Diesel Electric Propulsion

[Cheechako]

I think it may be the future... hard to say. But the right system hasn't been developed and optimized yet. I mean.... it works great for the Toyota Prius right? There's no "in and out of the parking lot" with those... you can drive cross country if you want.
As mentioned... expense may be an issue. But if a well designed system were out there, that provided house battery charging as well etc.... maybe the true cost wouldn't be so high. Take the cost of a diesel, add the cost of solar panels and a hi output alternator and regulator etc etc. Is that still less than the hybrid system?
maybe weight is an issue with all the batteries?
I often wonder though.. what about hydraulic drive from a generator/pump? Isnt this similar but with a hydraulic motor instead of electric motor? The advantage of Hydraulic is you get rid of all those batteries...(weight and cost!) except the house batteries...?
Many things like Kubota 4WD tractors are all hydraulic now. I suppose you could buy a $12k Kubota tractor and strip all the stuff you need off it!

[a64pilot]

The Prius works largely because most driving is stop and go, you can regain energy used by regenerative braking with a hybrid where a non hybrid wastes that energy as heat.
Also the torque of th eelectric motors allow th euse of an Atkinson cycle power plant, which without the electric motors just couldn't accelerate the car
Atkinson cycle - Wikipedia, the free encyclopedia
Which is not to say that Hybrid boats won't work, but I bet if anything during periods of motoring, they will be less efficient than direct drive, not more so, so what will drive the adoption of a hybrid boat will not be decreased fuel use, or any saving of money as I'm sure it will be more, not less expensive. Hybrid cars if driven enough can mkae ecenomic sense, I doubt hybrid boats will.

[Cheechako]

Actually I've driven rented Prius' 100's of freeway miles with no issues at all.... very little braking involved.

[CaptNemoO2]

Originally Posted by Cheechako

Actually I've driven rented Prius' 100's of freeway miles with no issues at all.... very little braking involved.

You can drive a Prius all day at highway speeds, but at that point it is no more efficient than any other small car with a tiny engine. As a64pilot said, where they really shine is in stop and go traffic were they can regenerate a large portion of the electric energy by using the motor as a generator for braking. On the highway, cruising at a relatively steady speed you loose that advantage. And also as pointed out to me many times by several mechanic friends, people who drive Priusi on the highway or normal around town traffic find that they could be left with no real brakes. The real brakes get used so little that I have seen several that have frozen up. But when they work, they can last for a long time. I saw one that had 120K miles on the original brakes, and they weren't even half worn. If I get 25K miles, I consider myself lucky!

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[JayWit]

Ok this is my first post on this forum so sorry if it doesn't look pretty.

I have been looking into diesel electric marine propulsion for some time now. Currently larger ships have been using series diesel electric systems to supply power for propulsion and auxiliary power. The reasons for this are many and differ depending on the application. However, the main reasons are typically due to the efficiency they can get through combined cycle and heat recovery systems. These systems provide significant increases in efficiency. Another reason is the torque produced from electric motors is more applicable to the jobs these ships are performing. This whole HP discussion is pointless because the torque curves are the most important. You want a 80 HP DC brushless motor? I think you also want some broken couplings and bent shafts. A less powerful electric motor can turn a bigger prop than a more powerful diesel just like a less powerful diesel can turn a bigger prop than a gasoline motor. And a bigger prop typically means better prop efficiency.

Now back to cruising sailboats. I believe that series diesel electric propulsion is not applicable for long distant cruising. It has too many areas to loose power/energy and a diesel running at its designed RPM will out perform in efficiency. However I do like the idea of the parallel diesel electric propulsion. If you want to motor for long times run the diesel. If you want to move around in the marina use the electric. And if you want power while sailing, most electric motor controllers can act as generators. Since once you get to hull speed a little extra drag won't hurt.

In addition the golden jewel to this system would be somehow converting wasted heat from the diesel engine into electric power through something like the Cyclone Heat Recovery Steam Engines. But will the price be worth it? Who knows till someone designs it and a control system to sell to the public.

[a64pilot]

It's the Atkinson cycle engine that allows me to get 60 MPG at a steady state 60 MPH on our Prius, the electric part of the car isn't used much at steady state highway driving. People that hypermile a Prius learn early on, it's most efficient to not use the electric part of the car, to use the ICE for propulsion, then coast as much as possible.
If you decelerate normally, the friction brakes are used only below 5 mph, the point where regen doesn't work, driven properly a Prius brakes should never need replacing.
A lot of unusual things on the car, nothing is driven off the engine directly, even the water pump and brakes are electric, power steering, airconditioning etc., as such they can all be variable speed and run not at engine RPM, but only as fast as required.
Prius has the capability at lower city speeds (42 MPH) of being electric only and then running the engine occasionally to re-charge and turning the engine off, so going down the road at city speeds, engine cycles on and off.
Very little if any of this is applicable to a boat, a boat is a steady state thing, usually fixed RPM, a lot like an airplane, yes you coud pull inot and out of the anchorage completly silently, then have the engine start as you needed more speed.

Boat Hybrid will be for those that want 120 or 220 VAC at all times, without the use of a generator, yes the generator will have to run intermittantly, but not all the time.
I believe it's biggest proponents will be the wealthy that want a new toy to brag about at the cocktail party and invite people out on a day sail and brag about how Green they are.
I'm not belittling that, automobiles, boats, airplanes, TV's, Radios, all kinds of things started out as rich peoples toys, and if not for them, maybe people like me would never have had them.
But for the forseeable future, if your at all concerned on what your cruising budget will be, or how much does it cost, a Hybrid boat is not likely very soon.

[JayWit]

Let's be honest the Prius is not really a good argument for marine hybrids. Yes some of the technology, mostly batteries, can be carried over but the Prius is on land, brakes, and travels at 70 mph on the highway. The Prius was engineered to tackle fuel efficiency of cars not sailboats.

[DeepFrz]

One further plus on the diesel electric system is that the generator can be mounted in a location easy to service instead of in a pit with access for midgets, contortionists and young flexible people. I love the idea of the azipod. No dripping or dripless packing glands.

Something that bothered me though about the video of the Torqueedo system was the fact they showed the gunboat slicing through the water under sail but it was a simulation they showed of the docking system. I guess the product is still under development.

[Cheechako]

Originally Posted by JayWit

Let's be honest the Prius is not really a good argument for marine hybrids. Yes some of the technology, mostly batteries, can be carried over but the Prius is on land, brakes, and travels at 70 mph on the highway. The Prius was engineered to tackle fuel efficiency of cars not sailboats.

I agree, but my real point was: given enough emphasis by a company that wants to make it work... it could.
I still wonder why a hydraulic drive motor wouldnt be better though... no huge battery bank! Too much HP required?
Here's a Kubota 4wd hydraulic in action:

https://www.youtube.com/watch?v=6o0YlvqE-Ss

I used on of these for a few days last year. man did I get a lot of work done... and burned very little fuel..

[a64pilot]

Very little if any of the Prius is applicable t a boat, I think, except maybe to show Hybrid is feaseable.

As far as Hydrostatic drive, it's possible of course, it's less efficient than direct drive, but does allow great flexibility as to where to mount the engine / pump, but I think th ewhole purpose of a boat Hybrid is to have the massive battery bank, but to have the flexibility as to how that electric power is used.
I believe the intent is to have a pratical electric powered boat, the engine is an unwanted requirement, sort of like now, I'd rather do without the thing if I could, I'm just not willing to make the sacrifices necessary to go without a Diesel

[skipmac]

Originally Posted by Cheechako

Actually I've driven rented Prius' 100's of freeway miles with no issues at all.... very little braking involved.

We own a Prius and do a lot of highway driving. The only difference I see is the fuel consumption is a little higher than in town where the braking recharges the batteries. Runs well and has enough power to win an occasional citation of the wrong kind.

I think we get +40 mpg on the road and almost 50 town.


By the way, there are three Prius's in my immediate family, one at least ten years old and never any trouble with brakes.

[JayWit]

Originally Posted by Cheechako

I agree, but my real point was: given enough emphasis by a company that wants to make it work... it could.
I still wonder why a hydraulic drive motor wouldnt be better though... no huge battery bank! Too much HP required?
Here's a Kubota 4wd hydraulic in action:

I used on of these for a few days last year. man did I get a lot of work done... and burned very little fuel..

Are you saying use a diesel to run a hydraulic system to run the propeller? If so that would be like running a really inefficient transmission. Great for a 4x4 tractor with a front end loader that only goes 15 mph on land. The issue with hydraulics is the faster you get the fluid moving the higher the Reynolds number (Turbulent Flow) therefore heat/energy loss. Plus hydraulic leaks are a pain.

[JayWit]

Have you replaced the batteries in your Prius yet? If so, how much did they run and what voltage is the pack configured for?

[JayWit]

If you don't want an engine get rid of it and use the sails. If you want to get the most distance out of your fuel use a really efficient diesel with a large variable pitch propellor. If you want to power an AC unit and TV's use a diesel electric system.

I just love the fact that you can generate electricity from the turning propellor. Just imagine in fair winds running a 500 watt sound system playing "Don't Rock the Jukebox" by Alan Jackson and not having to turn on the genset to mess with your music.

[misfits]

There are quite a few boats out there that have been converted to EP. It seems most that make the conversion are very happy with their decision. Are there limitations for motoring long distances with EP, yes but these are "sail" boats.