Pleased with Electric Propulsion

[skipmac]

Originally Posted by Blue Stocking

We cant even get various national bodies to agree on something as infantile as wire color schemes. Ridiculous!!

Or a standard color scheme for buoys and markers. Or which side of the road to drive on. And of course metric, will the US ever change over.

[Blue Stocking]

Originally Posted by skipmac

Or a standard color scheme for buoys and markers. Or which side of the road to drive on. And of course metric, will the US ever change over.

HAHA!--look at my last comment on the "Elle" thread

[Sand crab]

I've read numerous blogs (bumfuzzles and others) about being becalmed for days. So they motored for days. I'll go electric when they "invent" a system that can do this at normal cruising speeds of say somewhere around 5 to 10 knots without the extra expense, weight, and reliability issues. End of story. BOB

PS What's a metric?

[mbianka]

I'm just about to finish up my fourth season with electric propulsion on my 30 foot 8 ton sailboat and feel it is one of the best improvements I have ever made. My 27 HP diesel died and I went looking for alternatives and came upon electric propulsion and am glad I did.
THE BIANKA LOG BLOG: Going electric: Part 1: The why and how
My maintenace costs are way down and sailing enjoyment is way up. Also hard to put a price on always having a clean smelling bilge and engine area. With solar panels, 48 volt wind generator I just get a kick of sailing along and making fuel (energy) at the same time:
THE BIANKA LOG BLOG: HAPPY AT THE HELM!
I can also move my boat at three knots using just 900 watts of the 1600 watts available from my Honda 2000 generator without even drawing any amps from the 10 kw battery bank. The Honda will run 5 1/2 hours using a little over 1 gallon of gas in it's fuel tank in that mode.
This year I also discovered the regen ability of my ASMO MARINE system. I was electro sailing i.e. just turning my prop enough to negate the prop drag when I noticed that the amp meter was going positive as the boat started to hit 6 knots:
THE BIANKA LOG BLOG: ANOTHER ADVANTAGE OF ELECTRIC PROPULSION: REGEN
Call me a very happy sailor when I discovered that happening. Also after my 48 volt battery bank is charged up I can sit at anchor for a few days my boat my EP system will still be making energy with the solar and wind generator. Energy I can use to run my laptop or other devices while I let the 12 volt panels just keep the freezer running. It also serves as a backup to it as well.
I don't begrudge someone who wants to stick with a diesel in a sailboat. But, for me my electric propulsion system has been much more quieter,cleaner, reliable and requires almost zero maintenance compared to my former diesel so maintenace costs are way down too. Plus I can upgrade much easier as new technologies (motors, batteries etc..) come along if I want too. But, I really don't see the need for it because my current system fits so well with my needs. I just would never go back to diesel after my experience of four years with electric propulsion on board.

[Target9000]

Don't worry bub. I'll burn enough diesel for both of us.

[David M]

75 amps times 12 volts is 900 watts. There are 745 watts per horsepower, meaning the motor consumes 1.2 horsepower worth of electricity. This means the propellers output is roughly around one horsepower after losses from motor inefficiency, heat and friction.

I'm glad to hear your boat does exceptionally well with effectively one horsepower pushing a three ton boat. Were this to scale up to a ten ton boat this would be the equivalent of a 3 horsepower motor or 6 horsepower for a 20 ton boat.

[nwdiver]

I have looked at this for a 41 foot sailboat, I looked at it differently, I just want power ever once in awhile when I really need it. I started with the premise “this is a sailboat” so I was not looking for a diesel replacement. The technology is not there yet. With 450 watts of solar I could live normally with frig and water maker, lights and com gear, fine by me. I was looking at this electric motor as an addition to my sailboat, so I was going to sail as if I didn’t have any propulsion, this may not be practicable for 90% of people but there are engineless boats out there. I sailed a whole season of weekends and holidays in my C&C 38 with only 6 hours of engine time which had to do this schedules and 6-8 knot tidal passes.
If you really were wired into your system, you would row it and not have propulsion, looking for all day at 3 knots I can do that by sail, get off your soapbox and tell us about your system share ideas not bravado, why would you want to use you motor all day and not your sails???

[seandepagnier]

So many replies quickly shows great interest in electric propulsion. To answer a few questions. I got a free motor from orange county outboards. They were very nice but since they specialize in gas outboards they offered me an electric one which they said they didn't have a use for. Basically I have electric trolling motors for fishing boats. The minnkota and motorguide variety. Very cheap on the used market. Not very efficient, but they are way more efficient than a diesel. I use one on my kayak and I can go 4 knots consuming less than 300 watts.

To clear up some things on the 32 amps. Yes I have a real amp meter and I measured this value. I have 530 watts of solar panels which should be able to output 44 amps, but as we all know solar panels do not live up to their ratings. I do not have peak power tracking. There are 2x 115w panels on either side, and 6 50 watt panels which I tie on. I had 13 50w panels but I sold 7 of them for $$ :-P It was ridiculous to have that many on a bristol 27 anyway, basically the entire deck is covered and no where to walk. I get more than 10 amps when it is overcast which is roughly enough to move at 1 knot. When combined with light air sails, I can get up double the speed I could sail on this minimal amount of power. I cannot motor for multiple days, and I do not need to. I do not motor offshore, it doesn't make sense. I do not motor against headwinds, if there is wind I can sail. I make passages faster than many people who use engines. I averaged 135nm/day on the last passage. I can sail at 4 knots in 4 knots of wind. The motors are for dead calm, and for getting on/off tricky docks when there is not room to tack.

I did have a wind generator, but it was an air-x, noisy thing, and the slip rings are messed up after 2 years. Then the steel pipe broke and I took it down. I dont really plan on putting it up again, the power output was a dissapointment. The boat is small for it, and I really need a simple way to completely stop it to avoid wind loading so I can sail upwind better. If I got a windgen again, I would look for something which can produce 20 amps in 15knots of wind. I dont think one exists and the blades would be huge, so it would need to be able to lock and not spin at times.

As for regeneration from the motors under sail. I looked into this as well, but unfortunely, the power available at the speeds I sail (5-6knots) is relatively low, and not really worth the effort. On a vessel which can achieve higher speeds (9-10knots) it is very likely worthwhile. I might be able to use a funnel in the water to increase the speed of water to a prop, but I have not gotten to this yet. Also, most propellers for driving a boat are cupped the wrong way around for generation. To get optimum efficiency (minimum drag maximum power) a different propeller should be used for driving the boat and for regeneration.

As for battery weight. You already have a ton (probably 2 or 3) or more of lead in the keel. Lead acid batteries make good ballast. My boat sails faster than before in strong winds due to increased waterline and better righting moment. In light airs, I can use the batteries to give more thrust.

Originally Posted by mbnka

I don't begrudge someone who wants to stick with a diesel in a sailboat. But, for me my electric propulsion system has been much more quieter,cleaner, reliable and requires almost zero maintenance compared to my former diesel so maintenace costs are way down too. Plus I can upgrade much easier as new technologies (motors, batteries etc..) come along if I want too. But, I really don't see the need for it because my current system fits so well with my needs. I just would never go back to diesel after my experience of four years with electric propulsion on board .

I want to go to 48v too. I am stuck at 12 because of the solar panels. How do you charge them off solar? Do you have 48v panels? Do you have a boost regulator?

Originally Posted by David M

75 amps times 12 volts is 900 watts. There are 745 watts per horsepower, meaning the motor consumes 1.2 horsepower worth of electricity. This means the propellers output is roughly around one horsepower after losses from motor inefficiency, heat and friction.

I'm glad to hear your boat does exceptionally well with effectively one horsepower pushing a three ton boat. Were this to scale up to a ten ton boat this would be the equivalent of a 3 horsepower motor or 6 horsepower for a 20 ton boat.

This is the wrong calculation. You don't double the power when you double the weight. The weight increases as the cube of length, the wetted surface area increases with the square of length, and therefore if you double the weight, raise 2^(2/3) power and you will see you only need 1.5x the power.

Also, my boat is not exceptional. My propellers are inefficient as are the motors and flooded batteries. The thing to keep in mind is that most diesel propulsion systems on small boats are exceptionally inefficient. So much so that they require 10x the horsepower to equal an efficient electric drive system. That's right, <3% of the energy in the diesel is actually producing thrust to propel the vessel. Most of the energy turns into heat, and turbulence and wake which is wasted energy. Now maybe you can see why I consider diesel foolish. All that oil could be used to make cheap synthetic lines and sails for everyone, but instead people are wasting it in their inefficient engines. Did you read about the 40ton submarine which can go 3 knots on only 1/4th horse power? look on google

[mbianka]

Genkosenator:

Yes, I have two 48 volt solar panels that also are part of my solar Bimini. Usually they will charge about 2% per day and that is with them partially covered by the boom. I'm not that anal to keep moving the boom to clear the panels completly. I know I would get more out of them if I did. I do like having the wind generator on board too as well as the Honda 2000. I like the three legged stool approach to charging.

[downunder]

Originally Posted by geckosenator

Since getting free electric motors, and using the motors in california, cook islands, samoa, tonga, and now new zealand, I can say any other propulsion system would have been a headache. Simply flip of a switch and instant power. No maintainance, no fuel, no oil. Only 1 moving part. I have two motors for reliability, and to get more power with the motors I obtained. Combined consume a total of only 75 amps at 12 volts. Since I get 32 amps off solar in direct sun, and have 832 amp hours, I can motor all day going 3 knots. I can motor against 30 knot wind and make headway (if only slight) At anchor the batteries recharge, and are useful for cooking in electric ovens/stoves as well as everything else electrical.

I wanted to bring this up again because I see so many foolish people out there with diesel engines, and they are doing a great dis-service to us all. I wanted to point out there is a better alternative and it works, it is much cheaper, and people are doing it. Also, the laws of physics clearly show that this system works even better scaled up to larger vessels. Mine is only 3 ton.

Please reply with any comments/questions, but if you are going to tell me you need diesel so you can motor 800 miles against 30knot winds, I will kindly ignore you.

I the area I operate strong currents are a fact of life. A reliable propulsion system is a key safety factor without compromise.

Electric systems sound good and perhaps in 5-10 years time they may be a option.

Meanwhile keep up the experimentation.

[David M]

Originally Posted by geckosenator

This is the wrong calculation. You don't double the power when you double the weight. The weight increases as the cube of length, the wetted surface area increases with the square of length, and therefore if you double the weight, raise 2^(2/3) power and you will see you only need 1.5x the power.

I understand what you are saying about wetted surface area and I agree.

My calculations are correct though. Potential times current (for DC) equals power in watts. There are 745 watts per horsepower. This makes your motors effective output at the propeller after losses from inefficiency about one horsepower.

I was scaling up in proportion to mass, not wetted surface area.

Is one horsepower for a boat that displaces 3 tons enough for everyone? Is 3 horsepower adequate for a boat that displaces 10 tons? Is 6 horsepower adequate for a boat that displaces 20 tons enough for most people? Most people really do need to run their boats at more than a knot or two or even three. With all due respect, I think most prefer to be able to run their boats closer to hull speed when needed.

[David_Old_Jersey]

Originally Posted by David M

Most people really do need to run their boats at more than a knot or two or even three. With all due respect, I think most prefer to be able to run their boats closer to hull speed when needed.

Does everyone really need to?

In the good old days (before Marine engines shrunk in size physically / yacht design changed to accomadate more powerful engines) yachts that could travel at hull speed under power were called motorsailors. The others were Auxiliary Sailing Vessels, with engine never intended to be used on passages........and sized / powered accordingly.

I don't beleive there were mass sinkings back then

Being able to travel at hull speed (at least sometimes) would be very useful - but essential for everyone? Not so sure. Planning passages around an engine does (to me) kinda miss out on the point of having a Yacht.

Back to the future? with an "Auxilliary Electric Yacht".

[David_Old_Jersey]

Now I know how sailing / boat newbies feel

Been mulling over all things Electric........

From what I understand, there are 4 main elements to an installation:-

1) the electric motor

2) the Batteries

3) A Controller that gets the battery power from the batteries into the Electric Motor (without frying anything!).

4) A Controller that gets electric into the batteries (Solar / WInd / shorepower) without frying the batteries........that end of things exactly the same as on a diesel powered boat?

"Controller" is my word From various photos that looks like it may cover a few mysterious (to me!) boxes............but that one for later!

Ok, my questions:-

1) On the basis that Electric Power is not yet where I would prefer it to be (performance, range and re-charging), but that will (likely / hopefully!) improve in future years...............would I be on the right track in beleiving that (all things being equal) I could upgrade any of the 4 main elements as and when the improvements merited that - without having to install a whole new system (1 -4) in one go? (although that may well be the result over time).

2) Where does the oomph (Torque / thrust / power) come from? . I am struggling to understand whether the limitation is in the Electric Motor or lies elsewhere (or everywhere ).

[Adelie]

Originally Posted by David_Old_Jersey

Now I know how sailing / boat newbies feel

Been mulling over all things Electric........

From what I understand, there are 4 main elements to an installation:-

1) the electric motor

2) the Batteries

3) A Controller that gets the battery power from the batteries into the Electric Motor (without frying anything!).

4) A Controller that gets electric into the batteries (Solar / WInd / shorepower) without frying the batteries........that end of things exactly the same as on a diesel powered boat?

"Controller" is my word From various photos that looks like it may cover a few mysterious (to me!) boxes............but that one for later!

Ok, my questions:-

1) On the basis that Electric Power is not yet where I would prefer it to be (performance, range and re-charging), but that will (likely / hopefully!) improve in future years...............would I be on the right track in beleiving that (all things being equal) I could upgrade any of the 4 main elements as and when the improvements merited that - without having to install a whole new system (1 -4) in one go? (although that may well be the result over time).

2) Where does the oomph (Torque / thrust / power) come from? . I am struggling to understand whether the limitation is in the Electric Motor or lies elsewhere (or everywhere ).

I think 1. is the really key question that people are wrestling with right now. My answer is that the batteries are the big issue and the means of recharging them. The power to weight and power to size capacity of currently economical batteries is to small. Any system that will let you motor at hull speed for 12hr will take up too much room in the boat and weigh like sin. Li-ion batteries seem to go a long way towards addressing this problem but suffer from cost issues, last I checked a 320A-hr LiFe-Po battery (260A-hr usable) weighs about 65lb, takes up the same room as a 100a-hr Pb battery and costs about $6000. A Pb battery bank of 780 A-hr (240A-hr usable) would weigh about 450lb, and cost $600-1000. Even a bank of LiFe-Po batterie would be hard pressed to give you Hullspeed for 12hr in a reasonable volume and weight.

Unfortunately the battery has effects on the rest of the system but the charger more than the other part. Whatever battery you get the charger will have to be designed for that battery, both so voltage is properly controlled and so that temp and charge rate and whatever else important to that particular battery is controlled.

You would probably get away with installing a motor and controller now. Motor technology is pretty mature, and so is the controller technology.

The problem is picking a voltage that will work with whatever battery technology comes along. As a guess 48v will probably be supported and seems to be the popular voltage currently. The other thing to consider now is that if you buy a current system it will probably be optimised for current battery technology and will be undersized for later when battery technology improves.

The current systems seem to be designed for daysailing and lower demand uses. Upping your demand later when batteries improve enough to let you do that may be hard on the motor and controller, though I am very uncertain of this.

The current limitation on oomph in the motors is related to the batteries. They could install larger motors and get a lot more speed and push out of them but that would be facilitating abuse the batteries by users. The current generationn of motors seems to be tailored to stay within the limits of the currently available batteries. Bigger motors with current batteries could get you a lot more oomph at the cost of very short running times and higher motor weight. The motor weight isn't that big a deal, but the range and speed issues are for most people.

Current users are generally happy to modify their boat usage in order to change to the system. Then again most users are daysailing and overnighting, they are ok with limited speed and range under power in exhange for savings in weight, noise, complexity and fuel costs.

My sense is that those who now go crusing with electric are people that would happily go engineless or are at least on the fence about it.

My feeling is that if you want to go electric now there are 2 ways for cruisers to go right now.

A. Keep your engine, add an extra battery or 2, get a solar panel or 2 and use a trolling motor on an outboard bracket. All together this should be under $1k. This system will get you in and out of a marina or an anchorage in moderate weather with minimal current against you. If you need to go long distances or against a current you still have the engine.

B. Replace your current engine with one sized to push your boat at economy cruising speed (4-5kt), piggy back an electric motor system onto the propshaft. Add batteries, panels and controller. Now you have more oomph to get in and out on electric against a moderate current or a fair amount of wind, not a lot of oomph but more than the trolling motor. For long distance powering the diesel pushes you along operating at it's most economical load, and when you need a lot of push all at once the engine and motor run together, you just can't have that much power for long. This is the expensive option, figure $10k.

[mbianka]

Originally Posted by David_Old_Jersey

Now I know how sailing / boat newbies feel

Ok, my questions:-

1) On the basis that Electric Power is not yet where I would prefer it to be (performance, range and re-charging), but that will (likely / hopefully!) improve in future years...............would I be on the right track in beleiving that (all things being equal) I could upgrade any of the 4 main elements as and when the improvements merited that - without having to install a whole new system (1 -4) in one go? (although that may well be the result over time).

2) Where does the oomph (Torque / thrust / power) come from? . I am struggling to understand whether the limitation is in the Electric Motor or lies elsewhere (or everywhere ).

Dave:

1) Yes one of the nice features of an electric propulsion system is it's ability to upgrade it very easily. That's one of the things that drew me to it. I thought through all ramifications about going electric. The limitations of a battery bank for power. I decided that I would go with a cheap sailors hybrid system using the Honda 2000 for charging and some motoring. My thinking was I could always install an in board diesel generator if it did not work out. But, I find the Honda meets all my needs and then some. I could buy five Honda generators for the price of on in board diesel. At 47 lbs carrying a spare generator is not a big burden if one wanted to have one. Hell a lot of boats with diesel engines have Honda 2000 on board too.
I think the first upgrade will probably be in the battery area. I went with AGM batteries because I wanted to be able to replace them easily no matter where I was cruising if I needed to. Lithium Ion were IMO way over priced for my needs I keep an eye on the technology. But, I doubt I will switch unless prices come way down. I might also up upgrade the battery charger to one putting out a few more amps when motoring without drawing current from the battery bank and therefore a little more speed. But, I really don't feel the need to spend the money at this point. I could also add an additional power supply and achieve the same thing. So there a number of ways to achieve what you want with EP.

2) The limitation in an EP system is the battery bank. But, there are ways around this. I operate with conservative philosphy in this regard. I will operate under electric battery power alone until the battery bank has dropped to about 80%. I then usually fire up the Honda to take over the propulsion power. I do this usually only if there is no wind which does not happen often but, it does happen. I motored for ten hours one windless day this summer just using the Honda. Though often when I'm using the Honda the wind will start to pick up and then some of the power that was running the motor starts to recharge the battery bank. Often by the time I reach my destination the battery bank is back up to a full charge and I never have to fire up the Honda again while at anchor. My solar and wind generator keep things topped up until it's time to weigh anchor again.