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Old 13-02-2012, 13:41   #76
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Originally Posted by abh
Alberto must be nuts, with the reefs and all.
I want to hear more from Alberto. What his system entails, how often he motors and what he uses to recharge his batteries. If you use your boat as a day sailor and can tie up to the dock every night to recharge that's one thing. If you cruise and live on the hook that's totally different. I'm all for electric I just don't think the technology or maybe affordable technology is there yet.
Please prove me wrong.
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Old 13-02-2012, 13:56   #77
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Re: Electrical Propulsion vs Diesel Propulsion

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...Pure electric is as far as your batterybank will last. In most cases not far and therefore impractical for open sea cruising.
Well, I can name a manufacturer or two that state you can run the electric motor for up to 5-6 hours. That seems like a very long time to be exclusively motoring.
There are many sailors who do not even put a motor/engine in their sailing vessels but somehow manage to cross oceans.
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Old 13-02-2012, 14:15   #78
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Re: Electrical Propulsion vs Diesel Propulsion

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Well, I can name a manufacturer or two that state you can run the electric motor for up to 5-6 hours. That seems like a very long time to be exclusively motoring.
There are many sailors who do not even put a motor/engine in their sailing vessels but somehow manage to cross oceans.
That may be, That may be.

Here it is unlawful and to be fined to enter the main harbours and waterways w/o mechanic power.
There is even a law that says that a ship w/o engine can be considered being a wreck. There are of course the exclusions but in general is the man sailing w/o engine our waters and the NorthSea no more than a fool.
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Old 13-02-2012, 14:31   #79
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Re: Electrical Propulsion vs Diesel Propulsion

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Originally Posted by Notpopeye View Post
Well, I can name a manufacturer or two that state you can run the electric motor for up to 5-6 hours. That seems like a very long time to be exclusively motoring.
There are many sailors who do not even put a motor/engine in their sailing vessels but somehow manage to cross oceans.

Well, it's easy to work out. If you have a 48 volt motor, and run it at 4800 watts - about 7 horsepower - you'll need 100 amp/hours of battery (at 48 volts) for every hour of running. But that would drain them 100% which would dramatically shorten their life.

So for every hour of running you'd need to have around 180 amp/hours of lead/acid batteries, or maybe 120 a/h of lithiums. (All at 48 volts remember)

So for 5 hours running you'd need 900 a/h at 48 volts of lead/acid (equivalent to a 3600 amp hour 12 volt battery) or 600 a/h of lithium (equivalent to 2400a/h at 12 volts).

So, it's possible on batteries, but you'd need a lot of them. They'd either be very heavy and very expensive, or quite heavy and extremely expensive.
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Old 13-02-2012, 15:02   #80
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Re: Electrical Propulsion vs Diesel Propulsion

Why are the DC gensets so much lighter than AC assuming we compare apples to apples? Amps to amps. And Deckofficer do you think that Harmony was just too complicated. Would you consider it for yourself now? BTW I incorrectly listed it as a 42'. It is a 46'.
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Old 13-02-2012, 15:03   #81
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Re: Electrical Propulsion vs Diesel Propulsion

A boat designer - I think in Australia - named Robert Barros, designs a 25 foot boat that is allegedly bluewater seaworthy. The boat has a twin keel system and uses auxiliary electric motors for propulsion.
The overall general description for the POP 25 states:
"The Pop 25 requires at least a 4.5 kW electric motor to be propelled at five knots or more. For six to eight hours of continuous operation, with a motor of this working power installed, it requires a battery bank of at least 600Ah If the boat is meant to be sailed on short weekend trips and is stationed in a marina where energy can be supplied from the city’s A.C. system, then there will probably be low risk of getting battery banks flat. If, however, the boat is intended for longer passages, it will require its own means of replenishing the energy supply, like solar panels, wind generator, the motor itself functioning as generator when the boat is sailing, or even by complementing an eventual deficit of supply with a small portable generator.

The Swedish made 4.5kW OZsingle. A compact and clean auxiliary motor.

There are several companies in the US and Europe producing electric motors for small sailboats auxiliary propulsion. Among them, OZmarine , from Sweden, has in its line of products a model that suits well the Pop 25, the OZsingle 4.5kW motor. Another option is the Thoosa 6000, 6kW, produced by Asmo Marine, from Denmark. Even though being a little over-dimensioned, with its 6kW , it affords a higher speed with aproportional increase in consumption.

A third choice is the E-Pod 2000, which differs from other for being totally installed outside the hull. Even though being under-powered with its 2kW, it allows installing two units of them, each one aligned with a rudder, then providing an acceptable speed with the two motors working together besides enhancing maneuverability."

So this is in line with the 600 a/h you calculated. But then again, this is for a small boat with a 6330 lb displacement. Kind of small by any standards.
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Old 13-02-2012, 15:23   #82
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Re: Electrical Propulsion vs Diesel Propulsion

For the folks that like to roll there own, I have a number of links to EV businesses that I have purchased from for my projects. Here is just one....
Cloud Electric, LLC

Bob Sandcrab,

I do not know why Harmony's first system didn't work for them other than just maybe they are the type, when they motor, are at full propulsion. I know a few that run their diesels to the stops, but for me that is too noisy and sucks too much fuel. Maybe they thought since there was no noise, then full speed at a continuous basis was their SOP.
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Old 13-02-2012, 16:56   #83
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Re: Electrical Propulsion vs Diesel Propulsion

Quote:
Originally Posted by Notpopeye View Post
Well, I can name a manufacturer or two that state you can run the electric motor for up to 5-6 hours. That seems like a very long time to be exclusively motoring.
There are many sailors who do not even put a motor/engine in their sailing vessels but somehow manage to cross oceans.
"for up to 5-6 hours . . ." Heck, I run my diesel on long passages for up to 5-6 days - around the clock. I do keep 7 days worth of fuel onboard so that is my limit.

The days of pure sail only passages from port/anchor to port/anchor is pretty much gone. You can find plenty of books (history) of that sort of thing, but for modern cruisers (not day sailors) an engine is as basic as the mast and sails.

I do believe everybody can agree that electric propulsion is mature enough especially since most modern cruise ships and other "biggies" all use it. But getting sufficient power to those big electric motors still requires a diesel engine/genset.

The electric storage and power control systems for small yachts (under 100 feet) is currently the weak point. When enough work is done by the dreamers who put these systems on their boats and the demand for reliable systems is sufficient to drive the market, then, IMHO, electric propulsion for private small yachts will be the norm.

So for those dreamers wanting to install the systems in their boats, I applaud you, as you are blazing the trail and doing the R&D that someday will lead to reliable, economical electric propulsion systems for the rest of us.
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Old 13-02-2012, 17:27   #84
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Re: Electrical Propulsion vs Diesel Propulsion

It is encouraging to see the trend here ... a few years back anyone suggesting electric propulsion for a boat would ave been derided or ignored. There are still some diesel adherents, of course, and their observations that the technology needs some developing still are, (and always will be,) accurate.

There have been a series of good articles by Nigel Calder in Cruising World and elsewhere on this general topic. My only additional comment is that he focusses on only two battery technologies -- Pb acid, especially the thin plate pure lead or TPPL variety (if you are still using the old wet cells you probably will cling to your diesel as well,) and the new Lithiums, which have not yet come of age in my and his) opinion.

The technology he neglects is Nickel Metal Hydrdide (NiMH). These are rugged, simple, reliable, more or less idiot-proof and have about the same power per unit volume as Lithium and power per unit weight between Lithium and Lead. We use them in our in systems and so does Toyota, Nissan and others in hybrid electric cars.

The comment about turbines is right on target. When will e able to buy the equivalent of a small Honda gas generator with a turbine (one moving part) instead of all the clap-trap junk of the Otto-cycle piston engine?
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Old 13-02-2012, 17:35   #85
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Re: Electrical Propulsion vs Diesel Propulsion

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Originally Posted by osirissail View Post
The days of pure sail only passages from port/anchor to port/anchor is pretty much gone. You can find plenty of books (history) of that sort of thing, but for modern cruisers (not day sailors) an engine is as basic as the mast and sails.
Can't agree entirely. We quite often sail anchor to anchor, or more often only use the motors for anchoring (up and down)..

But there's no denying that we also sometimes motor sail all day. Sometimes there are deadlines nature imposes - getting across a barred enterance while the tide is right, for instance.

For day sailors batteries and electric might work pretty well, but IMO for cruising you need either a genset to go with that or conventional motor(s).
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Old 13-02-2012, 17:42   #86
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Re: Electrical Propulsion vs Diesel Propulsion

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Originally Posted by kefroeschner View Post
It is encouraging to see the trend here ... a few years back anyone suggesting electric propulsion for a boat would ave been derided or ignored. There are still some diesel adherents, of course, and their observations that the technology needs some developing still are, (and always will be,) accurate.

There have been a series of good articles by Nigel Calder in Cruising World and elsewhere on this general topic. My only additional comment is that he focusses on only two battery technologies -- Pb acid, especially the thin plate pure lead or TPPL variety (if you are still using the old wet cells you probably will cling to your diesel as well,) and the new Lithiums, which have not yet come of age in my and his) opinion.

The technology he neglects is Nickel Metal Hydrdide (NiMH). These are rugged, simple, reliable, more or less idiot-proof and have about the same power per unit volume as Lithium and power per unit weight between Lithium and Lead. We use them in our in systems and so does Toyota, Nissan and others in hybrid electric cars.

The comment about turbines is right on target. When will e able to buy the equivalent of a small Honda gas generator with a turbine (one moving part) instead of all the clap-trap junk of the Otto-cycle piston engine?
Hi there neighbor in Livermore, I'm just up the hill in Placerville and welcome to CF. If the diesel manufacturers would get off their profit laden butts and offer us something other than 70 year old heavy lumps of iron, I might not be pushing hybrid electric so much. There is no reason a very small displacement diesel can not be used, where it is turbo'ed and inter-cooled, produces 30 hp, but only weighs 200 lbs. As to the turbine, what is on the horizon for use as a range extender gen set for hybrid cars....
BladonJets Multi-fuel Micro Gas Turbine Engines
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Old 13-02-2012, 17:42   #87
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Re: Electrical Propulsion vs Diesel Propulsion

A gasturbine of a mere 350 kgs supplies some 2000 Hp; the smallest commercial gasturbine I saw was fitted on the tailpiece of an outboard and delivered 200 Hp.
Turbine Marine in Florida builds huge Off Shore racers using Apache Helicopter engines (Lycoming as I presume) in combination with Levi-drives getting in total 3400 Hp out of the twin configuration not bigger then V8 block. Problen is that the re-engineering and marinization of those powerplants is a costly affair.
However in combo with a large dynamo and an electric motor one may overcome the problem of the gasturdbine and that is the running on low revs is impractical.
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Old 13-02-2012, 17:51   #88
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Re: Electrical Propulsion vs Diesel Propulsion

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There is no reason a very small displacement diesel can not be used, where it is turbo'ed and inter-cooled, produces 30 hp, but only weighs 200 lbs. As to the turbine, what is on the horizon for use as a range extender gen set for hybrid cars....
[/url]
Small, lightweight , flexible.......seems perfect!!

http://www.steyr-motors.com/fileadmi...linder_web.pdf

I'm actually excited to see one of these!!
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Old 13-02-2012, 17:53   #89
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Re: Electrical Propulsion vs Diesel Propulsion

Here is a great blog post on the "battery problem". Turns out lead is pretty abundant and nickel and lithium are pretty rare. There isn't enough mineable nickel in the world to rely on NMH batteries as a mass market solution for cars or homes. Luckily recreational boating is not a mass market so we can use whatever we want for now.
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Old 13-02-2012, 17:53   #90
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Re: Electrical Propulsion vs Diesel Propulsion

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Can't agree entirely. We quite often sail anchor to anchor, or more often only use the motors for anchoring (up and down)..

But there's no denying that we also sometimes motor sail all day. Sometimes there are deadlines nature imposes - getting across a barred enterance while the tide is right, for instance.

For day sailors batteries and electric might work pretty well, but IMO for cruising you need either a genset to go with that or conventional motor(s).
I have to diesel half a day before I reach open water. Passing 7 bridges and two locks and again on the way back. Not all CFers are living in tropical/sub-tropical climates where you can sail from hook to hook.
In the Med too, there are many days w/o wind and some with too much wind. Dieseling down there is also not uncommon practice if you like to go places.

In the old logbooks of the VOC you may find data describing the days and days forced waiting for a bit of wind from the right corner.
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