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Old 05-06-2016, 07:30   #16
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Re: Electric Conversion

I am only talking about an electric motor which performs much like an electric powered pump. I may be wrong but I am using the information taught to me in Naval Nuclear Power School and operator experience on a nuclear submarine from loss of reactor power training when we are only operating on the battery.

When we are on the battery we have to rig for reduced electrical. One of the things we are taught is that three of the same pumps in slow are more efficient (electric power consumption) than one of the same pumps in fast. This is based on the pump laws that I quoted and I have seen it work in real time sitting at the electric plant control panel...because I am an electricians mate.

I was also the battery petty officer so I have also become very intimate with battery sciences, maintainence, and operation.

The saltwater battery is not fringe science. The electrons are free from the water just like they are in a child's science project lemon or potato battery. The metal lost in galvanic corrosion is not.

As long as you have two different metals in an electrolytic solution...it's a battery. And you can make 12 reliable dc volts in the same volume as a car battery.

I may be new to this forum and im not trying to step on any bodys toes but this has been my actual job for a couple months short of a decade.
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Old 05-06-2016, 07:37   #17
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Re: Electric Conversion

Pb(metal)+PbO(a different metal)+H2SO4(electrolyte)<charge/discharge>PbSO4(salt)+H2O(water)+e-(pixies)

Charge/discharge equation for an actual lead acid battery. They all work the same. I promise you.
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Old 05-06-2016, 07:59   #18
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Re: Electric Conversion

I have been doing weeks of research (forums for electric cars, websites, youtube,research on solar, motors, small power distribution and handling, LED lighting, sailing in danger us conditions... and the counsel of nerds at work).

Electric motor are not measured in power the same as engines. It's very cryptic and there is a lot of over estimation by manufactures. It's almost impossible to get real data from numbers except from those who have actually done it. Because naysayers for some reason go against any effort to try new ideas and discourage people from challenging convention knowledge...like only birds can fly.

The selling point for electric trolling motors was multiple videos on youtube of real people with real substantially sized sailboats boats getting 2.5 knots from one 55lb thrust trolling motor.

I can move my boat with one motor...when i need to. And when I need to I will drop it in the water. Because I understand drag on the cone shaped tip of a trolling motor is such a tremendous drag that my boat might possibly stop in plague as if I threw out a sea anchor and I wouldn't want to do that when I am trying to push myself with wind.

If for some reason I need more power than that...I will drop a second sea anchor motor in the water and use it to get the one extra knot to overcome the extreme drag.

I figure if I huff and puff with my lungs and blow a small dc powered ventilation fan in my sails as well that the extra added force on the mast will overcome the drag of the second motor.
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Old 05-06-2016, 08:20   #19
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Re: Electric Conversion

These folks made an all electric cruising sailboat. They post in their videos and web page lots of detail of how they did it. https://www.youtube.com/channel/UCXb...nNJPVlg/videos
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Old 05-06-2016, 09:47   #20
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Re: Electric Conversion

Quote:
Originally Posted by HillbillyMatt View Post
I am only talking about an electric motor which performs much like an electric powered pump. I may be wrong but I am using the information taught to me in Naval Nuclear Power School and operator experience on a nuclear submarine from loss of reactor power training when we are only operating on the battery.

When we are on the battery we have to rig for reduced electrical. One of the things we are taught is that three of the same pumps in slow are more efficient (electric power consumption) than one of the same pumps in fast. This is based on the pump laws that I quoted and I have seen it work in real time sitting at the electric plant control panel...because I am an electricians mate.

I was also the battery petty officer so I have also become very intimate with battery sciences, maintainence, and operation.

The saltwater battery is not fringe science. The electrons are free from the water just like they are in a child's science project lemon or potato battery. The metal lost in galvanic corrosion is not.

As long as you have two different metals in an electrolytic solution...it's a battery. And you can make 12 reliable dc volts in the same volume as a car battery.

I may be new to this forum and im not trying to step on any bodys toes but this has been my actual job for a couple months short of a decade.
You are taking two different issues and trying to equate them. Part of the issue is you are using shorthand rather than proper units (electric motors and ICE are easily equated if you convert both to KW at known RPM ranges. Don't let someone tell you the falsie that electric HP is more powerful than diesel HP on a cruising boat at cruise speed)

In pumps, drag increases as the cube of flow rate.
- One pump putting out 100gal/min will take more power than two (of the same size and type) pumps each putting out 50gal/min assuming they are operating on independent circuits.

The problem with trying to apply this to a pair of trolling motors is you aren't talking about flow in a restricted pipe. That drag which kills the efficiency of a pump, is actually creating the thrust for the boat. More drag the more thrust.

If you think of it like a wood screw, in a perfect world, one rotation of the propeller would advance the boat a distance equal to the pitch of the propeller (lets say 11"). In reality, there is always some slippage. At very low speeds, that slippage tends to be high. As you increase power, the slippage is reduced. For displacement boats, there is a final stage where you reach hull speed and slippage increases but you won't be anywhere close to that range with trolling motors.
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Old 05-06-2016, 10:42   #21
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Re: Electric Conversion

Valhalla got there first.

Pumps are not propulsion motors. It's why you used multiple pumps, but the sub only had one prop. If multiple props were more efficient they would just swing a lot of small props out the back of the sub.

I am one of the people who converted a sailboat to use a trolling motor. It works fine, within the limitations of the system. In my case it was a 30' 3,600lbs sailboat with a 55lb MinnKota. The boat would hit about 2.7kn in dead still water and no breeze. Motoring into a 10kn headwind but with no waves we could hit about 1.5kn.

This was fine to get us in and out of the marine, but that's about all.
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Old 05-06-2016, 11:15   #22
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Re: Electric Conversion

Now those replies are helpful. Thank you.

I'm not afraid to admit incorrectitudeness when I'm wrong or stupidity when I mess something up, but Naysaying is against my lifestyle and I can't stand it. It holds back hummanity from achieving by destroying our will to learn and do new and better things. It is always broken and we can always fix it.

If you want to tell me a personal sea story about a factual event that happened to you I will listen and learn.

I want to know how I CAN do this. Please don't lecture me how you personally think I will fail or scoff at my pursuing ideal and attitude.

I want a 100% clean, safe, and self sufficient sailboat that is easy to use, innexpensive to operate, and reliable.

I want it to be better than a petroleum chugger.

And most importantly I want to show hummanity that it DOES work and ANYBODY can do it.

I am an IDIOT and I WILL achieve my goals.
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Old 05-06-2016, 11:31   #23
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Re: Electric Conversion

It absolutely is possible. I thought I mentioned this before but I guess not. Go read Mbianka's blog about switching a nunsuch 30 to all electric (with a gas gen range extended). it isn't hard to do, or technically impossible. It just comes with real tradeoffs on range and speed.

So long as you are willing to live with those trade offs it's fine. But there is a fundamental reality that diesel has about 50 times as much usable energy per pound as the best lifepo batteries do. So you have to accept a far shorter range than a fossil fueled boat would have.

The trolling motor thing..l that's just details around the edge. They aren't designed for what you want them to do, and really aren't the best option. A small electric outboard, or a shaft drive to a prop is a far better option.
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Old 05-06-2016, 11:47   #24
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Re: Electric Conversion

Quote:
Originally Posted by Stumble View Post
Valhalla got there first.

Pumps are not propulsion motors. It's why you used multiple pumps, but the sub only had one prop. If multiple props were more efficient they would just swing a lot of small props out the back of the sub.

I am one of the people who converted a sailboat to use a trolling motor. It works fine, within the limitations of the system. In my case it was a 30' 3,600lbs sailboat with a 55lb MinnKota. The boat would hit about 2.7kn in dead still water and no breeze. Motoring into a 10kn headwind but with no waves we could hit about 1.5kn.

This was fine to get us in and out of the marine, but that's about all.
I can't talk about why we only use one giant hydrodynamically perfect screw with a certain number of blades because it's classified. But I can say a sailboat is not a submarine that relies on slow silence with an astronomical budget for propulsion power.

Again again. I would only be using the second motor if I need it for extra push. I am not worried about long term battery depletion and I don't mind going slow. I just don't want to be in a narrow channel with head wind and current when I find out my one trolling motor is maxed out.

With two of them I should never be dead in the water or pushed outside the channel markers. With two motors I should always be able to safe execute a trailer extraction. With two motors I will always have a spare.

With the numbers i am collecting there is no reason they couldn't out perform a 5 to 10hp gas outboard. That said, time and EXPERIENCE will tell.

I would like to know if anyone has real results while using two trolling motors at once. If I can achieve a marked difference in speed and thrust I'll plan my battery and solar system to handle it.

It's not that big of a deal how many motors I'm using and when I'm using them. They will rarely be used and rarely in contact with the water because I like and know how to sail.
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Old 05-06-2016, 11:58   #25
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Re: Electric Conversion

Has anybody actually used two trolling motors or multiple electric motors at one time to push a sizable boat so we can put this to rest? What were the actual numbers? (knots, voltage, head winds, currents, battery discharge, capacity of battrey)

How did you feel about it? Are you sold? If you didn't like it...WHY? Real facts based on actual events that occurred pros and cons?

If nobody has done it I guess I will have to and let you know what happens. Either way I am buying and keeping two on board in case one breaks. it's only $400 total and free clean power from Jesus.

I'm going to build my own solar panels for christ sake. I have a garage full of tools and a healthy budget set aside to build this boat. I'm not too worried about the price.
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Old 05-06-2016, 12:05   #26
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Re: Electric Conversion

If you haven't tried two motors, can you borrow another one, duct tape it on your rudder and see what happens? Lol.

Make a video or just tell me the truth, I'll believe you...possibly. make a video.

I can tell you that you would be the first @$$hole on youtube to do it.
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Old 05-06-2016, 12:15   #27
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Re: Electric Conversion

4kw electric outboard pushing 10 ton sailboat in 3,5 knots.

http://youtu.be/2rL1-b-E_Ho
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Old 05-06-2016, 12:25   #28
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Re: Electric Conversion

Quote:
Originally Posted by Stumble View Post
It absolutely is possible. I thought I mentioned this before but I guess not. Go read Mbianka's blog about switching a nunsuch 30 to all electric (with a gas gen range extended). it isn't hard to do, or technically impossible. It just comes with real tradeoffs on range and speed.

So long as you are willing to live with those trade offs it's fine. But there is a fundamental reality that diesel has about 50 times as much usable energy per pound as the best lifepo batteries do. So you have to accept a far shorter range than a fossil fueled boat would have.

The trolling motor thing..l that's just details around the edge. They aren't designed for what you want them to do, and really aren't the best option. A small electric outboard, or a shaft drive to a prop is a far better option.
I have noted the obvious design flaws of trolling motors for this application and thought hard about doing a motor conversion. In the end I came to the conclusion that it would be much more of a pain and way more expensive with questionable reliabillity.

I settled on the trolling motors being cheap, proven to push water, readily available as far as parts and replacements, and they do have small upgradable props. So small that I can easily fabricate one with marked improvements in efficiency on a 3D printer...possibly even a shrouded propulsor attachment or prop.

The one benifit of the electric motor that I could capitalize on is the plateau torque curve characteristics. They will most definately push water through a shrouded propulsor at any speed. As soon as the motor is turned on all of the torque is available. They do this all the time on vessels like the NR-1 and the Alvin and countless ROVs.

I am amassed that no one has come up with a marketable electric motor propulsor design for trolling motors because exactly what I'm talking about used on every single submarine in our navy as a backup surfaced means of propulsion. We drop one out of the ballast tank and use it to help with unassisted moorings and waterborne personnel transfers.

The whole unit, motor and propulsor, is the size of a house side trashcan...it's a huge trolling motor...with a propulsor.
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Old 05-06-2016, 12:29   #29
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Re: Electric Conversion

Quote:
Originally Posted by offpist View Post
4kw electric outboard pushing 10 ton sailboat in 3,5 knots.

http://youtu.be/2rL1-b-E_Ho
They cost four times as much as I paid for my boat and thats jus the motor. Lol. I would if I had it like that but the price has to come down quite a bit. I'm looking to do my entire electric boat conversion for around the same price and from what I'm learning it's totally doable.

And I would almost say that torqueedo makes fraudulent claims about their products. Their products are not marine grade, can put people in potentially deadly situations, and they charge astonomical amounts of money to do so. I was considering coughing it up to get a proffessionally made torqueedo until I read the reviews that they last about a week before they leave you stranded.
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Old 05-06-2016, 12:41   #30
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Re: Electric Conversion

$400 2xtrolling motors
$450 set of golf cart batteries
$750 power converter
$500 (over estimate) DIY solar panels
$400 distribution system
$100 LED lighting
$2600total》say $3000 to be safe

That's the whole package to be safe and seaworthy.
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