Viability of electric only propulsion in 2018 - is there a good option after all?

[StuM]

Originally Posted by Paul Elliott

Can you post a link to that piece of wood spinning and climbing up the stream of water? I would really like to review that.

I think this may be it


https://www.reddit.com/r/interesting...tick_in_water/

[Paul Elliott]

Originally Posted by billknny

Paul,

I know you are smart enough to know you should never wrestle with a pig in the mud. He enjoys it and you just get dirty.

But I enjoy it too. It's interesting whether he believes it or if he's playing with us.

That spinning stick is cool though, even if I don't buy it. Searching for it, I found magnetically-powered microspinners used in medicine, but a plain wooden rotor like that isn't going to climb up a stream of water there's some serious cross-sectional speed-difference in the stream (and if it is real, that's why). Even then I don't understand it, but there needs to be some interface before mechanical energy can be harvested and used to counteract gravity and friction. And there's a lot of friction between the stick and the water stream.

https://zodab.com/interesting/carved-stick-in-water

[Dockhead]

Originally Posted by billknny

Paul,

I know you are smart enough to know you should never wrestle with a pig in the mud. He enjoys it and you just get dirty.

This is unkind, I think.


Didn't you ever, at least in your childhood, dream about perpetual motion machines? I did -- I drew hundreds of them. It's an attractive idea!




To the OP:


The problem with this idea is that you can't get something from nothing, where energy is concerned.


You don't have to be an engineer to understand the Laws of Thermodynamics (I'm not an engineer either), and you don't need to find an engineer to explain them:

• • The first law, also known as Law of Conservation of Energy, states that energy cannot be created or destroyed in an isolated system.
  • The second law of thermodynamics states that the entropy of any isolated system always increases.
  • The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero.

https://courses.lumenlearning.com/in...hermodynamics/


"Entropy" is the tendency of more organized systems to become less organized over time. It means in plain language that "stuff runs down" -- energy dissipates.



So what that means in total is that machines can't produce more energy than you put into them. No machine is 100% efficient, much less more than 100%.


So when you design a propulsion system, the goal is to avoid wasting energy to inefficiencies as much as possible. But forget about conjuring any energy out of nothing -- it really can't happen. Really.



I'm sorry if that's discouraging, but don't be discouraged -- it's fun to think about these things and try to imagine new ways to do stuff. You learn stuff even from dead ends, maybe even more!

[SailRedemption]

I thought the first law of conservation of energy was to never talk about the law of conservation of energy...?

Regards,
T. Durden

[Dockhead]

Originally Posted by SailRedemption

I thought the first law of conservation of energy was to never talk about the law of conservation of energy...?

Regards,
T. Durden

Would certainly conserve energy!

[john61ct]

Good piece on quantum weirdness https://www.quantamagazine.org/famou...ness-20181011/

[skipmac]

Originally Posted by StuM

I think this may be it


https://www.reddit.com/r/interesting...tick_in_water/

This link didn't work for me but Ms Google found a video of this. Not sure if it was the same video but the stick did not climb the stream of water. The stream of water flowing over the stick caused it to rotate vertically as some of the kinetic energy of the stream was transferred to the stick, then the water container was lifted up and the stick was held in the stream at roughly the same position.

Neat trick but no energy generated there, just a transfer but of course you know that.

[Paul Elliott]

Originally Posted by skipmac

This link didn't work for me but Ms Google found a video of this. Not sure if it was the same video but the stick did not climb the stream of water. The stream of water flowing over the stick caused it to rotate vertically as some of the kinetic energy of the stream was transferred to the stick, then the water container was lifted up and the stick was held in the stream at roughly the same position.

Neat trick but no energy generated there, just a transfer but of course you know that.

The buoyancy of the stick would also to some extent offset the force of gravity and frictional losses.

[skipmac]

Originally Posted by Paul Elliott

The buoyancy of the stick would also to some extent offset the force of gravity and frictional losses.

Probably so. Didn't consider that but off the top of my head I would guess that would be a very minor contribution.

[john61ct]

Originally Posted by Dockhead

I don't think it's a different dimension at all. Quantum physics have always been all around us

Graduate Student Solves Quantum Verification Problem

https://www.quantamagazine.org/graduate-student-solves-quantum-verification-problem-20181008/

https://www.quantamagazine.org/graduate-student-solves-quantum-verification-problem-20181008/

https://arxiv.org/abs/1804.01082

[liquidice]

Originally Posted by misfits

I wouldn't say less weight because FLA batteries are heavy but I agree with some of the other points. I have an electric drive & like it but it's not without it's shortcomings. Many that go electric tie up to slip & plug in. I'm on a mooring so I charge the battery bank with my solar system or a Honda generator which although it's quiet, I hate running it.

I can get 8-12 NM before hitting 50% DOD. For most of what I do that is adequate & meets my needs, cause after all it's a sailboat. Motorsailing with electric when you need a little boost is awesome. You can pick up anywhere between 1-2 knots, the motor is quiet & electric consumption is minimal.

However in my attempt to get the boat to it's winter home this year I ended up motor sailing against a tide with very little wind thanks to an inaccurate forecast from windy.com. I attempted a 22 mile haul & a mile from the yard after trying to tack & motorsail in the river for 5 hours I asked a fellow boater to tow me in. I made it 21 miles that day but my battery bank was depleted & there was no go go juice left in them.

My point is if you like motoring long distances or shoveling **** against a tide, electric probably isn't for you.

I love this thread because it is the most civil discourse I’ve seen since coming aboard the forum a couple years ago. This post is emblematic of that frank, real flavor to the point that I feel compelled to contribute. I have a small, light boat, Catalina capri 25, and I have a tertiary propulsion system configuration using 2x electric minnkota trolling motors with a dedicated deep cycle battery for each. I used it during light air days, on the outboard bracket, spread 3’ apart on a custom motor mount that I attach to the standard outboard mount. Coming on and off the mooring and as a booster to sail power it’s great. In a current, chop, or headwind, no go. Positive control is lost and sailing/boating becomes very stressful in a harbor/breakwater/traffic situation. With my current 6hp Suzuki dt6 long shaft, everything’s copacetic, and I haven’t been underpowered since. I still like to deploy the electric system for fun and principal, but it remains in 3rd place.

Could an outboard mod setup work to push your vessel that last mile? Especially in conjunction with your electric system, I could envision the inexorable forward thrust of a small OB being just the thing. Nobody likes that tow boat feeling. Maybe it’s worth supplementing your system somehow, preserving the electric system and adding some sort of detachable outboard motor and mount. Just an idea thanks for posting.

[KTP]

We are getting close to our first sea trial with our PS34 conversion to electric. We removed the engine, transmission, fuel tank, exhaust riser, hoses, sea water strainer, fuel filters. Oh it was a joy then to actually gain access to the rudder quadrant and rudder shaft stuffing box which I repacked (replaced the quadrant with a new one because old one cracked trying to get out the stainless steel into aluminum bolts). Even with the mounted electric motor it is still easy access and a complete joy compared to my attempts to squeeze past the 3HM35F with all of it's ancillary equipment.

Currently have a pretty small bank consisting of eight Lifeline GPL31-XT 125AH 12V batteries, four under the starboard couch and four under the port couch. I removed the four wet cell batteries in the aft port outside locker that were formally the house batteries and now use a 50 amp DC-DC to convert the 48V to 12V for things that need it. We use a Magnum 48V input inverter/charger to give us 4kW AC power from the battery bank and charge it with 60amps when connected to shore power. Gigavac 300 amp switches and fuses everywhere.

We plan on a second battery bank (actually the port and starboard Lifelines are organized into two switched and fused banks but we would normally not run them separately because of Mr. Peukert and his pesky law.). We might go with a bunch of lithium for the second bank, maybe in the aft port locker where the four house batteries used to be or perhaps even in the bilge where the fuel tank was if they fit. Those new Trojan LFP batteries coming out next year are supposed to be IP67 rated...

Before deciding on how big to make the second bank we want to do some testing within a few miles of our marina in various wind and water conditions.

[misfits]

Originally Posted by liquidice

I love this thread because it is the most civil discourse I’ve seen since coming aboard the forum a couple years ago. This post is emblematic of that frank, real flavor to the point that I feel compelled to contribute. I have a small, light boat, Catalina capri 25, and I have a tertiary propulsion system configuration using 2x electric minnkota trolling motors with a dedicated deep cycle battery for each. I used it during light air days, on the outboard bracket, spread 3’ apart on a custom motor mount that I attach to the standard outboard mount. Coming on and off the mooring and as a booster to sail power it’s great. In a current, chop, or headwind, no go. Positive control is lost and sailing/boating becomes very stressful in a harbor/breakwater/traffic situation. With my current 6hp Suzuki dt6 long shaft, everything’s copacetic, and I haven’t been underpowered since. I still like to deploy the electric system for fun and principal, but it remains in 3rd place.

Could an outboard mod setup work to push your vessel that last mile? Especially in conjunction with your electric system, I could envision the inexorable forward thrust of a small OB being just the thing. Nobody likes that tow boat feeling. Maybe it’s worth supplementing your system somehow, preserving the electric system and adding some sort of detachable outboard motor and mount. Just an idea thanks for posting.

Thank you for the kind words.
Regarding an outboard setup, it would be possible. Currently I have a 2 stroke, 2 HP motor on the dingy. I've had this motor for the better part of 30 years. Sooner or later it will die & when it does I'll probably put a 4-6 HP motor on the dingy. The issue I'll have is dealing with the extra weight of a 4 stroke & handling it up to the stern rail when I tow the dingy. One of the things I've considered for that situation would be a outboard motor bracket to store the motor. I could move the engine from the dingy to the bracket at water level, then pull the bracket up & store it that way on the transom.
This approach would give one a lifeline so to speak.

All in all, I was pleased with how far I did push the electric drive & battery bank that day.
My biggest mistake that day was trying to stick to a schedule....

[Augi]

Originally Posted by misfits

Thank you for the kind words.
Regarding an outboard setup, it would be possible. Currently I have a 2 stroke, 2 HP motor on the dingy. I've had this motor for the better part of 30 years. Sooner or later it will die & when it does I'll probably put a 4-6 HP motor on the dingy. The issue I'll have is dealing with the extra weight of a 4 stroke & handling it up to the stern rail when I tow the dingy. One of the things I've considered for that situation would be a outboard motor bracket to store the motor. I could move the engine from the dingy to the bracket at water level, then pull the bracket up & store it that way on the transom.
This approach would give one a lifeline so to speak.

All in all, I was pleased with how far I did push the electric drive & battery bank that day.
My biggest mistake that day was trying to stick to a schedule....

Can anyone explain why Volvo or Yanmar or some one similar is not offering parallel diesel / electric hybrid where the electric motor and diesel engine can turn the same direct drive, drive shaft for cruising boats of 50 ft and less?

Steyr Motors(see link below), offers the above type solution but the smallest diesel they offer the hybrid solution with is 59 KW, to big for 50 ft and less.

The STEYR HDS - Hybrid Drive System - Steyr Motors

For long range cruising until battery technology gets a lot better it seems the most viable way to incorporate as much electrical propulsion as possible is with a hybrid system as described above and at the link above.

A lot of cruising boats already have a diesel engine and generator on board. So the above does not require anymore equipment or more weight than many cruising boats already have. All that is required is the engineering to do it. If well engineered it would be simpler than a separate diesel engine and separate generator.

With the above you could always go with electric propulsion until the batteries ran down, and then switch to diesel unless you needed more power. The motor could then become a generator(driven by the diesel), and charge that batteries.

With the Steyr solution at the link above both the diesel engine and electric motor can be used to propel the boat at the same time to get the extra power.

With the different power and torque curves of diesel and electric it seems like a win to have both available. There must be technical reasons I am not aware of that get in the way and / or drive the cost or weight up.

[Jon Hacking]

Augi, that's a cute system. The answer to "Why don't they ..." is almost always: money. I hope Steyr can make money out of this, but I hadn't heard of them before you mentioned them. Yanmar DID have a charging system that slipped between the engine & gearbox & had a pair of 3KW coils that fed an inverter type box on the wall that turned the variable AC output into regulated 230vAC. But it didn't sell, so I think they've dropped it.

To say the Steyr system doesn't add weight is a bit misleading. If you already have a gen-set, then OK, but you'd still need a whack of batteries to power the motor/generator for long. You'd also run up the hours on your drive diesel using it for both drive & charging, & most diesels don't really like being lightly loaded (7KW on a 55+KW engine). Still, that's more load than a normal alternator would give, & with Lithium batteries, charging times would be reduced. And 55KW is only 75HP, so not unreasonable for a 50' sailboat. An interesting system.