. Imagine the number of dead batteries that will litter the earth, if we don't get ahead of that curve too.


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## Minnesail (Feb 19, 2013)

Are lithium batteries easily recyclable?

I know flooded lead batteries are almost completely recyclable. The nickel metal hydride batteries in my car can be completely recycled.


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## Captain Canuck (Oct 20, 2014)

Minnewaska said:


> This is exactly correct, in all respects. Unfortunately, that gap has not materially narrowed in decades. Manufacturing costs have come down dramatically, but it is going to take the energy density issue you've identified to really break through. Perhaps it could happen. We'll see. Of course, everything comes with consequences. Imagine the number of dead batteries that will litter the earth, if we don't get ahead of that curve too.


Oh, there's a ton of room for improvement on all fronts. However, research on lithium and other novel chemistries has been going gangbusters since the cell phone, and now the electric car revolution started. I've seen at least 6 paths to 10-20x today's best power density being researched by major universities in the past few years.

I wouldn't say there hasn't been a big density breakthrough for decades, unless you're talking lead acid. Lithium batteries get more dense at a surprisingly linear ~7% per year. The big breakthrough has been production efficiencies. Tesla claims to be closing in on $100 per kWh. Considering that cost was $1000 per kWh 8 years ago, that's a pretty massive improvement. $100 is a big number, because at that point the powertrain of an electric car and the powertrain of an ICE car become even, meaning there's no longer a cost advantage to an ICE car. Case in point - the premium for the new generation hybrid Rav4 vs a gas Rav4 is now only $800 - and the hybrid is faster, more powerful, and gets considerably better gas mileage.

As Electric cars become more common, I think we'll continue to see better and better power densities. No idea how long it will take for production and density efficiencies to trickle down to boat world, though. Prices for marine lithium batteries are still in the $1000/kWh range.


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## Minnewaska (Feb 21, 2010)

Captain Canuck said:


> .....I wouldn't say there hasn't been a big density breakthrough for decades, unless you're talking lead acid. Lithium batteries get more dense at a surprisingly linear ~7% per year.......


I think we agree. Lithium is not new technology. It too has been around for decades. Density has been increasing, but the 7% per year you note is going to take a long time to bridge the remaining 2000-3000% density gap. I think it will require an all new technology breakthrough, not just improvement of current battery tech.


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## Captain Canuck (Oct 20, 2014)

Minnewaska said:


> I think we agree. Lithium is not new technology. It too has been around for decades. Density has been increasing, but the 7% per year you note is going to take a long time to bridge the remaining 2000-3000% density gap. I think it will require an all new technology breakthrough, not just improvement of current battery tech.


You're probably right. The current highest density I've read about so far in the Lion realm is 460wh/kg, or roughly double today's average, or about 10x lead-acid density. Graphene based batteries seem to have a lot of promise, too, for both reducing cost and weight.

There are a few other techs farther down the line if they can make it to commercialization. Princeton was working on a carbon nanofiber based tech that, in the lab, far outstripped any other tech yet developed.

Going in the opposite direction, I read about a professor who was working on a battery that fit inside of a container made out of incredibly cheap material, to the tune of about 2MWH per container. The idea was to use them for either powering battery electric trains or using them for grid-based applications where weight and size aren't important, but capacity and reliability is. A big, cheap, reliable battery would go a long way towards finishing off fossil-fuel based power.


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## Minnewaska (Feb 21, 2010)

Captain Canuck said:


> ........A big, cheap, reliable battery would go a long way towards finishing off fossil-fuel based power.


It's just a pet thing for me, when I hear/read the term fossil fuel. We've literally known for 100 years that virtually all crude oil is not from decayed fossils. There simply weren't enough "fossils", compared to what's down there. Somehow that moniker stuck, but it's grossly inaccurate.

In fact, there are scientific theories that methane is actually continuously created deep down inside the earth, which if true, would make it an essentially limitless energy source. That is, for what is likely to be the remaining period of time the earth is inhabitable. Whether humans were here or not, the planet's not always been inhabitable by our life form.

Beyond geopolitical issues, which are significant, the only problem with "carbon" based fuels, is pollution. There is no doubt in my mind that we can invent the technology to nearly eliminate the pollution from carbon based fuels. Natural gas (methane) is naturally (no pun intended) less polluting to begin with and I'm sure we could do even better. However, methane is substantially less energy dense than gasoline or diesel. It likely would need to be converted/concentrated first. The cost of this conversion, along with the cost of extracting deep earth methane, make it economically more expensive than crude. However, so is solar and wind. Although, these so called green energy sources require additional storage technology, such as batteries.

Sorry, "fossil" gets me going.


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## Captain Canuck (Oct 20, 2014)

Minnewaska said:


> It's just a pet thing for me, when I hear/read the term fossil fuel. We've literally known for 100 years that virtually all crude oil is not from decayed fossils. There simply weren't enough "fossils", compared to what's down there. Somehow that moniker stuck, but it's grossly inaccurate.
> 
> In fact, there are scientific theories that methane is actually continuously created deep down inside the earth, which if true, would make it an essentially limitless energy source. That is, for what is likely to be the remaining period of time the earth is inhabitable. Whether humans were here or not, the planet's not always been inhabitable by our life form.
> 
> ...


I can totally relate to requiring accuracy when talking about things. 

The problem with scrubbing carbon from the atmosphere after releasing it is that you have to subtract the energy used in removing it from what you got out of it in the first place. Even with highly efficient scrubbing technology, the net energy gained from carbon based fuels would be less than a non-carbon source, making the carbon based source not economically viable.

Another problem with non-renewable energy is the accidents that occur with their regular use. The absolute worst accidents ever in solar and wind are peanuts compared to a dam collapse, oil spill or nuclear accident.

If the methane idea bears fruit, that would be interesting. But if you're digging a deep hole anyway, why not use it for geothermal instead?

I agree that solar and wind aren't as reliable as, say, a gas fired plant. However, solar, wind and battery, with enough capacity, would easily replace carbon based fuels. The trick is to get a big, cheap battery pack to attach to solar and wind farms to keep the electricity flowing on off days.

According to the Energy Information Administration, wind edged out combined gas as the cheapest source of electricity in 2018. The three cheapest are now Wind, Combined Gas, and Solar PV, in that order. Nuclear is the both the most expensive and has the longest plant assembly time and startup costs (10+ years and $25B+ per reactor).

I hope I see hydrogen fusion become practical in my lifetime. Unlimited cheap power would open up a lot of possibilities.


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## Minnewaska (Feb 21, 2010)

Captain Canuck said:


> ...The problem with scrubbing carbon from the atmosphere after releasing it


Perhaps the technology will be to capture it, rather than release it, or to alter it, such that's it doesn't have the same pollution affect.



> Even with highly efficient scrubbing technology, the net energy gained from carbon based fuels would be less than a non-carbon source, making the carbon based source not economically viable.


That may be true, based on today's technology. All these challenges are often overcome in time. Commercial viability is key.



> Another problem with non-renewable energy is the accidents that occur with their regular use. The absolute worst accidents ever in solar and wind are peanuts compared to a dam collapse, oil spill or nuclear accident.


A dam collapse? Isn't that a renewable green energy source? Albeit one with flooding consequences.



> If the methane idea bears fruit, that would be interesting. But if you're digging a deep hole anyway, why not use it for geothermal instead?


Geothermal is not as energy dense, just the point we're discussing. It's also not portable, like carbon fuel.



> I agree that solar and wind aren't as reliable as, say, a gas fired plant. However, solar, wind and battery, with enough capacity, would easily replace carbon based fuels. The trick is to get a big, cheap battery pack to attach to solar and wind farms to keep the electricity flowing on off days.


That is the trick. I'm not reading any scientific expectation that we'll develop that volume of batteries to replace the energy grid and transportation. The batteries all consume significant natural resources as well. What I'm reading about are ideas like pumping water into basins, during sunlight, so they can drain and run turbines in the dark. Not sure we've got the grid replacement figured out yet.



> According to the Energy Information Administration, wind edged out combined gas as the cheapest source of electricity in 2018. The three cheapest are now Wind, Combined Gas, and Solar PV, in that order. Nuclear is the both the most expensive and has the longest plant assembly time and startup costs (10+ years and $25B+ per reactor).


I'll have to research this. It would seem nuclear construction costs amortize over time and I wonder whether the costs of each of these examples are gross or net of government subsidy. When it comes to real cost, society needs to examine gross. The government subsidies are being paid for by the same consumers, in a different bill.



> I hope I see hydrogen fusion become practical in my lifetime. Unlimited cheap power would open up a lot of possibilities.


Maybe.


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## Jeff_H (Feb 26, 2000)

I often hear people citing concerns about the unreliability of wind and solar power and the issue of being able to store energy to balance the peaks and lulls in usage and production. One of the first answers that seems to get floated is the idea of very large battery banks storing energy during peak production periods to be used when production is less than usage. From everything that I have read, the ability to do that cheaply and efficiently is a long way off and frankly in many (most) large scale applications may never be viable.

But, since the late 1960's there have been a number of very large, efficient, and relatively inexpensive to build and operate energy storage facilities around the country and the world. In operation these are essentially carbon neutral (although there is certainly embodied energy in building one). These systems are typically referred to as some variation of "Pumped water energy storage facilities". There are literally dozens of them in the US at this point, but the largest two are in these links below:

https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant
https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station
https://www.dominionenergy.com/comp...tion/water/bath-county-pumped-storage-station

Obviously these are not portable power in the same way that carbon based engines, fuel cells, solar panels, and wind/water driven generators are, but they do allow balanced energy sourcing that has a greatly diminished dependency on carbon based power sources from renewable sources that can be accomplished with a readily available technology source.

Jeff


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## TQA (Apr 4, 2009)

Captain Canuck said:


> You're probably right. The current highest density I've read about so far in the Lion realm is 460wh/kg, or roughly double today's average, or about 10x lead-acid density. Graphene based batteries seem to have a lot of promise, too, for both reducing cost and weight.
> 
> There are a few other techs farther down the line if they can make it to commercialization. Princeton was working on a carbon nanofiber based tech that, in the lab, far outstripped any other tech yet developed.
> 
> Going in the opposite direction, I read about a professor who was working on a battery that fit inside of a container made out of incredibly cheap material, to the tune of about 2MWH per container. The idea was to use them for either powering battery electric trains or using them for grid-based applications where weight and size aren't important, but capacity and reliability is. * A big, cheap, reliable battery would go a long way towards finishing off fossil-fuel based power*.


People forget that you still have to generate this electrical energy.

Are you going to cover your boat with solar panels.

On land nuclear is the ONLY realistic alternative for large scale 24/7 energy generation. If we switch off every dead dinosaur engine we are going to need a s*** load of alternative energy if we want to drive around with the AC on and have AC in summer and heat in winter in our homes.


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## Cassidy (Apr 13, 2019)

Perhaps if the electric powered vessel remains coastal/local then comparing battery capacity of a car with fuel (diesel/petrol) capacity of a similar car works. But when you’re talking boats that go further afield that comparison loses validity. Why? Well simply because few cars have 400 litre fuel tanks.

I reckon it’ll take a while before a practically usable battery bank that will work on a boat can match the energy density of that much fuel.

Disclaimer: I just heard the term “energy density” a few minutes ago for the first time 🙂. Perhaps my opinion above needs adjustment.


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## Minnewaska (Feb 21, 2010)

The only subtle difference on a cruising sailboat is it can “refuel” it’s batteries via solar, wind or hydro. However, the point stands. That technology isn’t efficient enough to reliably replace the amount of time/distance one can get out of a tank of diesel. At least not yet.


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## Minnesail (Feb 19, 2013)

Minnewaska said:


> In fact, there are scientific theories that methane is actually continuously created deep down inside the earth, which if true, would make it an essentially limitless energy source.


This is known as abiogenic petroleum theory, and it is *very* fringe.

My dad is a geologist. It wasn't a big deal when I quit going to church, but if I had started believing in abiogenic petroleum he probably would have kicked me out of the house!

Fossil fuels are so named because the first scientists who studied them noticed the fuels are found in the same strata with fossils and thought the fuels came from the fossils. When I was a kid I went to a lot of job sites with my dad and coal work was great because coal beds are awesome for fossil hunting. In fact some lignite coal *is* fossil wood and still even looks like wood. It's crazy.


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## Minnewaska (Feb 21, 2010)

Minnesail said:


> This is known as abiogenic petroleum theory, and it is *very* fringe.
> 
> My dad is a geologist. It wasn't a big deal when I quit going to church, but if I had started believing in abiogenic petroleum he probably would have kicked me out of the house!.....


Some of the greatest discoveries of all time were received this way, until proven correct. I'm not placing bets, but it only encourages me to hear mainstream rejection.  I understand the Russians continue to pursue the idea to this day.


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## Captain Canuck (Oct 20, 2014)

Cassidy said:


> Perhaps if the electric powered vessel remains coastal/local then comparing battery capacity of a car with fuel (diesel/petrol) capacity of a similar car works. But when you're talking boats that go further afield that comparison loses validity. Why? Well simply because few cars have 400 litre fuel tanks.
> 
> I reckon it'll take a while before a practically usable battery bank that will work on a boat can match the energy density of that much fuel.
> 
> Disclaimer: I just heard the term "energy density" a few minutes ago for the first time ?. Perhaps my opinion above needs adjustment.


Ah, but a car has no way to generate energy while in motion. A gas tank is just a type of battery - once it's gone, it's gone until you find a place to refuel. Sailboats, on the other hand, have several ways to draw fuel in from the outside. An all electric boat can generate fuel via wind, solar, or propeller drag while under sail. Hell, you could even put a bicycle generator on there, if you think the roughly 1/4 horsepower your legs can generate is worth it. That's about a kWh every 3 hours of pedaling. Good exercise, though. 

Power boats are a whole other story. They are generally *ridiculously* inefficient, with very few exceptions. It will be a long time before electric power becomes practical in that realm. Only little super-efficient (read:slow) trawlers like the Albin could even consider a conversion at this point.

Power density is energy per unit of weight, generally expressed in WH/kg. Diesel's energy density is 11.6 kwh/kg. Modern lithium batteries are around .25 kwh/kg. Lead acids are around .05 kwh/kg. These numbers are a little misleading, as electric motors are more than twice as efficient at converting energy into work than a diesel is. If you normalize the numbers, it's closer to 5kwh/kg useable for diesel. Even so, that's a 20-fold advantage for diesel over current lithium.

Batteries have a long way to go to catch up to diesel.


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## Captain Canuck (Oct 20, 2014)

TQA said:


> People forget that you still have to generate this electrical energy.
> 
> Are you going to cover your boat with solar panels.
> 
> On land nuclear is the ONLY realistic alternative for large scale 24/7 energy generation. If we switch off every dead dinosaur engine we are going to need a s*** load of alternative energy if we want to drive around with the AC on and have AC in summer and heat in winter in our homes.


If by realistic you mean horribly expensive with incredibly long build times, then yes, you're right. Building a nuclear power plant is a massive expenditure of time and money, and it's always financed by the public. Sometimes they don't even get fully built due to insane cost overruns. The VC Summer reactors are case in point: the projected cost was $5.1 billion. $9 billion later, they're still not finished and 5 years behind schedule, with a revised cost of $25B. The project was abandoned.

MW per MW, you can build solar farm capacity 5-6x faster than you can build nuclear capacity. Plus, solar PV is upgradable - if better panels come along, you can swap them into the existing infrastructure, provided you've built in enough excess carrying capacity.

I agree that we're going to need something, probably gigantic batteries, to level out the current for when there are cloudy and less windy days. Since it takes, at minimum, 10 years to build a nuclear power plant, I'm certain that in that time a better solution will come along.


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## JimsCAL (May 23, 2007)

Captain Canuck said:


> I agree that we're going to need something, probably gigantic batteries, to level out the current for when there are cloudy and less windy days. Since it takes, at minimum, 10 years to build a nuclear power plant, I'm certain that in that time a better solution will come along.


You obviously have been drinking the renewable energy KoolAid. Wind and solar are great additions to the electric energy production arsenal. But the intermittent nature of the production is a HUGE disadvantage. I don't think you have a clue as to how big the energy storage issue is. Maybe a reasonable solution will come along in a few decades, but I think even that may be optimistic. Until then, natural gas is going to remain the logical solution for base load power.


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## Minnesail (Feb 19, 2013)

Natural gas is great because it can be ramped up and down quickly to respond to need, whereas nuclear and coal are more fixed. Hydropower can also be ramped up and down quickly.

However solar and wind aren't as intermittent as you might think, because the electrical grid can smooth out shortages in one area by bringing in electricity from another. Advances in grid technology will open up other options for regulating power, like demand pricing. 

I work at a manufacturing plant that uses a fair amount of electricity and right now we have a fairly crude system of demand pricing: if it's going to be a high demand day they call us and ask us to shut down a certain amount of load. We can opt to go over that, but we pay a significant fee.

I can imagine systems where you'd plug your car or boat in, but set it so that it won't start charging until the price of electricity drops below a certain threshold (which would probably be sometime in the middle of the night). High electric consumers like aluminum manufacturing would vary production based on price.


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## danvon (Dec 10, 2012)

Minnesail said:


> Natural gas is great because it can be ramped up and down quickly to respond to need, whereas nuclear and coal are more fixed. Hydropower can also be ramped up and down quickly.
> 
> However solar and wind aren't as intermittent as you might think, because the electrical grid can smooth out shortages in one area by bringing in electricity from another. Advances in grid technology will open up other options for regulating power, like demand pricing.
> 
> I can imagine systems where you'd plug your car or boat in, but set it so that it won't start charging until the price of electricity drops below a certain threshold (which would probably be sometime in the middle of the night). High electric consumers like aluminum manufacturing would vary production based on price.


Exactly. Not only does production tend to balance out over larger regions but demand does too (i.e., California uses a ton of power for AC in summer, when power demands are relatively low in the PNW - summer is when we generate a lot of solar in the NW and don't need all of it. similarly CA is still producing solar power in winter when we need it for heating and they don't so much). We just need a good grid to move it round.

Also, charging your car at low-demand times is doable (and done) now. That makes a ton of sense where the base power production is on all the time but not heavily used at night.

As others have noted, the range issue has largely been solved for EVs. A 300 mile range is more than enough for almost anyone so long as rapid charge stations are available along highway for long road trips, and they are being installed fast (especially if you own a vehicle made by the "half-baked startup" that someone mentioned, which is building its own network). We have a Leaf with a 107 mile range and even that is enough for almost everything we do in the urban area.

But the difference between cars and boats, and the real problem for electric boats, is that by the nature of a car you are almost always going to be somewhere you can recharge on a daily basis. Not so much the sailboat. It's hard to imagine using one for anything but short trips without some way to recharge, like a genset. That in itself is not horrible - you would in effect be operating like a plug-in hybrid car, which saves a ton of fuel. I know someone with a plug-in Prius who gets gas every 2-3 months.


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## TQA (Apr 4, 2009)

IMHO the really scary thing about nuclear power is the time it takes to build a power station. Sure the current time is around 10 years that is 6 months to a year of work and 9 years futzing around with politics and health and safety.

But if the lights start going out and people are facing rolling power cuts and industry has to shut down I bet there will be some fast tracking and the risks will go up, way up especially as there will be less training time.

BTW The French have 68 working nuclear power stations.


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## Cassidy (Apr 13, 2019)

Captain Canuck said:


> An all electric boat can generate fuel via wind, solar, or propeller drag while under sail.


Actually my boat can also do the first two of those and that's why I know how hopelessly inefficient it would be to replace diesel. 

My watermaker has a 1.5hp electric motor and the only way I can run that for an hour or more is to run the diesel at the same time. The current draw from my house bank is about 160A when it's running at 850psi.

And that's a baby electric motor compared to a primary drive motor.


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## mbianka (Sep 19, 2014)

Cassidy said:


> Actually my boat can also do the first two of those and that's why I know how hopelessly inefficient it would be to replace diesel.


But that's only generating fuel (energy) for your electric system not fuel for propulsion as in an EP system. With an EP system you are generating energy for both using solar and wind and also underway with regen. They continue making energy while at anchor and the EP battery bank can be tapped as needed for heavy use too. Or a small generator can be had as a back up when needed.


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## Cassidy (Apr 13, 2019)

mbianka said:


> But that's only generating fuel (energy) for your electric system not fuel for propulsion as in an EP system. With an EP system you are generating energy for both using solar and wind and also underway with regen. They continue making energy while at anchor and the EP battery bank can be tapped as needed for heavy use too. Or a small generator can be had as a back up when needed.


I must confess to not having done any research into a subject in which my interest is very peripheral but I suspect that an EP requires a lot more that 1.5hp. Maybe 10 times as much? More?

What evidence suggests that my passives, which can't keep up with a 1.5hp electric motor are going to keep up with a vastly bigger electric motor irrespective of battery chemistry. Unless there has been some incredible advances in battery and electric motor technology that I've missed, power draw is power draw.

Also, regeneration off the propshaft is not really fireworks, probably not more than a decent solar array and generates nix when anchored.

Maybe I shouldn't make assumptions I know nothing about.


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## mbianka (Sep 19, 2014)

Cassidy said:


> I must confess to not having done any research into a subject in which my interest is very peripheral but I suspect that an EP requires a lot more that 1.5hp. Maybe 10 times as much? More?
> 
> What evidence suggests that my passives, which can't keep up with a 1.5hp electric motor are going to keep up with a vastly bigger electric motor irrespective of battery chemistry. Unless there has been some incredible advances in battery and electric motor technology that I've missed, power draw is power draw.
> 
> ...


No problems EP can be counter intuitive. Though it is useful in many more ways on board than diesel as I have found out over the years. When I converted to EP back in 2008 it was more a leap of faith since there were not any boats that were comparable to mine that I could find that had converted to Electric Propulsion. Doing my annual harbor tests: https://biankablog.blogspot.com/2015/07/harbor-test-2015.html 
I discovered the sweet spot for the hull is three to four knots using around 900 watts of power. While at around 2.5 knots I only need about 480 watts. My next goal for my system is adding enough solar to operate entirely on solar at that speed. I already have 120 watts on board so I'm keeping an eye on solar panel tech improvements. In the meantime I am totally happy with my EP system as is. But, the beauty of EP is it is easy to upgrade as the technology improves.


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## Minnewaska (Feb 21, 2010)

mbianka said:


> .....While at around 2.5 knots I only need about 480 watts. My next goal for my system is adding enough solar to operate entirely on solar at that speed. I already have 120 watts on board so I'm keeping an eye on solar panel tech improvements....


You're a frontiersman for sure and I'm glad you like your EP. Just to understand, you're hoping to add enough solar to make 2.5kts, without need to recharge? If so, this essentially makes the point about it being a tough cruisers choice. That speed would be a dead stop in the face of some conditions. As I'm sure you know, in order to get a continuous reliable 480 watts of solar PV production, you'll need substantially more capability. Of course, it will do no good at night or in a storm.

I'm not arguing against your path, just pointing out the shortcomings for long distance cruising. The hybrid approach, I know you also employ, does make it a bit more feasible, but the OP was about a "one fuel" cruising system. Curious what solar tech improvements you're waiting for. I see it getting less expensive, but I'm not reading about any imminent significant efficiency per PV sqft or other such improvements.


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## Captain Canuck (Oct 20, 2014)

Cassidy said:


> Actually my boat can also do the first two of those and that's why I know how hopelessly inefficient it would be to replace diesel.
> 
> My watermaker has a 1.5hp electric motor and the only way I can run that for an hour or more is to run the diesel at the same time. The current draw from my house bank is about 160A when it's running at 850psi.
> 
> And that's a baby electric motor compared to a primary drive motor.


Your house bank is also probably a) tiny relative to a propulsion bank and b) lead-acid. Because of Peukert, the bigger the draw the less power you get.

The house bank on my boat prior to conversion was a pair of 105AH (20hr rate) AGMs. That's 210 AH @ 12V or 2.5KWH at the absolute slowest rate of discharge. You want to discharge to less than 50% to make the batteries last, though, so now you're down to 1.25KWH of usable capacity. To add insult to injury, the lead-acid charging rate is limited, so if you do dip down to 50%, it's going to take hours to get back up to 100%.

In comparison, my lithium drive bank is just over 9KWH with a cutoff of 20% SOC, or roughly 6x my usable house bank. They're much more energy dense, don't have differentiated charge curves, absorb charge at a rate that would fry a lead acid battery, and have at least 10x the cycle life. As long as I take care of the batteries, I doubt I'll ever wear them out. Assuming it takes a full cycle to get out of the marina and back again, that's 5.4 years of going out every single day.


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## Captain Canuck (Oct 20, 2014)

TQA said:


> IMHO the really scary thing about nuclear power is the time it takes to build a power station. Sure the current time is around 10 years that is 6 months to a year of work and 9 years futzing around with politics and health and safety.
> 
> But if the lights start going out and people are facing rolling power cuts and industry has to shut down I bet there will be some fast tracking and the risks will go up, way up especially as there will be less training time.
> 
> BTW The French have 68 working nuclear power stations.


It takes a lot more than 6 months just for the construction. But like any project, it's subject to staged inspections, and that does add time. Well worth it, considering the consequences of a catastrophic failure.

There are plenty of ways to mitigate demand other than building new plants. Here in MD the utilities do things like offer rebates for buying high efficiency appliances, educate people on why they should dump incandescent bulbs, offering incentives to charge electric cars at night, etc.

France has a mostly-nuclear grid for a very good reason. After the oil shock of 1973 (France as mostly oil-based electric at the time), they decided to make themselves fossil fuel independent, and went mostly nuclear. As of about 2008, they've started replacing their nuclear with renewables, with the goal to drop to 50% nuclear by 2035. They also export electricity to the tune of about 3B Euro a year, so there's a big financial incentive to keep electricity cheap enough to export. Hence they were a bit late to the game with solar and wind. They don't have the same pollution issues most other countries have.


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## mbianka (Sep 19, 2014)

Minnewaska said:


> You're a frontiersman for sure and I'm glad you like your EP. Just to understand, you're hoping to add enough solar to make 2.5kts, without need to recharge? If so, this essentially makes the point about it being a tough cruisers choice. That speed would be a dead stop in the face of some conditions. As I'm sure you know, in order to get a continuous reliable 480 watts of solar PV production, you'll need substantially more capability. Of course, it will do no good at night or in a storm.
> 
> I'm not arguing against your path, just pointing out the shortcomings for long distance cruising. The hybrid approach, I know you also employ, does make it a bit more feasible, but the OP was about a "one fuel" cruising system. Curious what solar tech improvements you're waiting for. I see it getting less expensive, but I'm not reading about any imminent significant efficiency per PV sqft or other such improvements.


I certainly understand the hesitation about EP conversions for some. I certainly had to make a leap of faith when I did the conversion in 2008. But, having had over ten years experience there is no place I would not take my boat now that I did with my diesel. Indeed I feel it is a much better experience than when I had the diesel. It is MUCH quieter and much less vibration when doing extended motoring. Even when Electro Sailing with the generator running. Which does not happen that often. As for long distance cruising I'm sure you know their are people cruising with no engine at all. Kevin Boothbay comes to mind.

As for aiming for a pure solar operation at 2.5 knots. It is just a goal to aim for and shows how one can take advantage of new technologies as they come along. Once you install a diesel, well there you are. EP is adaptable. While 2.5 knots may not seem like much under solar. if you were stuck in the doldrums it's better than flopping around and worrying about the limited amount of diesel you still have on board. Don't forget you still have additional power from the battery bank or generator you can draw on as needed. For example at night.

With EP I have a multi-legged stool for making fuel (energy). This includes solar, wind, prop regen and a small generator as needed for charging and Electro sailing. In fact I'm adding a new generator into the mix this season. It will provide more power than my current Honda 2000 for faster charging and Electro Sailing. It's bigger than that workhorse Honda but, has other features like electric and remote start. It's another example of EP upgrade adaptability and also gives me another backup for charging at minimal cost.

If the original OP is planning on doing day trips in and out of a marina dock then a pure EP system would work fine. For my cruising needs I wanted to make sure I had the range when I needed it and the ability to charge batteries fast without going to land. Though it is primarily a sailboat and that's how I like to use it. But, I never hesitate to add a little EP power when needed. Unlike when I was loath to fire up the diesel when the winds started to lighten. EP compliments the sailing experience beautifully. Personally I really don't see any limitations for long distance cruising with an EP system like mine.


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## Cassidy (Apr 13, 2019)

Minnewaska said:


> If so, this essentially makes the point about it being a tough cruisers choice. That speed would be a dead stop in the face of some conditions.


Geez, why did I find it so tough to say this?


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## Cassidy (Apr 13, 2019)

Captain Canuck said:


> Your house bank is also probably a) tiny relative to a propulsion bank and b) lead-acid.


My house bank is 700AH so not that tiny at 8.4kw but yes, it is lead acid.

I stand in awe of your battery bank but no matter how fast your bank can absorb charge and all those other good things, the current solar capability is somewhat limited especially on cloudy days, so is wind and water generation and the power that your bank so gleefully gives up to the propulsion cause has to be put back from somewhere. Genset or shorepower yes, passive sources maybe not.

Reading the last sentence of your post re getting in and out of the Marina taking one full cycle, what do you do if you're 10 miles from home and a strong headwind develops and the bad weather looks like deepening and nightfall approaches?

Look I'm sure it works for you and probably many others - my opinion is it's not for me.


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## paulinnanaimo (Dec 3, 2016)

So bad weather is approaching. It's a headwind. It's getting dark. What's a sailor to do? Why turn on the motor of course.


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## JimsCAL (May 23, 2007)

TQA said:


> BTW The French have 68 working nuclear power stations.


And they are breeders with fuel recycling which the US started, but walked away from in the 1970s due to political pressures. Even with no new nucs having come on line in decades and all the wind and solar farms that have been put in in recent years, nucs still generate over twice the kWhrs of solar and wind combined. And natural gas and coal produce close to 10 times that of solar and nuclear combined.

So most of the power used by those Tesla autos is coming from burning hydrocarbon fuels, just someplace other than under the hood.


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## Minnewaska (Feb 21, 2010)

mbianka said:


> ......As for long distance cruising I'm sure you know their are people cruising with no engine at all. Kevin Boothbay comes to mind.


I'm not trying to talk anyone out of EP. If an engineless boat is the comparison, I won't argue that EP, even at 2.5kts, isn't a vast improvement. EP is also quieter, cleaner and has less maintenance. No beef there.

However, if one wants the utility to make hull speed in the doldrums, or needs to run out of the way of a storm for 48 hrs, EP with only renewables just won't get the job done. This is done with diesel, without breaking a sweat. Add a fuel burning generator to EP and that changes the calculus. One now has two motors, instead of one, and redundancy is always pretty good. Although, one is right back to why carbon fuel has an energy density and portability advantage.

EP and solar/wind regen only, won't get one cruising too far. Unless, ironically, the engineless comparison is made.

I think we'll see EP on more boats in the near future, because most boats do not go very far and having a small generator as a safety net will get the job done. I don't see it for serious blue water boats anytime soon. Unless, again, one would be willing to make those trips engineless. Ironically, I'd say more than half the sailors I know, typically stay pretty close and could get away with EP, but outfit and keep their boat in the condition needed for an offshore cruise they may make once a year. Has something to do with the bug, I guess.


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## Captain Canuck (Oct 20, 2014)

Cassidy said:


> My house bank is 700AH so not that tiny at 8.4kw but yes, it is lead acid.
> 
> I stand in awe of your battery bank but no matter how fast your bank can absorb charge and all those other good things, the current solar capability is somewhat limited especially on cloudy days, so is wind and water generation and the power that your bank so gleefully gives up to the propulsion cause has to be put back from somewhere. Genset or shorepower yes, passive sources maybe not.
> 
> ...


That's a pretty massive, as house banks go. That must be around 600lbs of lead acid.

One of the big question marks for my build is regeneration. I won't have any hard data on that until she's back in the water and I can do some testing. I'll be posting all of that once I have it. How much regen I get is going to go a long way towards determining a doable power budget for longer trips. This will also go a long way towards me estimating the power budget for an eventual catamaran conversion.

I would never be in the situation as you stated it. However, if I was that far from the marina, I'd probably have a full propulsion bank, so 10 miles even into a headwind should be no problem. I it was, I'd just powersail as close to the wind as I could and tack. Failing that, there are plenty of sheltered areas ~10 miles from my marina where I could drop anchor. This is the Chesapeake bay we're talking about, not the open ocean. Khaleesea is a coastal boat or bay cruiser, not a blue water boat, even with a diesel.


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## Captain Canuck (Oct 20, 2014)

JimsCAL said:


> So most of the power used by those Tesla autos is coming from burning hydrocarbon fuels, just someplace other than under the hood.


While cars do run at least partially on carbon based fuels burned at power plants, how much it pollutes depends greatly on where you live. But don't think for a moment that they are somehow "just as bad" as gas powered cars. In most states, EVs are *considerably* greener than any gas powered car, even the latest hybrids.

Kentucky and WV have the most carbon-based electricity production. Even then, an average EV gets the equivalent of a 45 MPG car, meaning it's better than anything short of a Prius.

In MD, where I live, it's the equivalent of a 70 MPG car.

In the best state, WA, it's the equivalent of an 85 MPG car.

In Quebec, which is 99% renewables, it's effectively carbon-free. It's also the cheapest electricity in North America at 7.7c/kwh.

Then there's the cost of electricity vs gas. In no state is it cheaper to run a car on gas than electricity. Even in HI, where electricity is the most expensive, it's still cheaper to run on electricity. Going the other way, in ND, where electricity is the cheapest in the country, it's ~1/3 the cost of gas per mile.


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## mbianka (Sep 19, 2014)

Minnewaska said:


> I'm not trying to talk anyone out of EP. If an engineless boat is the comparison, I won't argue that EP, even at 2.5kts, isn't a vast improvement. EP is also quieter, cleaner and has less maintenance. No beef there.
> 
> However, if one wants the utility to make hull speed in the doldrums, or needs to run out of the way of a storm for 48 hrs, EP with only renewables just won't get the job done. This is done with diesel, without breaking a sweat. Add a fuel burning generator to EP and that changes the calculus. One now has two motors, instead of one, and redundancy is always pretty good. Although, one is right back to why carbon fuel has an energy density and portability advantage.
> 
> ...


Remember that 2.5 knots would be totally fuel free. I agree if you had a diesel you would go faster but, you are burning through your limited fuel reserves on a long passage. Using solar would give you more range and preserve your fuel reserves.

I agree also we will start seeing more and more EP boats. I've see a number converted since I did my conversion and often get questions about it. I think this fellow who converted a 58 foot Voyager catamaran pretty much sums up the benefits and trade offs of Electric Propulsion:


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## Minnewaska (Feb 21, 2010)

Captain Canuck said:


> ...In Quebec, which is 99% renewables, it's effectively carbon-free. It's also the cheapest electricity in North America at 7.7c/kwh..


I'm fascinated by this. First thought is whether this is driven by hydro electric production and how that relates to or is impacted by current Great Lakes flooding. Second thought is whether this is the net cost to the consumer and whether there is any government manipulation, such as production subsidies or tax exemption and it's not apples to apples. I really don't know either, but it's curious how one place could figure out how renewables actually cost less (all in) than carbon, at the moment.


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## Captain Canuck (Oct 20, 2014)

Minnewaska said:


> I'm fascinated by this. First thought is whether this is driven by hydro electric production and how that relates to or is impacted by current Great Lakes flooding. Second thought is whether this is the net cost to the consumer and whether there is any government manipulation, such as production subsidies or tax exemption and it's not apples to apples. I really don't know either, but it's curious how one place could figure out how renewables actually cost less (all in) than carbon, at the moment.


I lived in Quebec for 2 years before moving to the US. My electricity cost was 5.5c/kwh at the time. (1993-4) I'm fairly certain that electricity isn't subsidized - but production is a state owned entity, which keeps costs down as there's no profit motive. Quebec also sells excess electricity to the US, which I'm sure is sold at a fair profit. Even at 10c/kwh that's a lot cheaper than NY's going rate.

Quebec is 95% hydro power, 4% wind power, and 1% other. If you look at geography, Quebec has a big percentage of mountains and rivers - perfect for hydro and wind. This isn't a recent development - it's always been cheaper for Quebec to build another dam than to build, say, a nuclear plant.

Quebec also went big - the James Bay project, built in the early eighties, has a combined output of ~16GW. It was the largest complex in the world at the time, and built in a very harsh climate.


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## Minnewaska (Feb 21, 2010)

95% hydro is clearly the big answer. Not available everywhere. There is an interrelated dynamic downstream with these dams that I don't fully understand. I suspect they are more impactful than we realize. 

When an entity is government owned, it does not take away the profit motive. It only allows them to compete, without paying taxes, which does reduce cost. By extension, everything could be cheaper, without taxes. If these government entities don't profit, they can't afford to rebuild infrastructure, add new dams, etc. Unless, of course, the government provides that with other tax payer funds, it which case, that isn't the all in cost of producing juice.


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## Captain Canuck (Oct 20, 2014)

Minnewaska said:


> 95% hydro is clearly the big answer. Not available everywhere. There is an interrelated dynamic downstream with these dams that I don't fully understand. I suspect they are more impactful than we realize.
> 
> When an entity is government owned, it does not take away the profit motive. It only allows them to compete, without paying taxes, which does reduce cost. By extension, everything could be cheaper, without taxes. If these government entities don't profit, they can't afford to rebuild infrastructure, add new dams, etc. Unless, of course, the government provides that with other tax payer funds, it which case, that isn't the all in cost of producing juice.


Geography definitely plays a big part of why Quebec generates electricity the way it does. Canada as a whole is 60% hydro power. Again, geography.

Quebec Hydro is a state run monopoly. There's literally no one to compete against. It's run as a chartered crown corporation, which means that any time it wants to do something big, a group of lawyers looks at the charter and if it's within the charter's parameters, it goes to the legislature for a decision. This includes things like rate hikes, building projects, etc. The legislature consults with experts and makes a decision. More than once proposals have been shot down as an unnecessary expense. This includes things like CEO raises, bonuses, etc. Consider that the CEO of Quebec Hydro made about $800k last year, including bonuses. Contrast that with the CEO of Pepco making $15.4 million and you can begin to see the advantages of state run utilities. It's hard to get greedy when every major financial decision has to be run by the provincial legislature.

As an aside, there's no money in Canadian politics - everyone runs on state money, the elections are short, and everyone gets the same amount. Without mountains of dark money to influence elections, the politicians are beholden to the people who elected them, not the people who financed them.


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## mbianka (Sep 19, 2014)

Came across another boat with Electric Propulsion making a long passage. Fellow sailed from Los Angeles to Hawaii on a 23 foot boat:


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## Captain Canuck (Oct 20, 2014)

I have some numbers to share.

I had Khaleesea out in nice, strong wind and was able to get her up to hull speed (thank you, Chesapeake summer doldrums, for giving me a break).

At 7 kts, I was getting ~15 amps of regen at 48V. That's 60A at 12V or 1440 amp-hours a day.

While I acknowledge that Khaleesea probably couldn't maintain that speed all day (at least not comfortably) I'm told that 7kts constant is pretty reasonable in most 40'-ish catamarans while making passage. With dual EP drive, that's a daily power budget of a whopping 2880 amp-hours a day, and that's assuming it's a dual motor setup like mine, which would probably be under-powering the boat by a fair margin. Larger motors and props could generate quite a bit more.

It could turn out that a dual-EP catamaran has the opposite problem most boats have - it generates too much electricity when under sail. You could counter that by running the motors for a couple of hours a day to give you an extra knot or two for a few hours each day.

You'd still need solar and/or wind for when you were at anchor, of course.


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## mbianka (Sep 19, 2014)

Captain Canuck said:


> It could turn out that a dual-EP catamaran has the opposite problem most boats have - it generates too much electricity when under sail. You could counter that by running the motors for a couple of hours a day to give you an extra knot or two for a few hours each day.
> 
> You'd still need solar and/or wind for when you were at anchor, of course.


That was the problem the first electric Lagoon delivery crew had when crossing the Atlantic. They had to run the air conditioning to keep enough load on so as to not overcharge the batteries.


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## Captain Canuck (Oct 20, 2014)

mbianka said:


> That was the problem the first electric Lagoon delivery crew had when crossing the Atlantic. They had to run the air conditioning to keep enough load on so as to not overcharge the batteries.


I'm not surprised. Must have been a nice bonus for the crew to be able to make a crossing in air conditioning.

Top Secret is a really interesting boat. Superb wiring job from what I saw. The captain made some interesting points. Separating each solar panel with it's own controller and then feeding a step-up converter for the propulsion bank would indeed be much more expensive (and more efficient) than wiring a bunch serially.

24 kWh and 48V motors seems too small for a boat that size, but that seems to be a regulatory issue more than a practical one. I imagine it takes quite a few amps at 48v to push a boat that big.


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## mbianka (Sep 19, 2014)

Captain Canuck said:


> I'm not surprised. Must have been a nice bonus for the crew to be able to make a crossing in air conditioning.
> 
> Top Secret is a really interesting boat. Superb wiring job from what I saw. The captain made some interesting points. Separating each solar panel with it's own controller and then feeding a step-up converter for the propulsion bank would indeed be much more expensive (and more efficient) than wiring a bunch serially.
> 
> 24 kWh and 48V motors seems too small for a boat that size, but that seems to be a regulatory issue more than a practical one. I imagine it takes quite a few amps at 48v to push a boat that big.


I'd like to experiment with some cheap 12 volt solar controllers to charge each AGM battery individually. That's how my 120 volt Dual Pro Charger works.

Many people have also gotten away from the concept of the engine/motor as auxiliary propulsion on a sailboat. My experience is that unlike a diesel engine. Electric propulsion complements the sails very nicely without the noise, vibration and heat of a combustion engine. With the addition benefit of recharging the batteries while underway and with solar at anchor. Plus it is easily upgraded. I'm in the process of testing additional amps for when I do electro sail. Got a new generator with remote start and an additional power supply to deliver more amps preserving the capacity of the battery bank. But primarily I use the boat as a sailboat and use the EP portion only as needed.


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## Captain Canuck (Oct 20, 2014)

mbianka said:


> I'd like to experiment with some cheap 12 volt solar controllers to charge each AGM battery individually. That's how my 120 volt Dual Pro Charger works.
> 
> Many people have also gotten away from the concept of the engine/motor as auxiliary propulsion on a sailboat. My experience is that unlike a diesel engine. Electric propulsion complements the sails very nicely without the noise, vibration and heat of a combustion engine. With the addition benefit of recharging the batteries while underway and with solar at anchor. Plus it is easily upgraded. I'm in the process of testing additional amps for when I do electro sail. Got a new generator with remote start and an additional power supply to deliver more amps preserving the capacity of the battery bank. But primarily I use the boat as a sailboat and use the EP portion only as needed.


I agree that electric is an excellent supplement to sailing. I've never used my diesel as a crutch, even when I had it. I bought a sailboat so I could sail, not so I could motor around with all my covers on. Diesel was to get in and out of the marina. Even when the weather turned foul, I always sailed up to the entrance to the marina before switching to diesel.

I prefer sailing to motoring anyway. Sailing is engaging. Motoring is boring.


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## JohnBPrice (Aug 10, 2014)

@postdoc, if you have the money and inclination to try dual electric motors, I think you should try it. Not many people have tried it, so you'll get all the stuck in the mud nay sayers telling you why it won't work or you will cause a rift in the universe if you even try.

My two cents: Twin screws give you reliability if one fails. You can always add a bow thruster too if you like. You can always pull them out and go back to single electric, it will cost money though. The money is the only real reason why you shouldn't do it.

On a different note, I am astounded by the number of people here who hate electric power and all the crazy reasons why it won't work Or is somehow evil. Thousands of people already have electric power, you can order it as an option on new boats or buy electric repower systems. It clearly does work. Sure it has benefits and detriments, but every system on a sailboat does. The best thing to me would be that it is quiet. If I wanted to motor around with the roar of engines and have a motoring range of hundreds of miles I'd buy a power boat.


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