Swapping from red diesel to HVO fuel

[peterboat]

1 minute ago, IanD said:

 

Go and check the actual efficiency curves for the motor that Lynch uses for narrowboats. Peak efficiency is 92%, but drops to 83% at full power (17% loss) which is when maximum power dissipation (heating) occurs. The Engiro motor is 93% efficient at full power (7% loss).

 

Its not the same motor I am using Ian, when they split Trevor could use the design he had however Cedric has constantly developed his motors to improve them ,they have different designations as well with different power outputs.  His rag motors are designed for racing and rev much higher without exploding!

[IanD]

43 minutes ago, PD1964 said:

I would say a lot more then 10%, are you just talking about the electric motor and not the vast bank of Lithium batteries, massive generator, Solar Panels, controller and the other electrics involved?

Not knowing the exact figure I would say  an electric engine set up like yours would cost £50K plus fitted(motor/controller, generator, lithium and everything else in the chain) maybe that’s why the boats have gone up from £180K ish to over £250K ish and more since fitting them???

 9kva Kholer generator well over £15K,  10% I don’t think so.

  

 

I meant the *difference* between the cheapest Lynch-based solution and the Rolls-Royce one, which is probably similar to the difference between a conventional diesel and the Rolls-Royce setup (including all the electronics), Finesse quoted a rough figure of £30k for this on their FB page.

 

Your price for the generator is also considerably too high... 😉

Edited July 27, 2022 by IanD

[PD1964]

15 minutes ago, IanD said:

 

I meant the *difference* between the cheapest Lynch-based solution and the Rolls-Royce one, which is probably similar to the difference between a conventional diesel and the Rolls-Royce setup (including all the electronics), Finesse quoted a rough figure of £30k for this on the FB page.

 

Your price for the generator is also considerably too high... 😉

I would say maybe you got the basic generator then, once you add all the silent gear, exhaust system, cabling, control panel etc and roughly looking on Google, you must of got a bargain price 😉

Edited July 27, 2022 by PD1964

[IanD]

9 minutes ago, PD1964 said:

I would say maybe you got the basic generator then, once you add all the silent gear, exhaust system, cabling, control panel etc and roughly looking on Google, you must of got a bargain price then😉

It's the Kohler 9EFKOZD which is already cocooned. I'm not buying it, it's part of the complete boat price from Finesse, but when I was looking at buying it and doing the system as DIY the price was certainly less than your figure. OTOH I know their prices have gone up recently, like everything else needed to build a boat... 😞

Edited July 27, 2022 by IanD

[IanD]

1 hour ago, peterboat said:

Its not the same motor I am using Ian, when they split Trevor could use the design he had however Cedric has constantly developed his motors to improve them ,they have different designations as well with different power outputs.  His rag motors are designed for racing and rev much higher without exploding!

Well that's the motor that Lynch uses for boat drives. If yours is different, go and look up the efficiency curves as used on your boat and post them, I'll wager it's not much different to the one I showed. How fast his motors go for racing is irrelevant.

 

What matters for motor cooling and heat dissipation is efficiency at full power not peak efficiency, and IIRC all the Lynch boat motors are in the low 80s here, which is about 10% lower than a modern PMAC motor -- it's just a fundamental feature of the pancake (axial flux) Lynch motor design, the winding losses and core hysteresis losses are higher. Which would mean that at the same power output their loss is 2.5x higher than PMAC, which means 2.5x more heat to remove -- and noisily using air cooling, not quietly using water cooling... 😉

 

How far is your wideboat steering position from your Lynch motor, and how much noise does it (and the bilge blower) make -- especially at full power -- if you stand right over it like on a narrowboat? The ones I've heard on narrowboats, you can hear the whine when they come past you, never mind when standing right over it... 😞

Edited July 27, 2022 by IanD

[peterboat]

3 hours ago, IanD said:

Well that's the motor that Lynch uses for boat drives. If yours is different, go and look up the efficiency curves as used on your boat and post them, I'll wager it's not much different to the one I showed. How fast his motors go for racing is irrelevant.

 

What matters for motor cooling and heat dissipation is efficiency at full power not peak efficiency, and IIRC all the Lynch boat motors are in the low 80s here, which is about 10% lower than a modern PMAC motor -- it's just a fundamental feature of the pancake (axial flux) Lynch motor design, the winding losses and core hysteresis losses are higher. Which would mean that at the same power output their loss is 2.5x higher than PMAC, which means 2.5x more heat to remove -- and noisily using air cooling, not quietly using water cooling... 😉

 

How far is your wideboat steering position from your Lynch motor, and how much noise does it (and the bilge blower) make -- especially at full power -- if you stand right over it like on a narrowboat? The ones I've heard on narrowboats, you can hear the whine when they come past you, never mind when standing right over it... 😞

How often do we use full power Ian? The answer is about 1% of the time, so in reality we are operating at maximum efficiency 90 odd percent of the time. So I am not far behind you in efficiency most of the time, not enough to worry about and cost wise I am about 20k plus ahead of you including my genny and all charging equipment. Ok I have spent my time but as a retired person I can live with those costs.

Now how quiet is my boat? I can just hear the blower and just hear some belt noise, I have a rug over the engine hatch which seems to have killed all issues. I am going to fit additional sound proofing for the genny and I think that will stop everything, I have the sound proofing for free so no cost just labour 

[IanD]

1 hour ago, peterboat said:

How often do we use full power Ian? The answer is about 1% of the time, so in reality we are operating at maximum efficiency 90 odd percent of the time. So I am not far behind you in efficiency most of the time, not enough to worry about and cost wise I am about 20k plus ahead of you including my genny and all charging equipment. Ok I have spent my time but as a retired person I can live with those costs.

Now how quiet is my boat? I can just hear the blower and just hear some belt noise, I have a rug over the engine hatch which seems to have killed all issues. I am going to fit additional sound proofing for the genny and I think that will stop everything, I have the sound proofing for free so no cost just labour 

Like I said, the efficiency is more of an issue when it comes to spending some time at full power -- like upstream on a river, which is the standard objection everyone comes up with to electric boats. Running at 83% with 15kW output you need to get rid of 2.5kW of heat into the air -- which is a tough challenge for a couple of hours or more on the Trent or the Ribble Link -- as opposed to 1kW into the water at 93%, which is dead easy. I know which I'd rather be on top of under those circumstances... 😉

 

(as you say, cruising at 3kW there's little difference, both solutions are maybe 92% and only have to get rid of 250W so no problem)

 

I keep asking but you keep not answering -- how far are you away from the motor on your wideboat? If you're some distance away up in a wheelhouse then you'll hear far less noise (from motor/belt/blower) than somebody on a narrowboat right on top of it, which is what most people are interested in. If you can just hear it from where you are, this could well be quite annoying on a narrowboat...

 

As I keep saying, it's a tradeoff between cost and heat/power/noise, there isn't one right answer -- your solution suits you (and it's cheaper, hotter and noisier), mine suits me (and it's more expensive, cooler and quieter). You pays (or saves...) your money and you takes your choice... 😉

 

(and the Waterworld solution is somewhere in between on all counts, which is the answer I was trying to give to the question asked)

Edited July 27, 2022 by IanD

[peterboat]

1 hour ago, IanD said:

Like I said, the efficiency is more of an issue when it comes to spending some time at full power -- like upstream on a river, which is the standard objection everyone comes up with to electric boats. Running at 83% with 15kW output you need to get rid of 2.5kW of heat into the air -- which is a tough challenge for a couple of hours or more on the Trent or the Ribble Link -- as opposed to 1kW into the water at 93%, which is dead easy. I know which I'd rather be on top of under those circumstances... 😉

 

(as you say, cruising at 3kW there's little difference, both solutions are maybe 92% and only have to get rid of 250W so no problem)

 

I keep asking but you keep not answering -- how far are you away from the motor on your wideboat? If you're some distance away up in a wheelhouse then you'll hear far less noise (from motor/belt/blower) than somebody on a narrowboat right on top of it, which is what most people are interested in. If you can just hear it from where you are, this could well be quite annoying on a narrowboat...

 

As I keep saying, it's a tradeoff between cost and heat/power/noise, there isn't one right answer -- your solution suits you (and it's cheaper, hotter and noisier), mine suits me (and it's more expensive, cooler and quieter). You pays (or saves...) your money and you takes your choice... 😉

 

(and the Waterworld solution is somewhere in between on all counts, which is the answer I was trying to give to the question asked)

As I said in the first place mine is a different motor to the one you have listed, how different it is is in details mine is a R so its much tougher and spins faster than the D 135 you have listed,  Cedric is hoping to have a 155 for me later this year, which is a 12 brush model and is substantially more powerful, nearly double the D135R that I have.

James on the Thames has one in his 70 x 13.6 widebeam it copes easily all day with the tidal Thames. Prior to the 155 he had 2 D135 Rs that performed ok but not as good as the 155.

As for distance from the motor I am probably slightly more distant than a narrowboat, 

[IanD]

1 hour ago, peterboat said:

As I said in the first place mine is a different motor to the one you have listed, how different it is is in details mine is a R so its much tougher and spins faster than the D 135 you have listed,  Cedric is hoping to have a 155 for me later this year, which is a 12 brush model and is substantially more powerful, nearly double the D135R that I have.

James on the Thames has one in his 70 x 13.6 widebeam it copes easily all day with the tidal Thames. Prior to the 155 he had 2 D135 Rs that performed ok but not as good as the 155.

As for distance from the motor I am probably slightly more distant than a narrowboat, 

Power and speed and toughness and "coping all day with the tidal Thames" are nothing to do with efficiency, you're just trying to distract again.

 

You claimed that the Lynch DC motor and controller are as efficient as a PMAC one but have provided no data to back this up -- and it's not the first (or seond, or third, or...) time you've done this sort of thing, claiming something that doesn't stack up and then trying to wriggle out of it when challenged... 😉

 

 

Edited July 27, 2022 by IanD

[jupiter1124]

On 25/07/2022 at 17:10, IanD said:

the thing wot makes to prop go round -- must be an electric motor. They don't say anything about where the power to do this originally comes from, which is why I gave a stupidly long list...

 

This may or may not be logical, but it's what the rules say

Even though diesel-electric / series hybrid still gets motive energy from diesel, I still tend to think that it is logical actually, even with zero solar and never shore power.

 

a) because I am absolutely convinced that this means of propulsion is more efficient given that boats operate at such slow speeds and are frequently idling in locks and such, 

 

b) for most boaters, at least liveabards like myself, the majority of engine use is for domestic purposes (electricity and water heating), and a generator will do this far more efficiently than a propulsion engine.

 

c) its not perfect but it is a step towards the all-electric vision of the future. Incentivising consumers and therefore manufacturers to early-adopt and develop electric motors and the associated systems gets us closer to the vision. There is little point in incentivising electric boats once the technology has "made it" and people will choose electric by default.

 

 

23 hours ago, IanD said:

Motors in pods sound attractive but these are targeted at the yacht market and are *extremely* expensive, they make even the BellMarine solution above (which came to about £12k IIRC) look cheap.

Why? This doesn't make sense. The worldwide yacht market is much bigger than the canal boat one. Are yacht engines much more powerful and don't translate to canal boats? Seems to me that a motor in a pod would benefit greatly from not needing mounting, stern gland and associated maintenance, extremely easy to install and retrofit, can be easily removed for maintenance, result in better handling due to directional thrust, leave space in the hull (maybe for the genny) and most of all once the whole motor is immersed in coolant I would think that expensive and complex cooling systems become redundant and perhaps even would confer efficiency advantages.

 

Is the challenge simply in waterproofing the motor?
is there maybe a huge gap in the market for "replacement tiller/rudder assemblies" that can allow switching out for an electric motor?

 

[IanD]

46 minutes ago, jupiter1124 said:

Even though diesel-electric / series hybrid still gets motive energy from diesel, I still tend to think that it is logical actually, even with zero solar and never shore power.

 

a) because I am absolutely convinced that this means of propulsion is more efficient given that boats operate at such slow speeds and are frequently idling in locks and such, 

 

b) for most boaters, at least liveabards like myself, the majority of engine use is for domestic purposes (electricity and water heating), and a generator will do this far more efficiently than a propulsion engine.

 

c) its not perfect but it is a step towards the all-electric vision of the future. Incentivising consumers and therefore manufacturers to early-adopt and develop electric motors and the associated systems gets us closer to the vision. There is little point in incentivising electric boats once the technology has "made it" and people will choose electric by default.

 

 

Why? This doesn't make sense. The worldwide yacht market is much bigger than the canal boat one. Are yacht engines much more powerful and don't translate to canal boats? Seems to me that a motor in a pod would benefit greatly from not needing mounting, stern gland and associated maintenance, extremely easy to install and retrofit, can be easily removed for maintenance, result in better handling due to directional thrust, leave space in the hull (maybe for the genny) and most of all once the whole motor is immersed in coolant I would think that expensive and complex cooling systems become redundant and perhaps even would confer efficiency advantages.

 

Is the challenge simply in waterproofing the motor?
is there maybe a huge gap in the market for "replacement tiller/rudder assemblies" that can allow switching out for an electric motor?

 

I agree 100% with your first few points, which is why series hybrids are increasing in popularity -- at least, among those fortunate enough to be able to afford them... 😉

 

All equipment for yachts tends to be expensive for several reasons; one is the amount of work needed to get it to pass various worldwide qualification standards, but a simpler reason (warning -- generalisation follows!) is that yacht owners see their hobby as expensive and are both richer and willing to pay more for stuff than penny-pinching narrowboaters 🙂

There's also the general fact that new technology made in small volumes is always more expensive than old technology made in big volumes, and even on the yacht market pod propulsion is a tiny part of the market -- and electric pod propulsion an even tinier part of an even smaller market. I looked at all this when I was investigating hybrid propulsion systems, and a 15kW Azipod or similar (plus controller/display etc.) was *horrendously* expensive, getting on for £20k IIRC just for the drive system.

 

In comparison (all 48V systems capable of 15kW continuous output) the Bell Marine motor plus all the bits needed to make it work was about £12k, the Lynch twin-motor one was (surprisingly!) something over £8k, the Waterworld one was £7.5k, and the Voltsport one was £4k -- but this was just for the basic motor/controller components, they didn't do the "kit" then and I guess this would be significantly more expensive -- but probably still cheaper than the others, as well as being one of the best-performing solutions. Which was why I was going to got that way until I decided to let Finesse deal with it all -- and their system is based on similar components...

 

Which kind of shoots Peter's claim that Lynch are cheap in the foot -- maybe they are if you just buy a single bare motor (which probably can't sustain the power needed, at least not at 48V) and engineer all the mounting parts and pulleys/belts yourself, and put your own control system together, but I don't think most people can (or want to) do this, they want something which can be installed with a similar level of difficulty to a diesel engine/gearbox. That's the apples-to-apples comparison with the prices above, but note that this is just the cost for the drive system, it doesn't include the other more expensive bits like batteries, inverter and generator which is what really pushes the total cost up.

 

I'm sure Peter will come back and say it ain't so and his system works for him and cost less than a box of cornflakes, but I know that there are a couple of big gotchas with his solution. The first is that he runs at 72V, which no drive supplier is going to do because this is above the low-voltage range and puts a huge extra safety burden on the design and manufacture -- which Peter can ignore, because if he electrocutes himself (however unlikely it is) it's his problem. But if this happens to any boater from a commercially supplied drive system which is not properly safety qualified (expensive) they can sue the socks off them, which is why almost all suppliers won't take this risk (or go through the safety certification hassle) and they're all 48V -- the same applies to the inverter/chargers and batteries.

 

The second is that as far as I can tell none of the single Lynch motors can sustain 15kW for at least 2 hours -- preferably more -- which is becoming accepted as the industry norm for a "go-anywhere" narrowboat, meaning one that can pass the Ribble Link or go up rivers like the Trent against strong currents -- and no amount of claiming "my mate's boat is fine on the Thames" changes this, pootling up the Thames is *far* less stressful. The last thing you want to happen is for the motor or controller to overheat after maybe half an hour going upstream and either reduce power or even worse cut out, because by then you're committed. Hope you have a good anchor and know how to use it... 😉

 

This is why the 48V Lynch boat systems that I posted use two motors -- and two controllers -- to be able to deliver these levels of power continuously. A single motor can easily deliver short-term power well above this which is fine for cars and bikes, but not for boats. The same is actually true for quite a lot of the cheaper "electric boat" solutions on the market using cheap belt-driven motors (e.g. Motenergy) sourced from China, the peak power is high but the continuous power is not. But they *are* cheap -- in fact cheaper than UK-built Lynch motors, which is probably why Hybrid Marine now use them (water-cooled) instead of the Lynch motors they used to use in their parallel hybrids...

Edited July 28, 2022 by IanD

[dmr]

41 minutes ago, jupiter1124 said:

Even though diesel-electric / series hybrid still gets motive energy from diesel, I still tend to think that it is logical actually, even with zero solar and never shore power.

 

a) because I am absolutely convinced that this means of propulsion is more efficient given that boats operate at such slow speeds and are frequently idling in locks and such, 

 

b) for most boaters, at least liveabards like myself, the majority of engine use is for domestic purposes (electricity and water heating), and a generator will do this far more efficiently than a propulsion engine.

 

c) its not perfect but it is a step towards the all-electric vision of the future. Incentivising consumers and therefore manufacturers to early-adopt and develop electric motors and the associated systems gets us closer to the vision. There is little point in incentivising electric boats once the technology has "made it" and people will choose electric by default.

 

 

Why? This doesn't make sense. The worldwide yacht market is much bigger than the canal boat one. Are yacht engines much more powerful and don't translate to canal boats? Seems to me that a motor in a pod would benefit greatly from not needing mounting, stern gland and associated maintenance, extremely easy to install and retrofit, can be easily removed for maintenance, result in better handling due to directional thrust, leave space in the hull (maybe for the genny) and most of all once the whole motor is immersed in coolant I would think that expensive and complex cooling systems become redundant and perhaps even would confer efficiency advantages.

 

Is the challenge simply in waterproofing the motor?
is there maybe a huge gap in the market for "replacement tiller/rudder assemblies" that can allow switching out for an electric motor?

 

 

Something similar has been done quite often in order to motorise a butty, but using a hydraulic rather than electric motor.

[dmr]

Im sticking with my big diesel and HVO for now, and not sure that I would be investing in an expensive new and electric boat just now. It does look like cycling and paddleboarding etc might be the future of the canals.  However I am keeping a close eye on all this electric stuff, amongst other things because I am, or was originally, an electrical/electronic engineer.

One thing that keeps hitting me is that 48volts really is too low for the powers involved and 72 or even 96volts would make a lot more sense. If it does all take off then hopefully somebody will do a commercial higher voltage system and get to grips with the regulations required.

A second observation is that all the available motors turn too fast and need a gearbox whilst direct drive should be a goal for any electrical system, though I confess that I like the sort of boats that have a prop speed that never goes much above 500rpm 😀

[MtB]

5 minutes ago, dmr said:

A second observation is that all the available motors turn too fast and need a gearbox whilst direct drive should be a goal for any electrical system

 

 

This always strikes me too. 

 

Similar issues crop up with electric bicycles in that the motor needs to deliver high torque at low speeds - in single numbers of revs per second in fact - a bikes seem to manage this ok so why not boats too? Would certainly help get rid of that annoying whine electric boats seem to have! 

 

Similar issues occured in reverse on bikes decades ago, when posh expensive bikes had hub dynamos to work the lights. VERY slow revving but still produced the energy. Possibly similar with big windmills too, although I suspect they have gearboxes to multiply up the RPM of the blades. 

[dmr]

4 minutes ago, MtB said:

 

 

This always strikes me too. 

 

Similar issues crop up with electric bicycles in that the motor needs to deliver high torque at low speeds - in single numbers of revs per second in fact - a bikes seem to manage this ok so why not boats too? Would certainly help get rid of that annoying whine electric boats seem to have! 

 

Similar issues occured in reverse on bikes decades ago, when posh expensive bikes had hub dynamos to work the lights. VERY slow revving but still produced the energy. Possibly similar with big windmills too, although I suspect they have gearboxes to multiply up the RPM of the blades. 

 

I think one issue with boats is that higher voltages are needed to get the power and in general higher voltages go hand in hand with higher speeds. Electric motors are much the same as diesels in some respects, the easiest way to get more power is to increase the speed, and to get high torque at low speeds requires a big motor.

[IanD]

1 hour ago, dmr said:

Im sticking with my big diesel and HVO for now, and not sure that I would be investing in an expensive new and electric boat just now. It does look like cycling and paddleboarding etc might be the future of the canals.  However I am keeping a close eye on all this electric stuff, amongst other things because I am, or was originally, an electrical/electronic engineer.

One thing that keeps hitting me is that 48volts really is too low for the powers involved and 72 or even 96volts would make a lot more sense. If it does all take off then hopefully somebody will do a commercial higher voltage system and get to grips with the regulations required.

A second observation is that all the available motors turn too fast and need a gearbox whilst direct drive should be a goal for any electrical system, though I confess that I like the sort of boats that have a prop speed that never goes much above 500rpm 😀

 

48V isn't too low for the powers involved, all the components needed (motors, controllers, contactors, inverter/chargers, batteries, MPPT controllers) are easily available from multiple sources and at reasonable cost. Higher-voltage gear is much thinner on the ground and more expensive, and is unlikely to be developed for these kinds of power levels -- for much higher power levels (bigger boats, EVs) 48V is too low so they use 400V, and the propulsion system cost is much higher anyway.

 

Market size *does* matter -- for example I'm fitting a 48V Vetus BOWPRO thruster (yeah, I know...) to avoid needing big batteries in the bow locker, and it only needs 25mm2 cable to run from the battery bank in the stern. Since they use a PMAC motor you'd think the 48V one would be cheaper than the 24V and 12V ones because the currents are lower and they're cheaper to build (like 48V inverters compared to 24V and 12V) -- but actually the 48V ones are *more* expensive. When asked about this Vetus replied that it was because they made and sold far more 12V/24V ones than the new 48V ones -- annoying, but understandable... 😞

 

Many of the motors do run too fast to be ideal for direct drive, given the power levels you end up with an "egg-whisk" prop -- for example for 15kW/1500rpm (Waterworld) the Vicprop calculator gives a tiny 14.3" x 8.4". This also goes well above the recommended ~1000rpm maximum prop speed for slow boats, so will be noisy and lead to a lot of watery thrashing around...

 

There are direct-drive motors which are much better, for example the Engiro 12013 is 15kW/1080rpm, giving 17.4" x 11.6" which is pretty much identical to the standard prop on a Beta 43. The downside is that the motor alone costs over £3000 and weighs 47kg, because it's basically a 31kW/96V/2180rpm motor running at half the voltage.

 

If you want an even lower prop speed (e.g. 500rpm) then the motor has to be geared (whine...), and a *much* bigger prop is needed (e.g. 27.7" x 25.1") which won't fit modern shallower-drafted hulls... 😉

Edited July 28, 2022 by IanD

[MtB]

4 minutes ago, dmr said:

 

I think one issue with boats is that higher voltages are needed to get the power and in general higher voltages go hand in hand with higher speeds. Electric motors are much the same as diesels in some respects, the easiest way to get more power is to increase the speed, and to get high torque at low speeds requires a big motor.

 

 

Yes higher voltages, higher speeds or higher currents or any combination thereof.

 

If going for low voltage and low speed one therefore ends up with high (very high!) current which = physically bigger everything + MUCH fatter conductors = big engineering much of it made of expensive copper.

 

But you know this obviously.

 

 

 

[IanD]

46 minutes ago, dmr said:

 

I think one issue with boats is that higher voltages are needed to get the power and in general higher voltages go hand in hand with higher speeds. Electric motors are much the same as diesels in some respects, the easiest way to get more power is to increase the speed, and to get high torque at low speeds requires a big motor.

 

You *don't* need high torque at low speeds to drive a prop, in the sense that maximum torque is at maximum rpm. But if you want the prop to turn more slowly at maximum power (see above) you do need a bigger (and more expensive) motor -- however PMAC motor cost is independent of voltage, it's the required power/torque/rpm that matters, you just need different stator windings for different voltages. For example, if you start with a 48V 15kW motor (158A) and rewind with more turns of thinner wire you can have a 96V 15kW motor (79A) at the same cost.

 

Unless fewer people want the higher voltage motors, in which case they will cost more... 😉

Edited July 28, 2022 by IanD

[MtB]

Like this perhaps:

 

 

 

[IanD]

9 minutes ago, MtB said:

 

 

Yes higher voltages, higher speeds or higher currents or any combination thereof.

 

If going for low voltage and low speed one therefore ends up with high (very high!) current which = physically bigger everything + MUCH fatter conductors = big engineering much of it made of expensive copper.

 

But you know this obviously.

 

 

Absolutely true *outside* the motor (inverter, cables) -- but not *inside*. Same amount of copper is needed for a higher voltage PMAC motor, just more turns of thinner wire (no commutator or brushes). It's what the manufacturers say if you ask them, and the data sheets show... 😉

 

And again, there's a lot of 48V kit (e.g. Victron) around at these power levels (up to 15kW or so) but almost none at higher voltages. If you move to higher power levels like 100kW or more (EVs, big boats) then the picture changes, and all the kit is 400V DC -- because once you go above 48V, you might as well go much higher to push the cost and cabling size down.

Edited July 28, 2022 by IanD

[David Mack]

1 hour ago, jupiter1124 said:

Is the challenge simply in waterproofing the motor?

One of the problems of a pod motor is that when running it will get warm - even with the cooling effect of being immersed in water. This results in the air inside the motor expanding, and then contracting again when the motor cools down after use.  Its asking a lot of the gland seal around the prop shaft not to allow some leakage of air out as it heats up, with water ingress as it cools. Water in the motor is not going to be good for reliability and longevity!

 

[Alan de Enfield]

5 minutes ago, David Mack said:

Its asking a lot of the gland seal around the prop shaft not to allow some leakage of air out as it heats up, with water ingress as it cools.

 

Exactly the same as with trailer boats - the wheel bearings get warm whilst you are towing, immediately reverse the trailer into the cold water and the bearings go "sluuuurrrrrp" and suck the water in past the seals.

 

You need to wait for 30+ minutes to allow the bearings to cool otherwise the seal doesn't have a chance.

 

I have spent many unhappy happy hours waiting on the motorway hard shoulder before learning :

 

1) Let bearings cool before launch, or

2) Change from launch bearings to road bearings before setting off for home, and,

3) Carry spare sets of bearings, grease etc with you.

[dmr]

1 hour ago, MtB said:

Like this perhaps:

 

 

 

 

Lovely, I have said before that this sort of thing would make a reasonable substitute for a big vintage diesel in a "trad trad" boat. I want one.

[dmr]

1 hour ago, IanD said:

 

You *don't* need high torque at low speeds to drive a prop, in the sense that maximum torque is at maximum rpm. But if you want the prop to turn more slowly at maximum power (see above) you do need a bigger (and more expensive) motor -- however PMAC motor cost is independent of voltage, it's the required power/torque/rpm that matters, you just need different stator windings for different voltages. For example, if you start with a 48V 15kW motor (158A) and rewind with more turns of thinner wire you can have a 96V 15kW motor (79A) at the same cost.

 

Unless fewer people want the higher voltage motors, in which case they will cost more... 😉

 

Sorry, and yes, I am aware of "prop law", in fact I get quite irritated by the electric motor advocates who keep boasting that an electric motor can produce full torque at zero speed. When I say high torque at low speed I am thinking in terms of about 30 horsepower at about 500rpm which is what most "trad trad" boats need.

 

I also get irritated by the statements that a 10kW electric motor is equivalent to a 60horsepower diesel, though maybe I have exaggerating just a little here. 😀

 

My concern about 48volt motors is that I don't like big currents. 30 horsepower is about 23kW and thats about  480 amps, and thats too many.

 

But don't listen to me, I am a bit of a dinosaur in boating terms as I have zero interest in gliding along the canals in silence, I like engines.

And if I do fancy a bit of silence then I go and sit at the front whilst my wife drives. 😀

[IanD]

42 minutes ago, dmr said:

 

Sorry, and yes, I am aware of "prop law", in fact I get quite irritated by the electric motor advocates who keep boasting that an electric motor can produce full torque at zero speed. When I say high torque at low speed I am thinking in terms of about 30 horsepower at about 500rpm which is what most "trad trad" boats need.

 

I also get irritated by the statements that a 10kW electric motor is equivalent to a 60horsepower diesel, though maybe I have exaggerating just a little here. 😀

 

My concern about 48volt motors is that I don't like big currents. 30 horsepower is about 23kW and thats about  480 amps, and thats too many.

 

But don't listen to me, I am a bit of a dinosaur in boating terms as I have zero interest in gliding along the canals in silence, I like engines.

And if I do fancy a bit of silence then I go and sit at the front whilst my wife drives. 😀

 

Agree with your first two comments, it annoys me too... 😉

 

(but 30hp at 500rpm needs a *massive* prop (30" x 28"?) -- lovely if it will fit on your boat, and you don't mind dredging the canals for everyone else...)

 

48V is a bit of a pain when you get above 15kW, but mainly because of the controllers, the batteries and (short!) cables are happy enough. The workable next solution up is a 30kW/40hp 6-phase motor using 2 controllers, which is exactly what Engiro do -- each of the controllers (and cabling) is identical to the 15kW one, LFP batteries are perfectly happy providing huge currents. Anything above this gets difficult, but isn't needed on the canal system even if you venture out onto rivers.

 

Nothing wrong with you liking big slow old diesels, I like the sound too (though not as much as a Bolinder) but preferably on somebody else's boat. *Especially* a Bolinder... 😉

Edited July 28, 2022 by IanD