Diesel Electric Propulsion

[Julie Mor]

A couple of years ago we met a couple in Annapolis. During our conversation they mentioned they were starting a company specializing in electric motor propulsion for sailboats. We got the chance to visit their business, Annapolis Hybrid Marine, and see how the system worked.

I liked the concept and the particular setup they had in their shop seemed like a great option for getting a boat in and out of the harbor but not so good for any long range cruising.

In an article I recently read in the Jan. '15 SAIL issue, they featured this same setup being installed in a 30 ft. Irwin. In the article they also mentioned Oceanvolt and Torqueedo as having inboard electric motors with more HP than the AHM motor. This seemed like a green solution for most any sailboat.

The idea is to use a generator, coupled with the electric motor. The generator would be on-demand and variable speed and charge the batteries as well as provide any other power needs your boat would have. The on-demand, variable speed generator would be more energy efficient than simply running a big engine designed to take the boat to maximum speed. Large ships today have electric motors turning the screws and many have the azipods setup in place, providing better maneuverability, another plus.

For boats with auxiliary and generator already in place, this would seem a good option when that time came to overhaul or replace the auxiliary.

Does anyone here have this system in place? Do you know anyone who does? What do you think? Is this the future?

[a64pilot]

Issue I believe is $$$

It will work, has worked since WWI submarines?

[Sailmonkey]

What a64 said, plus the usual problem of either having a generator way oversized for house loads when not propelling, or a huge batt bank. Diesel electric works on ships as a way to change engine room configurations or improve maneuverability.
Several years ago a company called fast electric yachts took the generator/motor components from a hybrid bus and installed them in a 30 something foot cruisers yacht. Primary benefits were reduced fuel consumption (single diesel as opposed to twin gas) and better distribution of weight (single engine athwart ship fwd) however the vessel still had an auxiliary generator for house loads. The auxiliary gen also doubled as a come he engine.


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[DeepFrz]

One of our members here has converted his boat to electric drive. He has had it running successfully for a number of years and loves it. I believe he has a small Yamaha generator in case of emergency but gets most of his power from solar energy when he is away from the dock. I still have doubts about how this would work for a long distance cruiser but LiFePo4 batteries should make it much more doable...although maybe a little expensive.

[Julie Mor]

From what I've read, the technology in today's market is still a bit pricey. The guy with the 30' Irwin paid $9,500 for the motor, controller, battery charger & monitor, mountings, cables and a few other things. Then he bought four deep cycle AGM batteries for another $1,300. He said that was more than a new diesel engine and transmission.

But he had battery power he never had before, an "engine" that produced 20HP yet only weighed 47 pounds. And it was much cheaper and easier to maintain. Plus no diesel fuel smell, no noise and no exhaust fumes.

One of the things I can see that will help make this technology grow comes in replacing the auxiliary engine with a generator. Manufacturers choosing to adopt these systems can boast of their boats being green AND tell prospective buyers, "Whatever conveniences you're used to at home you can have on board." Generators will no longer be a luxury but will become as standard as the inboard auxiliary. And for those who have been used to having a generator and have two engines to maintain, they now only have one.

Who knows, maybe in time we'll see azipods on recreational boats instead of bow thrusters. Bigger boats may have both and be able to turn within their LOA. I think this is the future.

[Julie Mor]

Seems Torqeedo already has a video that exceeded my imagination:

https://www.youtube.com/watch?v=Px-9DIc3wik

[rockDAWG]

We are not there yet. The small internal combustion engine and generator are very inefficient on the boat. Unlike the power plant, it is much more efficient to produce electricity per gram of fuel used.

For hybrid to work,
1. we have to have a better mean of converting sun light to energy. Today photovoltaic are hundred folds less efficient than photosynthesis used in plants.
2. We need a better generator
3. We need a better battery

I am sure one day, we will be there, but not now.

[a64pilot]

It is available and is done now and has been for quite some time.
Watched a video the other day of a modern J boat that was built in Holland I think, but anyway one of the things they were talking about was it's electric drive, plus it had enough battery capacity to run everytihg overnight, I'm sure that meant AC and whatever lese a Billionaire would want.
I've not seen the torquedo video, but I can tell you my opinion of how it would work.
1. not LA batteries, for many reasons
2. A generator sized so that it's output would drive the boat at about half hull speed indefinately, which is probably less than 25% of a standard engines HP? not enough power to claw yourself away from a lee shore maybe, but with full batteries and a generator you would have a coupe of hours hull speed available and that should be eough to get yourself out of danger, and if you thought you may need power, of course get a full charge in early.
I don't see it being a variable output generator either, run it at it's most efficient load / RPM and have a bank sized so it can take all the generator can put out, bank full, generator shuts down. I see water heater using waste heat off the generator and cooking still being propane.
Problem is this system will cost way more than a standard Diesel will, but for those that want it, and can afford it, it's available now

[a64pilot]

OK, watched the Torquedo video, I'll be nice and say they are being in my opinion a little optomistic on at least the power available from Solar, and I believe with the Azipods, wau more complex than necessary, but I don't see why it wouldn't work in theory. I think electric cooking is a foolish waste of power, but that is just my opinion.

Anybody know the cost of the system? Bet it's more than most boats cost.

[goboatingnow]

I see no advantage, since you cannot yet remove the need for a IC engine., you might as well use it for propulsion.

[manitu]

Diesel-electric, sometimes with hydraulic back-up transmission is the way most fishing boats are built, for many years now. A fishing boat spends days on end at very low speed, where the electric motor beats the diesel hands down on efficiency. the diesel can run at peak torque when it needs to charge.

In a vessel wich usually runs at 80% or so, you will not see any noticeable fuel saings.

.manitu

[garrobito]

Still be pricey but absolutely possible...
Every day I saw new things coming about electrical propulsion..
The new electrical motor with rare mineral produce an incredible strong magnetic pulse, enough to move a full hull at comfortably 9 kt.
2 questions still floating on the air.. AC or DC propulsion?? AC seems like the easy way but the cost of controller when you scale up it's unbelievable.. DC don't have enough power to move a boat across the ocean for years.. beside.. even if you add a generator still be an option more heavy and less economical in the long time.
I did a couple conversion.. like somebody pointed, it's about $10/15K between kit, batteries, cables, etc, etc.. mostly times you need to replace the propeller..
Advantages.. pure power, silence, zero emission, no gas onboard, and your reducing your footprint on the planet...
I strongly suggest for everybody who want or need an engine replacement...

[jongleur]

... less efficient than photosynthesis used in plants...

Funny how the goalposts are constantly moved back for solar.
As solar is approaching the economy of fueled
charging, (which by the way is also much less efficient than
photosynthesis used [by] plants) I've never heard that strange
objective, meaningless as it is.

[skipmac]

After much reading and research on electric power it comes down to this.

1. Commercially available systems are much more expensive than a standard diesel including the transmission. Some as much as double or triple the cost.

2. Have not yet seen a commercially available system that has power equivalent to my 58 HP diesel. Most top out around 12-25 kW (16-32 hp).

3. Even if you fill a boat with batteries and solar to charge you will only get a few hours under power. To get more range you will have to add a generator so now you're back to having an engine with the fuel and smell and maintenance that you were trying to get rid of. Plus you have added even more cost.

My conclusion, electric is fine for smaller boats for short runs like dock to channel, mooring to the bay, etc. Anything more, it's not yet ready for prime time.

[senormechanico]

Originally Posted by jongleur

... less efficient than photosynthesis used in plants...

Funny how the goalposts are constantly moved back for solar.
As solar is approaching the economy of fueled
charging, (which by the way is also much less efficient than
photosynthesis used [by] plants) I've never heard that strange
objective, meaningless as it is.

Maybe this means for maximum efficiency we should be burning plants (wood) in a steam engine for propulsion?