New design for Electric jet propulsion

[bthessel]

This ground-breaking water jet could jump-start the electric boats revolution

www.mby.com

It makes a lot of sense, if you think about electric cars some of the efficiency comes from the motors being directly attached to the wheels, not trying to retrofit a big electric motor to replace a gas engine.

 

[Miitch]

Something about the thought of large Lithium ion batteries floating on the water just makes me feel uneasy...

 

[Julian]

Something about the thought of large Lithium ion batteries floating on the water just makes me feel uneasy...

Not sure that batteries vs large tanks of highly combustible fluids are a lot different. For range, they'll all need to be hybrid (Diesel/Electrics) but that isn't an unusual combo - trains have been doing that for decades.

Looks interesting....will be fascinating to see if they can make it work - start off with the diesel/electric combo first to prove the drive system, then when batteries catch up, use them for shorter distance runabouts/tenders etc.

 

[mrcleanr6]

this is basically an azipod which have been around forever and what is on most cruise ships. only difference is it would use an impeller vs a regular prop like an azipod does.

 

[Miitch]

Not sure that batteries vs large tanks of highly combustible fluids are a lot different.

Im more worried about what happens if the boat decides to go scuba diving. Id much rather swim in my own gasoline than be anywhere near a Lithium ion battery when it touches water. Lithium reacts violently with water. Similar to those videos of kids throwing sodium metal into water, only much much worse. That on top of the fact that high temperatures can cause a thermal runaway reaction with batteries of the sort, spells danger IMO.

 

[Julian]

this is basically an azipod which have been around forever and what is on most cruise ships. only difference is it would use an impeller vs a regular prop like an azipod does.

Actually I have to disagree.....they make 3 points that are different than the current pods:

1. the electric pod design eliminates all the linkages and associated friction and power loss by putting the electric motor in the pod itself.
2. the combined system weighs less (supposedly) (no transmissions etc)
3. the drive system is more efficient than either a propeller or a waterjet through the entire rev range, even at low speeds where waterjets usually struggle - the interesting part here is their graph. They are saying they don't have a big drop off like props do at top rpms.....time will tell.

 

[AZMark]

That’s an awful lot of stuff to have dragging in the water causing resistance.
The jet system in our boats is pretty efficient as far as water flow goes. It moves up a couple inches but is still forced in by the speed of the boat. Jet skis have scooped intakes and our boats could use the same if increasing this effect was that favorable and desired.
We also don’t have any transmission or joints for mechanical losses.

 

[AZMark]

That’s an awful lot of stuff to have dragging in the water causing resistance.
The jet system in our boats is pretty efficient as far as water flow goes. It moves up a couple inches but is still forced in by the speed of the boat. Jet skis have scooped intakes and our boats could use the same if increasing this effect was that favorable and desired.
We also don’t have any transmission or joints for mechanical losses.

Now if that thing could change the pitch of the blades it would be pretty amazing.

 

[Julian]

That’s an awful lot of stuff to have dragging in the water causing resistance.

That is what I thought too! I would have thought it would have a sharp edge on the front more like a straw that tapers.

 

[tdonoughue]

One of the advantages to electric drives is instant torque. In an internal combustion engine, you have maximum torque at speed. For an electric motor, torque is peak at 0 rpm and drops off as you get faster. Because of this, replacement of the power plant is not as simple as 'just drop in an electric one'. I wonder if the new form factor handles things like cavitation at low speeds better or something.

Also, though I know they call out LiIon batteries, I would not be surprised to find them start with gels or something more conventional to start out... I do agree LiIon's on the water would be a risk, but I am sure they would do what they do with cars (multiple layers, etc.). If you think about it, the risk is probably not greater than an automobile (where it could wreck in the rain with similar bad effects, only with more people around, generally).

 

[Elliott]

It is all interesting, and I wish them luck. However, we are a long way from anything that is battery powered providing significant range or the ability to do a serious amount of work. The terrible truth is that current batteries do not have the energy density required to match oil based fuels - especially if cost is factored in to the equation. Today's best electric vehicles are small, with limited range and require significant time to recharge.

I guess I could get an electric vehicle experience with my Tundra. I could replace the 38 gallon tank with a 15 gallon one, and I could restrict the fuel filler hose to make it take 30 minutes to fill the tank. ?

Japanese auto manufactures seem to be some of the most capable in the world, and their best (most usable) products are hybrids. They certainly have an incentive to do better as Japan has no oil reserves.

 

[mrcleanr6]

Actually I have to disagree.....they make 3 points that are different than the current pods:

1. the electric pod design eliminates all the linkages and associated friction and power loss by putting the electric motor in the pod itself.
2. the combined system weighs less (supposedly) (no transmissions etc)
3. the drive system is more efficient than either a propeller or a waterjet through the entire rev range, even at low speeds where waterjets usually struggle - the interesting part here is their graph. They are saying they don't have a big drop off like props do at top rpms.....time will tell.

View attachment 140090

Actually concerning your [HASH=5612]#1and2[/HASH]. Azipods are electric with the motor in the pod. Its a massive submersible electric motor. There are no linkages or transmissions. As far as being more efficient than a prop or impeller like in our boats....that very well may be. There is really no data given to support that .

 

[corax]

Im more worried about what happens if the boat decides to go scuba diving. Id much rather swim in my own gasoline than be anywhere near a Lithium ion battery when it touches water. Lithium reacts violently with water. Similar to those videos of kids throwing sodium metal into water, only much much worse. That on top of the fact that high temperatures can cause a thermal runaway reaction with batteries of the sort, spells danger IMO.

its really not hard to make a waterproof box for batteries. which is what i plan on doing... a boat is a waterproof box for people... the tech needed is the same... seals latches grommets...silicone etc. without which no powered boat would function at all... buy or make pelican like cases... stuff them with 18650s.... is temperature ends up being a factor... put aluminum fins into the box design and cool them with fans or water....

you could plastidip individual cells and have next to nothing to worry about. Teslas need cell level cooling because of the high level drain depending on the range you need this could be a non-issue. the design factors adjust to meet the application. there are lithium ion batteries in the same form factor as lead acid, completely sealed which do not require cooling for example. just two lead posts sticking up from a plastic box like you are used to. dropping it in water would be mostly harmless.

 

[corax]

another fun thing to remember is that solid state batteries are now a reality. and will hit the luxury market first including boats