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  #11  
Old 04-26-2008
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trolling motors

Another short term option for using electric propulsion is a removable trolling motor. It will not push your boat very fast, but is possible to dock, anchor, tour close to shore and motor sail effectively with no noise and not having to warm up the diesel. It is not possible as the only propulsion source, but can be a great add-on. The new Torqeedo 2.0 looks sufficient for our 33' boats for that purpose.

We used a pair of EM54 Minn Kota trolling motors one season on our Pearson 33 day sail charter boat. These trolling motors on brackets wore out because they are not meant to be towed or left in the water. We did use it for 1-4 hours per day for about 70 days. With both of them on, we could go about 2.5-3 kts. It was a 24v system and would run at about 30 amps, if I remember right. On two 3 hours sails with almost no wind, we used about 200 amp hours on the heaviest days. There were weeks doing twice-per day trips that the diesel was not used at all. Our docking situation is simple, so that helped. The best part was that you can just flip a switch for instant power. We were able to sail into situations that most people would use the motor and have the instant boost of power if the wind failed us. A little boost on light wind days to get to another puff of wind, or just to get some air moving over the sails really cut down on diesel motoring.

Experimenting with electric drives is fun and will drive technology. What we need is an electric motor that works on the current drivetrain when needed. Briggs & Stratton made a brushless motor (Etec?) that was about 8 hp, worked in both directions, charging and driving, and was for golf carts.
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Medsailor...

You have got this wrong.

By "diesel electric" you are referring to a power system that has a generator, an electrical power line, and a remote motor. The reason why they do this is to avoid the mechanical engineering involved in coupling a big motor to a big prop. Also, the generator serves a power for the ship also, BUT IT IS RUNNING ALL THE TIME!!!! Diesel electric trains do it too, and for reasons of coupling also, particularly with multiple drive wheels on the loco.

What they are referring to is... and I quote...

"Picture yourself in pristine lagoons and allow the power of the sun, tides and wind to replenish your cruising. Motor away from distant fuel docks of unknown diesel quality without bating an eye. Remove your portion from our oil burden while silently cruising into distant harbors. Live the Solidnav shift, change your world. "

This is charging a battery, then running constant loss on the battery, and no-doubt having to compete with the sort of energy delivery I calculated.
Is that what you mean by "diesel electric"? ...because that is not what ships have and not what trains have.

Where does the energy I describe come from?... does anyone plan to store even a fraction of that in a battery bank???. How far would you get before you have to start the diesel to drive the prop. When you do, you would be much better to save energy a-plenty by joining the prop to the motor by a shaft and dump the generator, cabling, and motor.

There is just not enough energy stored in the battery bank, this side of sanity.

For a submarine submerged it can work for a while... another type of "diesel-electric"... but have you ever seen the battery bank on one of those beasts?
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Quote:
Originally Posted by Rockter View Post

What they are referring to is... and I quote...

"Picture yourself in pristine lagoons and allow the power of the sun, tides and wind to replenish your cruising. Motor away from distant fuel docks of unknown diesel quality without bating an eye. Remove your portion from our oil burden while silently cruising into distant harbors. Live the Solidnav shift, change your world. "

This is charging a battery, then running constant loss on the battery, and no-doubt having to compete with the sort of energy delivery I calculated.


Where does the energy I describe come from?...

There is just not enough energy stored in the battery bank, this side of sanity.
You do not yet understand how these systems work. They do not need the batteries to see the reduced fuel costs and the use of batteries can remove the need for diesel.

The Solidnav system recommends using windmill generator, solar, tow drogue generator, and regenerative power under sail, to achieve the "Solidnav Shift" with no diesel. If you are sailing away from the diesel pumps you can be charging the batteries. That would be the same battery bank you could use to run other, or all, electrical items on the boat.

This "Regenerative power" is produced whenever the system is on, and the boat is under sail, moving fast enough to cause the propeller to rotate. This rotation causes the electric motor to act as a generator. You can adjust how much charging occurs once you are above the minimum speed required to generate.

This means that if winds are light you might discharge the bank to add to the sailboats speed and then recharge later when the wind picks up. It would be a different way of sailing which I expect would take some getting used to.

And the assumptions you used for your calculations are incorrect which is why your calculations and understanding appear insane. A little more research should have you seeing why these drive systems are so much more efficient. Maybe start here: solidnav.com/faqs.htm

Last edited by Architeuthis; 04-26-2008 at 05:40 PM.
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I'm with Rock on this one BUT...things are getting interesting with the new battery technology and I can imagine a day in the not too distant filter where a diesel gen and electric motor, with an advanced battery bank may be the preferred way to build a boat and go to sea.
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Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice
I think you "Einsteins" need to read more...

READ HERE to start...
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Quote:
Originally Posted by Giulietta View Post
I think you "Einsteins" need to read more...
Good link but we don't all figure things out the first time. I seem to recall it took Einstein a while to get his head around the need for ether.
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Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice
Look...this is what I do for a living...so in reality...writting in this thread would be working for me...and I only work if I get paid....sorry

So that was my contribution here...signing off.

In the mean time...I find some posts really amuzing.
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Arch... what you are saying is TOTALLY impractical on a cruising sailboat. This is so ridiculous I can't even begin to refute it. Tell ya what...as soon as someone crosses the Atlantic or Pacific with their cruising electric motor sailboat and NO diesel...let me know. The FAQ's you reference are a complete joke and lack any substantive information. This is presently smoke and mirrors.
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power density of combustible fuels is orders of magnitude higher than that of electric batteries we have today. until fuel cells arrive - all this electric stuff is a total bs. look, on one hand everyone runs around wondering how to reduce electric use so that running a tiny pathetic refrigerator for a day does not kill batteries. and yet someone can seriously propose pushing the entire boat with this? This is just ridiculous, no other words for it.
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Quote:
Originally Posted by camaraderie View Post
Arch... what you are saying is TOTALLY impractical on a cruising sailboat. This is so ridiculous I can't even begin to refute it. Tell ya what...as soon as someone crosses the Atlantic or Pacific with their cruising electric motor sailboat and NO diesel...let me know. The FAQ's you reference are a complete joke and lack any substantive information. This is presently smoke and mirrors.
This is really very old news, there isn't anything new being posted or suggested.

Electric motor sailboats have been around since, well, since before diesel engine sailboats. This technology using Pulse Width Modulation is more efficient but has still been around a long time.

And yes people have crossed oceans with this type of drive system. Solomon technologies has been around for years: The longest-distance STI customer we know of - a retired Los Angeles physician - has been at sea for years with a battery-bank-only system and no backup generator. He has successfully sailed the Pacific to Tahiti.

This technology has been used in electric cars for years. They do not get the same regen effect because they cannot get motive power from the wind. If they were to only drive down hill I guess it would be similar.

As for the idea that it is better to have a diesel motor run a generator which then runs an electric motor for power, that is well over 50yrs old and is in common use every day.

I'm not sure why people are not aware of this. It hasn't been a secret. The only problem has been the extra cost of the installation. Like insulating your house it can be hard for some people to understand why it is a good idea but once you look you will notice that lots of people insulate and lots of people (not as many) use electric drives.
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