Electric Boat Propulsion

The technology for our electric boats is directly linked to the technologies being worked on in the automobile world,...which is advancing quite rapidly. We need to keep abreast of positives and the negatives. This subject thread is hopefully one that tries to keep abreast of both.

Not only the positives and negatives of the electric power sources (batteries, etc), but also the motor technologies. BOTH of these technologies are needed for our successful boat applications.

And there are currently some very exciting technologies appearing.

Motors:
1) China's Axial Flux Motor

2) Tesla's New Motor

Toyota's Solid State Battery Technology
I posted this video over on another subject thread,..
and received a fair number of replies,....many of them negative due to the claimed recharge times, and power needed to do that.

Now what if installed on a vessel with no need for rapid charging?

We get rid of that lithium-water-fire concerns?

Maybe we don't need this battery power for our motors,...just house power. The new small efficient electric prop motors might be powered via a small single diesel engine generator ?

Thanks for the references. There seems to be quite a lot of other issues to consider.

For example


and, of course for boats

I need lot of battery power .
I need to harvest energy from the wind.
I need to harvest energy from the sun .
I need high e-density battery .

Use any of electric device in the ocean enviroment is risky.
Give me, for example, some good waterproof connectors or quick-connectors .

We don't know how long the lithium battery era will last for transportation purposes. At some point research will produce much higher power density batteries that use oxygen from the air as the oxidizer at the anode, vastly cutting back weight -some possibly at the anode and some from replacing liquid or gel chemicals inside, using air instead, similar to the zinc oxide system but with lighter metals. The end goal may be based on some kind of a fuel cell concept which can operate on a hydrogen containing fuel at the cathode and oxygen from ambient air at the anode, hydrogen goal to be refilled quickly and carried on board as a stable solid like a metal hydride. Theoretically that could be much more efficient, because no huge heat losses while producing Electric fuel for e-motors and possibly distilled Quality Water as the exhaust. Compared to IC which uses the tiny exploding gases part for propulsion and wastes the great majority of energy contained in a gallon of petrol as heat which doesn't propel the vehicle; that heat is wasted/ dumped into the environment in additionl to the poisonous exhaust gases.

@rwatson
Good reply, and backed up with reference links.

interesting electric propulsion posting over here on this forum,..

O

Post in thread 'Multihull Structure Thoughts'

Sep 8, 2026

Co-founders Dan Hook and Rich Daltry of RAD Propulsion of Southampton England, developed an electric outboard company that started by working out the most efficient propellers to be used by an electric motor. The logic was: “What’s the most efficient prop we can give for a given thrust and speed? And then we worked our way back up the drivetrain, from the propeller up to the electric motor”.

Because electric motors produce incredible torque—the capacity to go from zero to maximum power almost instantly—they can swing bigger propellers than a gasoline engine. The 40-kW (equal to 55...

• oldmulti

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excerpt
Co-founders Dan Hook and Rich Daltry of RAD Propulsion of Southampton England, developed an electric outboard company that started by working out the most efficient propellers to be used by an electric motor. The logic was: “What’s the most efficient prop we can give for a given thrust and speed? And then we worked our way back up the drivetrain, from the propeller up to the electric motor”.

Click to expand...

It appears that axial flux motors are the latest craz in electric car development.

I've seen videos that indicate that Tesla is a leader in the developments, BUT also the Chinese,....which is it, or are they both leaders?


I do see that the Chinese version still includes magnets, which I believe Tesla says it does not need??

EDIT: And is this yet another competitor from Mercedes,...independent development or the origin of the basic idea like the Tesla one that needs no magnets??

I think that for marine use lead/acid is still viable. They are easy and cheap to recycle. For boats that travel at reduced speeds, the extra weight is not necessarily detrimental. On a motorsailer the batteries can be the necessary ballast. AGM batteries can withstand high C charge and discharge ratios. The usual discussions marry electric power to Li Ion batteries, but it doesn't need to be.

Of course electric propulsion is going to involve both new motor tech and new battery technology.
While I am interested in following both, I just believe it will be easier to see real advancements in motors over batteries??

I think more efficient motors are key to the development of electric systems. For the general public electricity appears to be an unlimited energy source that magically exits from an outlet. However, most countries have distribution grids that are overloaded or close to the maximum capacity. I believe this is going to be the new generation's major problem. We had awareness of pollution as one of the major issues. Sometimes the remedy is worse, or as bad, as the disease. For example, data centers are causing more environmental problems than when we used paper and developed photos. Most people are looking at taking hundreds of photos and saving every document on the cloud as saving trees. However, the energy to store them is more detrimental than storing paper files. I think that having electric cars that brag about how they can out accelerate a muscle car is not delivering the promise of being friendlier to the environment. In that vein, electric boats that promise to compete with gas guzzler go-fast boats may be, of will have to be, a dying breed.

More electrical energy is a big problem. Perhaps if we had pursued the French model of nuclear power plants of a similar type, and thus more serviceable, and thus safer,...we would be in a better position.

Too bad we can't save (and store-away) all of that solar power we are bombarded with on a hourly basis.

AFAIK, most e-motors themselves used for transportation are already around 90% efficient, so even with perfection only ~10% to be gained? Even without rare earth magnets, large induction motors can approach that level of efficiency. There was a posting quite a while back, regarding a no magnet industrial induction motor developed in India that was above 90%, as I recall. Also an electric "Wankel" design that used PM in both the rotor and stator so the each motor revolution was ~90% powered by free magnetic repulsion, but it quietly disappeared. But there may be bigger possible gains for the whole drive system by tweaking drivetrains and other components to match up with a particular motor's specs?

Batteries are very low in efficiency by comparison, mainly because of losses associated with conversion between the different forms of energy required for the propulsion process cycle. Electric energy to chemical energy losses when charging, then chemical energy losses to electric energy for feeding to the motor, plus internal resistance and possibly other losses both times in each cycle. Still much better than IC engines which use only the small explosion part for propulsion, and waste almost all the heat energy in a gallon of petrol, venting poisonous fumes and heat to the atmosphere. Electric power plants are better with fossil fuels, using much more of the heat energy and little of the explosion energy to generate power, compared to transportation applications. Nuclear produces forever lethal byproducts with long half lives, which would be extremely expensive to isolate /guard forever so that the public is protected from terrorist use and from health concerns when migration occurs into ground water, from accidents, from earthquake releases, etc. JMHO, have fun!

brian eiland said:

More electrical energy is a big problem. Perhaps if we had pursued the French model of nuclear power plants of a similar type, and thus more serviceable, and thus safer,...we would be in a better position.

Too bad we can't save (and store-away) all of that solar power we are bombarded with on a hourly basis.

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Canada has been using smallish nuclear plants that can't reach critical critical state. The fuel is in pellets with a core of enriched uranium. The ceramic layer keeps the fuel far enough that it can be left without cooling and it won't create a disaster. The massive American and Soviet nuclear plants were a result of the Cold War when they were trying to impress the world with their larger size. That is still influencing design in the USA.