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Electric motor and propeller selection for electric/hybrid boats


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A request which I suspect will fall on deaf ears -- we've been over all this before multiple times with no conclusion, can we avoid pointlessly recycling the same arguments?

 

Just for once it might be nice to keep a thread about electric boats on the (technical) subject instead of getting into the charging points debate yet again... 🙂 

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Battery swap stations will be needed. AND Charging stations. You need both for the system to work properly.

 

I know Tesla like all their supercharger and hyper factories and gigawotsits but at the end of the day mass adoption can't happen if you don't also provide the option to change the battery.

 

NIO have got this worked out but they are a bit behind with production. I'm looking forward to watching them rapidly take over Tesla as the world's no.1 electric car producer.

 

 

 

 

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1 hour ago, Alan de Enfield said:

 

But that is only C&RTs share - there are some 90,000 boats registered in the Inland waterways - remember whilst C&RT may be one of the biggest Navigation Authorities, there are 26 more besides C&RT.

It is still a very small number of boats amortised against the huge cost of X.000 charger units and associated cabling and ground works.

 

There are also 250,000+ leisure boats around the coast, but, most of those will be in Marinas so an electrical supply (of some sort) should be available.

 

I hadnt even considered the wider picture for coastal/offshore yacht-ists and motorboat sailors. 

The engine for these boaters can be critical to safety in some situations, surely? 

What would they do on say a transatlantic voyage, in winter or with less than optimal solar?

They can't really afford for their engine to run out of charge. Will an electric motor and batteries give them the level of safety they need? Presumably the powers that be have looked at all this before they pronounced the 2050 date (and the others), so I guess the answer must be yes. And the new electric designs will be coming out to sail in increasing numbers as the years go by.

I was thinking that the relatively small number of narrowboaters might turn out to be a benefit, in that it might be easier for the relevant govt authorities to let them go under the radar and carry on using ICEs for another decade or so.

But as you say, there will be many other small groups of ICE users who will also be hoping for exemptions to be granted. But for all of them, there will be a case to made for them to continue with ICEs until some charging infrastructure is in place.

It is the slow development of that infrastructure, if anything, that will cause a delay to the 2050 deadline for some groups of boaters. 

That said, if by 2050 things are as bad climactically as we fear they might be, then the concerns of leisure boaters and their ICEs may not matter much, even to the boaters. We will be too busy coping with massive international population stresses caused by huge floods, billions suffering famine, etc.  

 

 

1 hour ago, IanD said:

A request which I suspect will fall on deaf ears -- we've been over all this before multiple times with no conclusion, can we avoid pointlessly recycling the same arguments?

 

Just for once it might be nice to keep a thread about electric boats on the (technical) subject instead of getting into the charging points debate yet again... 🙂 

 

Sincere apologies Ian, I reached straight for my pearls and started clutching them as soon as I saw the phrase 'electric motor'. 

You triggered me 😂

 

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2 hours ago, magnetman said:

Battery swap stations will be needed. AND Charging stations. You need both for the system to work properly.

 

I know Tesla like all their supercharger and hyper factories and gigawotsits but at the end of the day mass adoption can't happen if you don't also provide the option to change the battery.

 

NIO have got this worked out but they are a bit behind with production. I'm looking forward to watching them rapidly take over Tesla as the world's no.1 electric car producer.

 

 

EV battery swaps have been proposed and rejected many times for various reasons (technical and business), with a few exceptions like Nio which will probably only work in the Chinese market -- huge, with tight government control not driven by "the market". You need a standardised battery -- which all the Western manufacturers hate with a vengeance because it stops them differentiating their cars -- plus huge infrastructure investment in battery swapping and all the batteries that *aren't* in cars, plus having to either move them between stations to meet demand or -- the likely Chinese option -- force people to drive to where the batteries are. All of which works in a command economy like China where companies and people do what the Party tells them, but not in the West.

 

You could say this is one reason China is successful, if the Party says something must be done then it happens regardless of any negative consequences -- like when the Foxconn suicides happened just before I was in Shenzhen, the decision was rapidly made to build satellite factories in the provinces near worker's families. Six months later the first one -- for 70000 workers IIRC -- was up and running. No waiting for planning permission or consultation, just raze any villages in the way and do it.

 

Fantastic for business/economic success for the country -- it's basically a dictatorship driving commerce -- but complete anathema to Western democracies and companies, even if it delivers economic success for China.

 

All the reasons that EV battery swapping could work in China are the same reasons that it won't work in the decadent West -- which is pretty much controlled by corporations (and has multiple uncooperative governments), not the monolithic CCP.

 

Dammit, all that after I said I wanted to stick to the original subject... 😞 😞 😞

Edited by IanD
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1 hour ago, Tony1 said:

What would they do on say a transatlantic voyage, in winter or with less than optimal solar?

 

The govenment is only making the legislation for UK territorial waters so cannot make any transatlantic (or other boats / ships) comply.

They can only legislate for UK registered boats, and make life difficult for visiting "foreign boats".

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6 minutes ago, Alan de Enfield said:

 

The govenment is only making the legislation for UK territorial waters so cannot make any transatlantic (or other boats / ships) comply.

They can only legislate for UK registered boats, and make life difficult for visiting "foreign boats".

Global shipping is a CO2 problem on a scale that makes the UK canals fade into insignificance, as is aviation, concrete...

 

There's nothing CART and the UK government can do to fix these problems; there are things they could do to enable their zero-emission targets to be met on the canals. Focus on the things you can change, not the things you can't... 😉

 

-- and don't use "Woe is me, I can't fix everything!" or "Somebody else is worse than me!" as excuses to do nothing -- because if *everyone* does this, the planet is f*cked... 😞

Edited by IanD
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1 hour ago, Peanut said:

Ian, from a technical perspective, doesn't prop pitch come into this?

 

 

Yes, pitch and diameter, as I said in the first post.

 

The power absorbed by a prop is roughly proportional to rpm^3 * diameter^2 * pitch. So for a given power and rpm you can trade off pitch and diameter, for example these will all be roughly equivalent:

 

Diam  Pitch  P/D

20      9.7     0.49

19     10.8    0.57

18      12      0.67

17      13.5   0.79

16      15.2   0.97

 

It's also known that for slow-speed boats like narrowboats (or tugs or trawlers) the best propeller efficiency and bollard pull -- "stopping power" -- is with P/D around 0.6 to 0.7 -- much smaller than this (e.g. <0.5) and more energy is wasted dragging big small-pitch blades around, much bigger than this (e.g. >1.0) and more energy is wasted in the rotating wake because the blade angle is too big.

 

This is why the recommended props for most narrowboat engines fall in this region, for example from the Beta Marine website (with 2:1 gearbox):

 

Engine      Diam  Pitch  P/D

Beta 30    15       9       0.60

Beta 35    16      11      0.69

Beta 43    18      12      0.67

Beta 50    19      12      0.63

 

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6 hours ago, IanD said:

 

Yes, pitch and diameter, as I said in the first post.

 

The power absorbed by a prop is roughly proportional to rpm^3 * diameter^2 * pitch. So for a given power and rpm you can trade off pitch and diameter, for example these will all be roughly equivalent.

 

6 hours ago, IanD said:

Thank you, I found the relationships between rpm, diameter and pitch interesting. My next question would be how much of the power, absorbed by the propeller, produces useful work in terms of thrust.  Presumably, this is the force produced by a bollard pull.  If this were taken as a measure of efficiency, how would the pitch and diameter affect this at narrowboat speeds.  A tender outboard is specified with a high thrust propeller due to its use at lower speeds.

 

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On 21/11/2022 at 15:01, magnetman said:

Battery swap stations will be needed. AND Charging stations. You need both for the system to work properly.

 

I know Tesla like all their supercharger and hyper factories and gigawotsits but at the end of the day mass adoption can't happen if you don't also provide the option to change the battery.

 

NIO have got this worked out but they are a bit behind with production. I'm looking forward to watching them rapidly take over Tesla as the world's no.1 electric car producer.

 

 

 

 

It will flop like it did for Renault and Tesla dismissed it quite rightly as a waste of valuable and expensive materials.

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For me with my Agni motor and gearing Cedric Lynch gave me instructions on how to get the load right for the motor. Its a DC motor so the best it can do is 90 odd %, anyway you connect a meter to the batteries and measure voltage, you connect a meter to the motor as well, an old AVO in my case as the speed controller is PWM and it might or not work with a modern meter. Then you get someone to accelerate gently watching the voltage on both meters up to about half throttle, what you want is both to be very close to each other in voltage readings. In my case they are but weren't at first, the motor had to much load so a bigger pulley was needed, which sorted it out.

The motor at full throttle can hit nearly maximum rpm so it's near as dammit perfect.

My motor and controller both run cool which is a success. 

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10 minutes ago, peterboat said:

For me with my Agni motor and gearing Cedric Lynch gave me instructions on how to get the load right for the motor. Its a DC motor so the best it can do is 90 odd %, anyway you connect a meter to the batteries and measure voltage, you connect a meter to the motor as well, an old AVO in my case as the speed controller is PWM and it might or not work with a modern meter. Then you get someone to accelerate gently watching the voltage on both meters up to about half throttle, what you want is both to be very close to each other in voltage readings. In my case they are but weren't at first, the motor had to much load so a bigger pulley was needed, which sorted it out.

The motor at full throttle can hit nearly maximum rpm so it's near as dammit perfect.

My motor and controller both run cool which is a success. 

Sorting this out is a lot easier with a modern PMAC motor and controller, these can directly measure everything you need to know -- motor rpm/torque/power/temperature, controller current/temperature and so on, and you can then compare these with the motor design curves to see if the prop (or gearing if any) is correct.

 

You can also set torque limits so if the prop gets badly fouled the motor stops almost instantly instead of wrapping whatever you've caught tightly round the prop, stalling it and then taking loads of current. Of course this has to be balanced with carrying on turning to throw off weed, so some trial and error is needed... 😉

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23 hours ago, peterboat said:

It will flop like it did for Renault and Tesla dismissed it quite rightly as a waste of valuable and expensive materials.

 

Easy enough to say but with the rapid improvements in battery technology it seems to be a different story. Tesla is old news.

 

As for boats what's not to like about getting a battery exchange module in to add some range so you can cruise to that nice quiet spot away from the madding crowd?

 

People bunker diesel, coal, gas and even beer so why not batteries?

 

You do need to have a main battery which is rechargeable but I don't see the problem with having the option of a removeable module for extending range.

 

its going to be a bit heavy but with forecasts of 350wh/kg energy density you would be talking about a 20kg battery (7Kwh) for an hour and a half slow cruise if the boat is using 4.5kw to go along.

 

Stopping power is a red herring. Just learn to handle a boat and anticipate what is going to happen. They had to do this all the time with horse boats. No reverse. 

 

 

 

 

Edited by magnetman
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41 minutes ago, IanD said:

Sorting this out is a lot easier with a modern PMAC motor and controller, these can directly measure everything you need to know -- motor rpm/torque/power/temperature, controller current/temperature and so on, and you can then compare these with the motor design curves to see if the prop (or gearing if any) is correct.

 

You can also set torque limits so if the prop gets badly fouled the motor stops almost instantly instead of wrapping whatever you've caught tightly round the prop, stalling it and then taking loads of current. Of course this has to be balanced with carrying on turning to throw off weed, so some trial and error is needed... 😉

I ain't disagreeing with you, my controller is an issue with the above, I think the 4QD controller might be better, it most certainly can do the functions you list? But that's a job for next year

Edited by peterboat
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1 hour ago, magnetman said:

 

Easy enough to say but with the rapid improvements in battery technology it seems to be a different story. Tesla is old news.

 

As for boats what's not to like about getting a battery exchange module in to add some range so you can cruise to that nice quiet spot away from the madding crowd?

 

People bunker diesel, coal, gas and even beer so why not batteries?

 

You do need to have a main battery which is rechargeable but I don't see the problem with having the option of a removeable module for extending range.

 

its going to be a bit heavy but with forecasts of 350wh/kg energy density you would be talking about a 20kg battery (7Kwh) for an hour and a half slow cruise if the boat is using 4.5kw to go along.

 

Stopping power is a red herring. Just learn to handle a boat and anticipate what is going to happen. They had to do this all the time with horse boats. No reverse. 

 

 

 

 

Tesla arnt old news, at a port in the South thousands of orderered and paid for Tesla's are waiting to be moved, if you look around Tesla are the dominant EV and that wou8be changing any time soon. 

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13 hours ago, magnetman said:

 

Easy enough to say but with the rapid improvements in battery technology it seems to be a different story. Tesla is old news.

 

As for boats what's not to like about getting a battery exchange module in to add some range so you can cruise to that nice quiet spot away from the madding crowd?

 

People bunker diesel, coal, gas and even beer so why not batteries?

 

You do need to have a main battery which is rechargeable but I don't see the problem with having the option of a removeable module for extending range.

 

its going to be a bit heavy but with forecasts of 350wh/kg energy density you would be talking about a 20kg battery (7Kwh) for an hour and a half slow cruise if the boat is using 4.5kw to go along.

 

Stopping power is a red herring. Just learn to handle a boat and anticipate what is going to happen. They had to do this all the time with horse boats. No reverse.

 

 

The problems with battery exchange -- as I wrote earlier, but you don't seem to have read -- are both technical and economic.

 

The technical problems include how to load/unload and connect/disconnect large/heavy batteries -- which can be overcome, but adds cost to the vehicle (car/boat) and a *lot* of cost to the charging station, and has significant H&S problems (automated/robotic handling of hundreds of kg of batteries without crushing anyone) especially for a boat. It's not like dropping some D cells into a battery compartment... 🙂

 

The economic problems include the fact that for such a scheme to work all the batteries have to be the same -- more of a problem for cars, but still a downside for boats -- and the fact that there need to be charged batteries "in stock" at the charging stations. This again puts the cost up (more expensive batteries on shore needed on top of the ones being used in boats), and on top of this there's the difficulty of keeping charged ones "in stock" at places/times of high demand -- if you have to wait for one to be charged up for you when you arrive because the last charged one was just used, you might as well just plug in and charge. There's also the "who owns the batteries" problem, and how to stop people driving/sailing off with a nice new battery but coming back with an old knackered one with the same faked serial number, and many other problems...

 

If battery swapping worked then cars would have widely adopted it, because it would remove the charging time/range anxiety worries. The fact that it hasn't been adopted** says everything... 😉

 

** except in a case like Nio in China with a massive market and a system where a car manufacturers do what they're told by the CCP whether they like it or not -- will never work in the West...

Edited by IanD
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16 hours ago, peterboat said:

Tesla arnt old news, at a port in the South thousands of orderered and paid for Tesla's are waiting to be moved, if you look around Tesla are the dominant EV and that wou8be changing any time soon. 

The latest figures I can find for global BEV sales:

 

https://insideevs.com/news/601770/world-top-oem-ev-sales-2022h1/

Battery-electric only (BEV)

In terms of all-electric car registrations, Tesla remains the king (over 564,000), but its market share decreased by another few percent to 19%. That's still a lot - almost one in five new BEVs globally.

However, BYD again shines with over 326,000 units and doubled market share year-over-year to 11%.

 

That's enough to overtake SAIC (incl. SAIC-GM-Wuling micro cars) and strengthen its advantage over Volkswagen Group, which both lost some market share as well.

Hyundai Motor Group remains the fifth largest OEM in the BEV segment with over 167,000 units and 5.6% share, followed by Geely-Volvo (4.3% share).

All-electric car registrations in H1 2022 (vs previous year):

  1. Tesla: 564,873 and 19% share (vs 22.7%)
  2. BYD: 326,236 and 11% share (vs 5.5%)
  3. SAIC (incl. SAIC-GM-Wuling): 321,289 and 10.8% share (vs 14.5%)
  4. Volkswagen Group: 216,004 and 7.3% share (vs 10.7%)
  5. Hyundai Motor Group: 167,305 and 5.6% share

Top 5 total: 1,595,707 (53% share)
others: about 1.4 million (47% share)
Total: about 3 million

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Mass market needs cheaper cars.

 

I think Tesla have a lot to fear from chinese manufacturers undercutting them.

 

Like this example. Better Wh/mi than a Model 3 and at least ten grand cheaper. Same basic platform design.

 

https://en.wikipedia.org/wiki/Shenlan_SL03

 

Seems an interesting car but not all that straightforward to get it to non chinese consumers to be fair.

Edited by magnetman
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The way CRT funding is (probably) headed, the debate about propulsion in 2050 is academic.  The few bits of the canal system with water in by then will be a linear slum.

 

N

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3 minutes ago, BEngo said:

The way CRT funding is (probably) headed, the debate about propulsion in 2050 is academic.  The few bits of the canal system with water in by then will be a linear slum.

 

N

 

Of course you could say the same about roads, or climate change, or global food/water supplies, or the canals -- OMG it's all going to hell in a handbasket, there's no point doing anything or planning for the future, it's all going to turn to sh*t so let's just give up and carry on as we are... 😞

 

Alternatively we could try and find ways to improve things and stave off the apocalypse; electric propulsion on boats is a tiny brick in this wall (much smaller than EVs) but nevertheless worthwhile... 😉

 

 

Edited by IanD
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2 hours ago, magnetman said:

Mass market needs cheaper cars.

 

I think Tesla have a lot to fear from chinese manufacturers undercutting them.

 

Like this example. Better Wh/mi than a Model 3 and at least ten grand cheaper. Same basic platform design.

 

https://en.wikipedia.org/wiki/Shenlan_SL03

 

Seems an interesting car but not all that straightforward to get it to non chinese consumers to be fair.

 

This could be the next step after the Korean EV onslaught. A few years ago the likes of Kia and Hyundai were written off as cheap low-end Korean crap that nobody who could afford anything better would drive; now they're being rated as top of the class and collecting multiple awards, not just for being good value but being the best.

 

Nothing stops China doing the same in the near future and churning out good EVs at even lower prices than Korea -- writing them off as cheap rubbish could be a fatal mistake for Western car manufacturers... 😞

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