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Old 21-07-2011, 09:13   #46
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Re: Electric Propulsion

This won't work. That won't work. You can't cruise with that. Really? How about the people who cruise all over the world with no engine at all? Is that impossible, too? It is all about what works for you, and how much of the world's resources you are willing to spend for your own convenience and/or pleasure. How much engine time do you NEED? That is a different question from how much you want. Since many marinas will not allow sailing in and out, and if you are using marinas, you need power in and out. If you are working in the morning and need to be home, you need power for that. Will electric work for these purposes? Of course it will. All the rest is convenience.
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Old 21-07-2011, 09:32   #47
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Re: Electric Propulsion

  1. Regenerating under sail will slow you down.
  2. A correlary is that it will also reduce pointing, by changing the lift to drag calculation.
  3. The propelor design for drive and regeneration are a bit different. the efficiency of one will suffer.
  4. I doubt the delivered regenertion horspower will be more than 25% of the drive horsepower. Efficiency and slower prop speed, unless the prop is huge, in which case it better lift.
  5. I hate sailing slow. It would feel like having sails mistrimmed.
  6. Regeneration isn't going to help when the problem no wind.
  7. Recharge at anchor? Most cruisers have solar and wind power just enough for house uses. Sounds like we're going to lose a lot of deck space.
It seems there is never a free lunch. Shame. I would like the quiet. Truth is, I can do that already, sailing.
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Old 21-07-2011, 10:04   #48
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Re: Electric Propulsion

Quote:
Originally Posted by fastcat435 View Post
All I can say is come and join for a sail ( and motor experience )
So far 3 independent sailing magazine's have tested our system and found it to work well.
Yachting monthly September issue 2010
Yacht magazine January issue 2011
Waterkampioen May issue 2011
Hi Fastcat.

I do believe your system works and very well and there seems to be ample evidence to prove that. The problem for me and it seems a number of others is whether the system will work for their boat and their needs.

In my case I have a few concerns.

1. Cost. I'll have to see if my lottery ticket pays off. Otherwise it is really difficult to justify the difference, especially when I look at the other trade offs.

2. Range. I do prefer to sail and have done so for years. Unfortunately at this time I don't have the luxury to not work so have time constraints on cruising. I just cannot afford to sit for a few days waiting for a fair wind. Also, cruising the ICW you just have to motor for long stretches.

3. Power. I do not see a system anywhere on the market that will give the same power output as a 58 HP diesel.

4. Did I mention cost?
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Old 21-07-2011, 10:10   #49
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Re: Electric Propulsion

Totally agree on inefficiences of using the prop for electric generation. Especially on a boat less than 50 feet LWL. The drag at low speeds is very high as is the resistance to spinning the prop; I suspect you'd need at least 6 knots of downwind speed to get worthwhile generating ability. And as 'thinwater' pointed out, this is an especially bad idea for windward work.

On the other hand, an arrangement like an outboard motor that could pivot down when the conditions are right would be a neat trick. Sort of like a Torqueedo in "reverse". Troublesome issues might be watertight integrety and the weight of the assembly on the transom. Has anyone seen this done?
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Old 21-07-2011, 10:26   #50
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Re: Electric Propulsion

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Originally Posted by Billy Higgins View Post
Totally agree on inefficiences of using the prop for electric generation. Especially on a boat less than 50 feet LWL. The drag at low speeds is very high as is the resistance to spinning the prop; I suspect you'd need at least 6 knots of downwind speed to get worthwhile generating ability. And as 'thinwater' pointed out, this is an especially bad idea for windward work.

On the other hand, an arrangement like an outboard motor that could pivot down when the conditions are right would be a neat trick. Sort of like a Torqueedo in "reverse". Troublesome issues might be watertight integrety and the weight of the assembly on the transom. Has anyone seen this done?
Like this for instance ?

so we can do away ( almost ) with the next picture ?
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Old 21-07-2011, 10:38   #51
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Re: Electric Propulsion

Quote:
Originally Posted by skipmac View Post
Hi Fastcat.

I do believe your system works and very well and there seems to be ample evidence to prove that. The problem for me and it seems a number of others is whether the system will work for their boat and their needs.

In my case I have a few concerns.

1. Cost. I'll have to see if my lottery ticket pays off. Otherwise it is really difficult to justify the difference, especially when I look at the other trade offs.

2. Range. I do prefer to sail and have done so for years. Unfortunately at this time I don't have the luxury to not work so have time constraints on cruising. I just cannot afford to sit for a few days waiting for a fair wind. Also, cruising the ICW you just have to motor for long stretches.

3. Power. I do not see a system anywhere on the market that will give the same power output as a 58 HP diesel.

4. Did I mention cost?
Hallo Skipmac

1. You are right , the cost ( unfortunately ) are still very high but it are coming down. ( specially Lithium batteries)
I hope you win the lottery
2. Range is not a problem is, you add a generator ( range extender )

3. The power output of a 20 Kw electric motor is comparable to a 58 HP diesel

in the next 2 months we are doing an installation of 2 x 20 Kw retractable Motogens on a 61 Ft Catamaran and this will give the cat a speed of 9 knots max , that compares well with a double 60 HP diesel installation.

4. Yes you did mention the cost and again yes these are still high, it all boils down to numbers of production.

Greetings
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Old 21-07-2011, 10:43   #52
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Re: Electric Propulsion

Quote:
Originally Posted by fastcat435 View Post
Like this for instance ?

so we can do away ( almost ) with the next picture ?
The propellors going up and down is automated through reading the battery voltage? Looks like a pretty nice system. Should make those worried about drag a bit happier.
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Old 21-07-2011, 10:54   #53
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Re: Electric Propulsion

I really like the look of the Motogens. Are these commercially available yet?
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Old 21-07-2011, 11:37   #54
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Re: Electric Propulsion

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4. Did I mention cost?
I saw this mentioned before also, but I don't see where the cost automatically favors the diesel. For my boat it's a Thoosa 9000 vs a Yanmar 3GM30F.

Thoosa might be $7800 + 2k for 4 GPL-4DL AGM batteries for 210AH @ 48v. 200 AH installs are pretty typical. So that's around 10k. Install should be pretty easy to do solo, except for maybe attaching to the prop shaft and handling any fiberglass/woodwork needed for the engine mounting.

With the Yanmar I can get a rebuilt one for maybe 5k, but I believe a new one will run me closer to 7k? It's hard to get prices for them online. This doesn't replace my transmission, fuel tank, and so on which will also need servicing at some point too.

Ongoing maintenance on the Yanmar would be oil changes done twice a year, impeller changes, fuel filters, belts, gaskets, etc etc. Could easily be 1k a year for the general wear and tear stuff.

With the electric you're changing out the batteries, say, every 7 years? So that's 285 a year if the price stays at 2k for lot of them. You'll also have to replace a belt every 3 years and the brushes every 3000-6000 hours.

But then the diesel also has a transmission, electrical system, fuel tank, fuel costs, etc etc.

Over the long term the costs seem comparable. Up front the initial layout of the diesel would be cheaper(unless I needed a lot of labor installing it), but I think the electric wins when it comes to ongoing maintenance. I'd also think the electric would be less prone to critical break downs that cost a lot of $$ to fix, but who knows. There aren't many of them out in the field.

Throw in a big generator and ya, costs go up and up and it sort of begins to defeat the whole idea of going electric(no more dealing with oil changes, fuel costs and so on). But on the plus side you gain a generator which has other uses.

I think(hope) electric car battery tech will drive this on boats. If I could go Lithium I could get about 400 AH for the same weight and deeper discharge. That would be maybe 3x the range? So instead of 2 hours at a high speed you'd get 6. Maybe a whole day or more at a bit slower speed. That might make it reasonable to marina hop your way along the coast. Just plug in at night and be recharged in the AM. But an install like that today would be something like 15k just for the batteries.

If the price of that goes down or the battery tech improves even more(more AH per pound and better discharge down tolerance), then electric really starts to look more and more reasonable for your average cruiser, especially if fuel prices keep going up and up.
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Old 21-07-2011, 11:48   #55
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Re: Electric Propulsion

The real world: Left SF for Hawaii. On the third day out after little progress toward Hilo because of light winds on the nose for most of the time, finally picked up decent NW winds. Unfortunately, a bolt fell out of the self steering vane causing it rip out of the transom. When the vane let go, it tore out most of the transom surrounding the backstay chain plate. No choice but to turn back to SF, a 180 miles to the East and hope the thin piece of fiberglass still holding the backstay chainplate doesn't let go. Have 260 watts of solar generating capacity but weather is overcast so putting out next to nothing.

Since I had the trusty diesel and ample fuel, turned on the engine and powered back without incident. Total cost in diesel was a couple of Gerry Cans. If I'd had only an electric motor, could still be sitting out there unless I'd converted the boat's interior to battery storage and spent a fortune on batteries. Could have bought a genset and charged the batteries via that but it would have cost me diesel and the additional cost of the genset and lost space to store it and it's fuel. As far as efficiency, you'll have a hard time convincing me that converting diesel fuel into electricity to run an electric motor is more efficient than a diesel motor running directly to the prop.

Another example: Sailing to the Marquesas when we run into the ITCZ. Temps close to 100, water temp near 90, humidity through the roof. In short, it's miserable where just the act of breathing causes you to break out in a sweat. Add a 10 foot ocean swell from a storm in the southern ocean and you've developed a new perspective on Coleridges poetry. So I spend 8 hours using every trick I know of to get the boat to sail the four miles to the horizon to inspect something I see floating out there. It turns out to be nothing but a piece of plastic trash. Jump in the ocean to cool off but water is so warm it's no relief and we feel worse when we get out because the air is so saturated it won't evaporate the water from our skin. After 24 hours of rolling and banging, constantly dripping in sweat, wife is eyeing the cutlery in anticipation of making me pay for getting her into this. Had little choice if I wanted to wake up from my nap but to start the engine and power for 36 hours straight hours till we finally picked up some wind. Once again, without humongous battery capacity, electric propulsion would have caused another mysterious disappearance. Solar panels might have helped but only a Catamaran has the realestate to hold the number of panels that would be needed.

Yes you can go completely without engine propulsion. The Pardey's are great proponents of this. I hear rumors that they have accepted tows to get into port and are not averse to begging for them. If your desire is a non stop around the world voyage in the roaring forties, an engine isn't a big asset. If you are talking the world of the typical cruiser, an engine is real hard to get by without. Moistessier sailed Joshua for many years without an engine till a friend gave him a small diesel. He said it was the best thing that ever happened to improve his cruising life. Anchorages and ports that had been closed to his engineless boat suddenly opened up and his life was much the richer for it. Yes you can do it with electric power but you are limited by the capacity of your batteries so better hope everything will be less than 24 hours away.

If you really must feed the green envy consuming you, get a system that will give you a least 48 hours at 6kn. Less than that and you are cheating yourself. If you have to add a diesel generator to get decent range, you'd be better off going with diesel propulsion in the first place.
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Old 21-07-2011, 12:04   #56
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Re: Electric Propulsion

4. Did I mention cost?[/QUOTE]

The cost parameters are changing rapidly--have you been to the fuel dock lately??

In Kauai, diesel generated electricity from the co-op grid now costs a whopping 45 cents per KwHr. I ran some numbers for solar voltaic systems, and figured you could switch to solar and cut your bill in half, even without assuming any further increases in oil prices. Solar panel prices are finally coming down, and future price cuts are probable.

If you open up the throttle on your 60 hp diesel, you will burn 3 gal/hr, or $12-15/hr at current prices. That's $290-360 for motoring 24 hrs. Do the math at $10/gal,coming soon...
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Old 21-07-2011, 13:26   #57
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Re: Electric Propulsion

Does this setup make sense ?

10KW Genset
2 KW Solar Panels
40KWh Li Batteries (what voltage ?)
2x20KW El. motors

Batteries
- 30 min full power
- 1h half power
if 50% discharge allowed

Solar panels don't provide enough power to support genset or batteries

So if batteries are empty the genset could provide at least 2x5KW

Bottom line - is a larger genset required for long term motoring ?
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Old 21-07-2011, 13:52   #58
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Re: Electric Propulsion for a larger boat

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Apparently ICE and electric motors aren't rated the same. The 58hp diesel engine is rated at its Max (Peak) HP while the 24hp electric is its Max Continuous Power.

An electric can burst past that rating though.
Fine.

Can you PLS explain to me how the ratings CAN be compared. Say, a 58hp diesel, how much MCP will it typically develop?

And why will a manufacturer entering a new market rate their products in a way that is not outrightly understandable to vast majority of potential clients?

b.
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Old 21-07-2011, 14:56   #59
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Re: Electric Propulsion

I have electric power, and I would not consider using diesel or any other fuel for that matter. Yes I recently crossed the pacific. I spent $800 on batteries, I have 1000AH at 12v. I got free electric trolling motors, they are old and not that efficient, but free. I have solar panels that cost $1.75 per watt. I can motor for hours.

Some misconceptions to address:

Electric is _not_ more expensive. Etek motors cost a fraction of a diesel with the same power. I am considering going that route, but I prefer free motors.

Electric is _more_ reliable than diesel/gas. Someone earlier posted they were not,, this just isn't true. I wonder what is more likely to break down, a diesel that has to be started with an electric motor, or just an electric motor.

Electric has _more_ range than diesel. This depends how you measure range, but with electric you can recharge your batteries under way, and motor forever on solar power. With diesel you run out of fuel, and correct me if I am wrong, but you cannot produce diesel fuel under way.

Electric has _more_ power than diesel. For short bursts, nothing beats electric for power/acceleration. As far as melting the motor.. get a temp sensor. You can run electric at 10x its rating for 30 seconds. The limiting factor is melting copper. This is exactly what you need to get out of bad situations.

Botttom line, electric is better. Everyone I see using diesel could have gone electric for less money, and still used it the same way they are using the diesel.
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Old 21-07-2011, 15:00   #60
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Re: Electric Propulsion

One reason is that the electric motor rating is often for continuous output. An electric motor can, unlike a marine diesel, greatly exceed it's rated power for considerable time. Especially series-wound motors. It depends entirely how long it takes to heat up enough to melt the insulation and fail.

In a marine application I would think only the continuous rating is useful. Who would want to risk destroying the motor?

The only scenario that a diesel-electric system will save fuel over a direct drive system is at quite low output, or in intermittent use. That is how hybrid cars accomplish fuel savings. Autos operate much of the time far under their maximum power. Boats and yachts do not.

If I was setting up a catamaran for long-range cruising I wouldn't worry about a small fuel savings. What I would worry about is installing a very heavy system better suited for a locomotive. Diesel-electric just doesn't make sense to me at this time. In any boat. (They do not use diesel-electric in freight shipping, BTW.) And the slick claims without independent unbiased evidence, and little engineering basis, haven't impressed me either.
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