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Old 11-18-2018, 06:41 AM
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Originally Posted by fishmonger3 View Post
[b]

Rube Goldberg, not really. Basically that's exactly how Diesel Locomotives work.

https://science.howstuffworks.com/tr...locomotive.htm
Of course it is. Why? STARTING. Those traction motors allow the the train to start smoothly from ZERO rpm. They also have regenerative braking, but that heat is wasted to the air. Many ships use turbines to produce power and run generators to run motors to run the props. Cheaper and more effective than complicated mechanical gear reduction.

Keep trying. Form follows function.
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Old 11-18-2018, 07:04 AM
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Originally Posted by fishmonger3 View Post
[b]

Rube Goldberg, not really. Basically that's exactly how Diesel Locomotives work.

https://science.howstuffworks.com/tr...locomotive.htm
There are a number of ships that were built with diesel-electric motivation. WWII subs would be a good place to start, and they even included batteries!

Many of the old lightships were built the same way. Some current vessels with pod drive are too, because you can put the whole motor in the pod and make it direct drive to the prop and don't have to worry about gears.
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Old 11-18-2018, 07:06 AM
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If sailboats were really smart, they'd start using lead-acid keels.

Imagine what an 8,000 or 12,000 lb battery would give them in capacity!
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Old 11-18-2018, 07:54 AM
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Originally Posted by km1125 View Post
If sailboats were really smart, they'd start using lead-acid keels.

Imagine what an 8,000 or 12,000 lb battery would give them in capacity!
Anything but lithium.

Running over a submerged object and holing a battery would make for quite an explosion.
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Old 11-18-2018, 08:12 AM
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I saw a 44ft Lagoon sail Cat with twin electric motors powered by a 12kw gen. Of course they were inboard. It had a decent sized bank of batterys. Owner claimed 2gph on gen.
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Old 11-18-2018, 09:45 AM
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Originally Posted by Knight View Post
I saw a 44ft Lagoon sail Cat with twin electric motors powered by a 12kw gen. Of course they were inboard. It had a decent sized bank of batterys. Owner claimed 2gph on gen.
would that be +/- 7kts = 3.5 kmpg? diesel/electric has proven to work well elsewhere. however, i feel like the bulk of boat-folk here like to go really fast. go-fast electric boats are likely quite a ways off....until a battery breakthrough happens. but may be close for displacement applications.
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Old 11-19-2018, 05:23 AM
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The electric motor stuff is out of my league. However I would like you all to think about this. The Staten Island Ferry is powered by electrical motors, (inboard) which receive there electricity from diesel generators, my buddy works on there propulsion systems. Now I don't know how fast they go, (they are big and always on plane) but I would guess 20-30 mph. So if this is the way the ferry authority chooses to go why is not a reasonable alternative? I would think if it was not a reasonable choice they would have discontinued it.
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Old 11-19-2018, 06:02 AM
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Originally Posted by Clamdigger II View Post
The electric motor stuff is out of my league. However I would like you all to think about this. The Staten Island Ferry is powered by electrical motors, (inboard) which receive there electricity from diesel generators, my buddy works on there propulsion systems. Now I don't know how fast they go, (they are big and always on plane) but I would guess 20-30 mph. So if this is the way the ferry authority chooses to go why is not a reasonable alternative? I would think if it was not a reasonable choice they would have discontinued it.
They do this for maneuverability. Easier to change direction quickly. The may even use an azipod set-up.

It has NOTHING to do with efficiency.
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Old 11-19-2018, 07:28 AM
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Every output needs an input. Building an electrically powered propeller turner is a relatively trivial engineering task. Building a practical power supply to deliver the electrical power required by the propeller turner is a holy grail that, as yet, has defied the best minds on the planet. There are no free lunches when it comes to energy and losses aplenty. This propeller turner is limited by distance, time and recharge source - not to mention the risk of the usual sea-going SHTF scenarios.

Remember - you can always hoist a sail for quiet, almost limitless power. There. I said it!!
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Old 11-19-2018, 11:14 AM
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Originally Posted by grodywhite View Post
Every output needs an input. Building an electrically powered propeller turner is a relatively trivial engineering task. Building a practical power supply to deliver the electrical power required by the propeller turner is a holy grail that, as yet, has defied the best minds on the planet. There are no free lunches when it comes to energy and losses aplenty. This propeller turner is limited by distance, time and recharge source - not to mention the risk of the usual sea-going SHTF scenarios.

Remember - you can always hoist a sail for quiet, almost limitless power. There. I said it!!
On Craigslist a while back, some dude converted a sailboat to electrical using a 3HP motor and an assload of lead acids. For 30k. All in an attempt to be zero emissions.

He could have just used the sail.
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Old 11-19-2018, 11:30 AM
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Being an impossible task for me to explain some boaters here that perpetual motion is something unachievable, and why converting the mechanical energy produced by a generator of any kind (diesel or gas) into electric energy has massive looses, which get even larger if you intend to accumulate that electric energy into batteries since charging is in itself very ineffective and unefficient ( because most of the energy is lost during the charging process) and since the US is a Christian country (still), I will resort to faith ............. please believe me when I say this: that engine and in fact any electric one to the purpose of powering a boat with any decent performance and autonomy is a BIG TURD ..... as some have said already due to the unavailability of a good enough battery technology with a good enough energy density that means a battery capable of storing an equivalent amount of energy of the energy a gas tank can store and with a similar weight, those batteries when and IF they ever get invented ( since scientists have been looking for them for several decades now to no avail) may never be invented and untill that breakthorough arrives remember my words any electric powering af any device that needs to be light to have a decent performance ( trains and slow displacement ships excluded ) is a very naive idea indeed or to be more precise a TURD IDEA .............. I am a master civil engineer and I know what I am saying ..... now call me whatever you want and run and buy one of those silent 450 hp marvels for your boat, but remember I warned you.
Jose from across the pond ...........
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Old 11-19-2018, 01:42 PM
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Originally Posted by 1NO REGRETS View Post
WHY WOULDN'T IT HAVE A TURBINE THAT IS IN THE WATER TO CHARGE THE BATTERIES AS THE BOAT IS IN MOTION? Or, maybe a wind/solar on the tee top or hardtop? or all three. it may even be recharged by water passing through the lower unit.
Possibly for the same reason that you can’t fly by pulling up really hard on your shoelaces.
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Old 11-19-2018, 02:08 PM
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Originally Posted by CANARIANFISHER View Post
due to the unavailability of a good enough battery technology with a good enough energy density that means a battery capable of storing an equivalent amount of energy of the energy a gas tank can store and with a similar weight, those batteries when and IF they ever get invented ( since scientists have been looking for them for several decades now to no avail) may never be invented .
Currently there is no battery good enough but I think the Goodenough Battery under development shows a lot of promise, I know a very unfortunate name. John Goodenough is the main inventor of the current Lithium Ion battery. His team is working on the next big thing in batteries and from the papers he is writing either he is getting delirious in his old age or he may be getting closer. Not close as in months it may be several years or decades, who knows but technology continues to develop. Think about the difference in battery tech today versus 20 years ago, if they continue that curve we or our children may see an offshore planing hull boat with an electric motor.

By the way, I don't think they actually call it the Goodenough battery, I just think his name is so ironic for his work that I call it that.
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Old 11-19-2018, 02:52 PM
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As has been said by people who know what they are talking about, you can't just stick a water driven propellor driving an alternator to make enough power to charge the battery required, a 40 acre farm covered in solar panels will not be enough either, the battery technology is getting close, however, charging is the killer, it takes either time, or mega supply power, and if you have the supply, it's not free, at the present time, that motor is just for boat shows and Internet forums, the perpetual motion brigade need a reality check.
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Old 11-19-2018, 03:09 PM
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Originally Posted by noelm View Post
As has been said by people who know what they are talking about, you can't just stick a water driven propellor driving an alternator to make enough power to charge the battery required, a 40 acre farm covered in solar panels will not be enough either, the battery technology is getting close, however, charging is the killer, it takes either time, or mega supply power, and if you have the supply, it's not free, at the present time, that motor is just for boat shows and Internet forums, the perpetual motion brigade need a reality check.
This.

Again, perpetual motion only works if you take NOTHING out.
Ex: An object spinning in zero G, vacuum; said object will spin indefinitely.

The moment you try and do work with that spinning object, such as weld on a shaft and turn a generator, it'll slow down and STOP.

The battery-motor-alternator-battery farce wouldn't work because of thermal inefficiency; not all the energy into the battery is converted into work, and back again.

Believing in perpetual motion machines is abject denial of science.


As for the battery tech, good luck filling a boat with 1500 pounds of metal that ignites on contact with water. I'll take a 6BT please.
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Last edited by Argon; 11-19-2018 at 03:18 PM.
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Old 11-19-2018, 04:05 PM
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A Mr Fusion home energy reactor puts out 1.21 giga watts in a small lightweight package. May need to make the hull from stainless steel for the correct flux dispersion though.
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Old 11-19-2018, 05:00 PM
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Originally Posted by km1125 View Post
There are a number of ships that were built with diesel-electric motivation. WWII subs would be a good place to start, and they even included batteries!

Many of the old lightships were built the same way. Some current vessels with pod drive are too, because you can put the whole motor in the pod and make it direct drive to the prop and don't have to worry about gears.
My dad was engineering officer on a ww2 destroyer. They used (whatever) to run a turbine to run a generator to run a motor to turn the prop. Too complicated to gear down a turbine to prop shaft speed.
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Old 11-19-2018, 05:18 PM
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Originally Posted by billinstuart View Post
My dad was engineering officer on a ww2 destroyer. They used (whatever) to run a turbine to run a generator to run a motor to turn the prop. Too complicated to gear down a turbine to prop shaft speed.
They used steam to turn a turbine, coupled to a generator, to drive motors.

This removed the need to precision grind the double reduction gears. Blame wartime shortages.

The downside of turboelectric is the peril of high voltage.
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Old 11-19-2018, 05:36 PM
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Nearly all modern cruise ships and container ships are diesel electric, it's nothing new, however, it's not done for better efficiency, it done for convenience, you can have the diesels mounted almost anywhere in the ship, and the electric azipods make steering and docking a breeze, diesel electric trains are made that way for torque low down, and the diesels can run at constant efficient speeds, no gearbox as such, reverse is easy too.
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Old 11-19-2018, 05:41 PM
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Originally Posted by noelm View Post
Nearly all modern cruise ships and container ships are diesel electric, it's nothing new, however, it's not done for better efficiency, it done for convenience, you can have the diesels mounted almost anywhere in the ship, and the electric azipods make steering and docking a breeze, diesel electric trains are made that way for torque low down, and the diesels can run at constant efficient speeds, no gearbox as such, reverse is easy too.
Cruise ships yes, CVs sometimes.

Most container vessels have slow speed direct coupled engines. It's the simplest drivetrain.
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