Electric Boats

[peterboat]

2 hours ago, IanD said:

The reason you need shear pins with a diesel is there's a big heavy flywheel rotating at typically 2x prop speed, meaning it needs maybe 10x the force to stop it that the prop does. With a direct drive electric it's the other way round, the inertia of the motor is much smaller than the prop, about 5x IIRC when I worked the numbers out.

 

So the force on the coupling in a jam is maybe 50x smaller than with a diesel; stop the prop and the motor just stops too. Ironically your geared motor is worse, with a 3:1 gear ratio the motor needs 9x more force to stop it -- so your belt will very likely break.

 

A modern speed controller will just current limit at the programmed peak current and then ramp this down since the motor is stalled, no damage caused.

 

It really *is* basic mechanics, at least according the the course I did at uni 😉

Now think of what happens when a DC motor jams with brushes etc, its still being fed own from its speed controller wonder how long its brushes and armature would last?

[IanD]

9 hours ago, peterboat said:

Now think of what happens when a DC motor jams with brushes etc, its still being fed own from its speed controller wonder how long its brushes and armature would last?

Most of the motors used in boats nowadays are brushless PMAC, but IIRC your Lynch is old style brushed DC. With a current limit and rpm/temperature sensing in the PMAC controller (again, common nowadays) a locked rotor will cause no damage at all. This may not be the case with your setup, depending on the controller...

Edited August 22, 2021 by IanD

[peterboat]

Just now, IanD said:

Most of the motors used in boats nowadays are brushless PMAC, but IIRC your Lynch is a brushless DC. With a current limit and rpm/temperature sensing in the controller (again, common nowadays) a locked rotor will cause no damage at all. This may not be the case with your setup, depending on the controller...

Brushed Ian all Lynch motors are. They have been putting them in boats for 20 years, nearly always geared unless its a small lightweight boat.

At full bore I am putting 400 amps through the motor, I think a jam would produce the magic smoke in seconds, the belt will no doubt snap and save the day

 

[IanD]

8 hours ago, peterboat said:

Brushed Ian all Lynch motors are. They have been putting them in boats for 20 years, nearly always geared unless its a small lightweight boat.

At full bore I am putting 400 amps through the motor, I think a jam would produce the magic smoke in seconds, the belt will no doubt snap and save the day

 

Brushed is what I meant. Old tech controllers and motors don't like being jammed, modern ones don't care 😉

[tehmarks]

On 21/08/2021 at 13:01, Detling said:

That power can be useful stopping sharply

 

That is cunning indeed. Ending up sideways across the cut so that they ram you. Genius!

 

On 21/08/2021 at 13:01, Detling said:

Also used for reversing the boat off the sticky bottom the bow has slid silently onto and is now preventing forward progress. 

 

Also good for making lots of noise and sploshing lots of silty water about as your stern buries itself deeper in the water and onto the aforementioned sticky bottom, eliminating all danger of movement (and happily thus also of ramming).

 

[IanD]

I spent a lot of time earlier in this thread (and others) arguing that power consumption at "normal" canal cruising speed for an electric boat was around 3kW, and various electric boat fans argued that this was far too high and I was overestimating this -- and also the required motor power in an electric boat.

 

My reply was that to get the kind of very low numbers quoted by some (e.g. Mothership Marine, narrowboat "Shine", peterboat...) they must be going more slowly than "normal" cruising speed, which I took be be a bit less than 3mph on a normal canal, but this was disputed.

 

Finally got round to reading the Ortomarine test results now they've been released, which are very interesting -- and there's one particularly interesting graph showing canal speed vs. power consumption.

 

https://www.ortomarine.co.uk/wp-content/uploads/2021/10/Ortomarine-Narrowboat-Trial-Final-Report.pdf

 

Several of the boats fall exactly on the line which shows that power in kW is 0.133*mph^3, so 3kW gives 2.8mph, which is certainly "normal" cruising speed (on a diesel boat) from measurements by myself and various other people.

 

It also shows that by slowing down to about 2mph the power drops to about 1kW, which is presumably what "Shine" was doing to get their much-vaunted low power consumption numbers. Absolutely no problem if that's what you want to do, but it's just showing that if you go slower you use a lot less power, there's no "magic bullet" that lets an electric boat travel at 3mph on 1kW as was claimed...

[ditchcrawler]

I met one of these electric boats in the summer with their stick on solar panels and got chatting mainly about the panels as they are stick down ones and temperature v performance, The owner thought that the temperature would need to be very high to effect the output and the odd bucket of canal water would fix it, more interesting they said that running in a balanced condition, ie, no power from the batteries they would be traveling slower than lots of boats on tickover. As I see it unless we see an infrastructure of charging point, people only travel for a few hours on  long sunny days we are still relying of generators to supply the power. I don't know if any have read this? I find the font a pain 

 

EFOY Pro Fuel Cell (Real World Thoughts and Usage Statistics on a Narrowboat) - A Family Adventure aboard NB EMMELINE (hensby-peck.co.uk)

[Tony Brooks]

9 minutes ago, ditchcrawler said:

I met one of these electric boats in the summer with their stick on solar panels and got chatting mainly about the panels as they are stick down ones and temperature v performance, The owner thought that the temperature would need to be very high to effect the output and the odd bucket of canal water would fix it, more interesting they said that running in a balanced condition, ie, no power from the batteries they would be traveling slower than lots of boats on tickover. As I see it unless we see an infrastructure of charging point, people only travel for a few hours on  long sunny days we are still relying of generators to supply the power. I don't know if any have read this? I find the font a pain 

 

EFOY Pro Fuel Cell (Real World Thoughts and Usage Statistics on a Narrowboat) - A Family Adventure aboard NB EMMELINE (hensby-peck.co.uk)

 

I agree about the font. I think Efoy cells use ethanol and it is supposed to be very pure to prevent poisoning the pile. I dread to think what the running cost would be (I did look into Efoy cells about 15 years ago).

 

In reply to IanD:

 

Those graphs are to be expected and confirm your supposition. The water or wind resistance increases to the square of speed so however "slippy" the hull or efficient the motor is the graph will always be a similar shape.

[IanD]

9 minutes ago, Tony Brooks said:

 

I agree about the font. I think Efoy cells use ethanol and it is supposed to be very pure to prevent poisoning the pile. I dread to think what the running cost would be (I did look into Efoy cells about 15 years ago).

 

In reply to IanD:

 

Those graphs are to be expected and confirm your supposition. The water or wind resistance increases to the square of speed so however "slippy" the hull or efficient the motor is the graph will always be a similar shape.

I understand why the graph is the shape it is, power goes up as the cube of speed...

25 minutes ago, ditchcrawler said:

I met one of these electric boats in the summer with their stick on solar panels and got chatting mainly about the panels as they are stick down ones and temperature v performance, The owner thought that the temperature would need to be very high to effect the output and the odd bucket of canal water would fix it, more interesting they said that running in a balanced condition, ie, no power from the batteries they would be traveling slower than lots of boats on tickover. As I see it unless we see an infrastructure of charging point, people only travel for a few hours on  long sunny days we are still relying of generators to supply the power. I don't know if any have read this? I find the font a pain 

 

EFOY Pro Fuel Cell (Real World Thoughts and Usage Statistics on a Narrowboat) - A Family Adventure aboard NB EMMELINE (hensby-peck.co.uk)

Solar cells lose a few percent (single digit number, typically 5%) when they get hot, not enough to make a big difference. Flat mounting instead of optimum south-facing tilt (difficult on a narrowboat) loses about 15%.

[peterboat]

My 3.3kws at 3mph in deep water is normal then for my boat. I learned a while ago that you can't rely on sat nav distance over time is more accurate. 

If I was starting from scratch I would go for a 72 foot trad with engine room for the genny motor and batteries and a full roof of solar panels. It would also be as shallow as possible on the draught 

[zenataomm]

On 15/11/2020 at 16:49, Tractor said:

 .......... neckerchiefs and flat caps all round?

Research first always! 

Trilby!!

[David Mack]

1 hour ago, peterboat said:

If I was starting from scratch I would go for a 72 foot trad with engine room for the genny motor and batteries and a full roof of solar panels. It would also be as shallow as possible on the draught 

 But you need to be able to fit a large enough prop to start and stop a full length boat, and if you want a reasonable battery capacity and range then you are already carrying a fair bit of weight. I do wonder if, having done the sums, you would end up with something any shallower than a typical modern diesel powered boat of the same length.

[peterboat]

22 minutes ago, David Mack said:

 But you need to be able to fit a large enough prop to start and stop a full length boat, and if you want a reasonable battery capacity and range then you are already carrying a fair bit of weight. I do wonder if, having done the sums, you would end up with something any shallower than a typical modern diesel powered boat of the same length.

You have to read the article, also having done the conversion on my own widebeam I know it's a lot lighter than the diesel engine that's after fitting a genny as well. Given that mostly I am going forward drag from draught is the enemy of power usage.

I would like an engine room so weight would be further forward as well so that should help 

[Jen-in-Wellies]

5 hours ago, IanD said:

Finally got round to reading the Ortomarine test results now they've been released, which are very interesting -- and there's one particularly interesting graph showing canal speed vs. power consumption.

This trial took in a variety of waterways, from shallow canals, to the wide Severn at Worcester. I've not read the report yet. With diesel boats it is generally observed that going faster needs additional power on a shallow narrow canal than on a deep, wide waterway. The extra effort to force the water around and under the boat, followed perhaps by the stern digging in to the ooze on the bottom takes more effort and eventually no return on more power applied.

@peterboat cruises his electric boat on the wide and deep SSYN for the most part. Even the shallowest section up to Sheffield is still typically 4' or more deep in the channel. Could this influence the relatively low power consumption he reports for a given speed, compared with other inland boaters?

Jen

[dmr]

Have a look at this:

 

https://nb-firecrest.co.uk/tag/power-curve/

 

They might even be or have been forum members?  I sort of trust this data because they are not trying to sell anything, and it fits in fairly well with the data above. Not sure how deep the boat is.

[peterboat]

13 hours ago, Jen-in-Wellies said:

This trial took in a variety of waterways, from shallow canals, to the wide Severn at Worcester. I've not read the report yet. With diesel boats it is generally observed that going faster needs additional power on a shallow narrow canal than on a deep, wide waterway. The extra effort to force the water around and under the boat, followed perhaps by the stern digging in to the ooze on the bottom takes more effort and eventually no return on more power applied.

@peterboat cruises his electric boat on the wide and deep SSYN for the most part. Even the shallowest section up to Sheffield is still typically 4' or more deep in the channel. Could this influence the relatively low power consumption he reports for a given speed, compared with other inland boaters?

Jen

You are right Jen its mostly 50 plus wide and 10 foot deep because of Exol Pride, coming to Sheffield uses little power due to all the locks 😊

[Murflynn]

15 hours ago, peterboat said:

You have to read the article, also having done the conversion on my own widebeam I know it's a lot lighter than the diesel engine that's after fitting a genny as well. Given that mostly I am going forward drag from draught is the enemy of power usage.

I would like an engine room so weight would be further forward as well so that should help 

drag from draught?  I assume you are referring to the drag related to the displacement of water while moving through relatively shallow (and narrow in many cases) water rather than surface friction. 

I don't believe that a well-designed pencil shaped hull moving in deep water (where surface area / friction drag is the main component) will be significantly slower that a similar but more shallow hull (at typical canal speeds), and the directional stability will be better.

 

PS  ...............  I've just seen your reply to Jen - confirming the drag displacement factor.

Edited November 7, 2021 by Murflynn

[peterboat]

14 minutes ago, Murflynn said:

drag from draught?  I assume you are referring to the drag related to the displacement of water while moving through relatively shallow (and narrow in many cases) water rather than surface friction. 

I don't believe that a well-designed pencil shaped hull moving in deep water (where surface area / friction drag is the main component) will be significantly slower that a similar but more shallow hull (at typical canal speeds), and the directional stability will be better.

 

PS  ...............  I've just seen your reply to Jen - confirming the drag displacement factor.

When I went to Thorne last, the canal is significantly shallower than the one I cruise on, the speed drops for the same power, it's one of the advantages of having an accurate method of knowing how much power you are using, both in KWs or amps, what I really want is a good at slow speed sat nav though. 

If I was building a narrowboat, I would go for long waterline length, plus a shallow as possible draught to avoid bottom drag on shallow canals, it might even be worth making it of thinner steel on top sides to make it more stable along with say a 15mm bottom?

[IanD]

19 hours ago, Jen-in-Wellies said:

This trial took in a variety of waterways, from shallow canals, to the wide Severn at Worcester. I've not read the report yet. With diesel boats it is generally observed that going faster needs additional power on a shallow narrow canal than on a deep, wide waterway. The extra effort to force the water around and under the boat, followed perhaps by the stern digging in to the ooze on the bottom takes more effort and eventually no return on more power applied.

@peterboat cruises his electric boat on the wide and deep SSYN for the most part. Even the shallowest section up to Sheffield is still typically 4' or more deep in the channel. Could this influence the relatively low power consumption he reports for a given speed, compared with other inland boaters?

Jen

 

That's correct for Peter (as he acknowledges), and also the published review of Shine was on rivers where the water is deep. But implying that this is true for most canals in the UK which are shallower and narrower (like the one the test results were for) is misleading at best, especially if you're trying to sell electric boats based on "it only needs 1kW when cruising, and you can do all this on solar power alone" which is what a certain company is doing and whose owner flounced off this forum when told that his claims were dodgy.

 

It's like car manufacturers selling hybrid cars using their ludicrously good official mpg/CO2 figures, which they very rarely get anywhere close to in real life because of the short range (typically 30m or so -- and this is "on test" not in real life, so actually even less than this) on battery power. The manufacturers know this, but they hide behind the letter of the law which is the "official" figures, sometimes with a bit in the small print which says that the test figures may not predict real life mpg... 😉

 

When doing a power audit to decide on things like battery size, if you assume that an electric narrowboat on the canals will consume 3kW when cruising at normal speed, 1kW when passing moored boats, and 0kW in locks, you won't be far out.

[TNLI]

5 KW Brushless Sailboat Kit (thunderstruck-ev.com)

 

Looking very hard at that system with 48V, (4 sealed 12v Bosch batteries), but with my set of batteries and a 5-6 kW air cooled diesel gen set. I was looking at a 48V go kart motor, (36V if you don't like electrical fires), BUT they cost a grand without anything in the way of extras. This newish company seems good and they can arrange installation which is important if you want a guarantee or warranty to be valid. 

 

Anyone got their basic system fitted ??

[IanD]

16 minutes ago, TNLI said:

5 KW Brushless Sailboat Kit (thunderstruck-ev.com)

 

Looking very hard at that system with 48V, (4 sealed 12v Bosch batteries), but with my set of batteries and a 5-6 kW air cooled diesel gen set. I was looking at a 48V go kart motor, (36V if you don't like electrical fires), BUT they cost a grand without anything in the way of extras. This newish company seems good and they can arrange installation which is important if you want a guarantee or warranty to be valid. 

 

Anyone got their basic system fitted ??

 

You might be better going for something sold and supported in the UK which also includes belt-drive reduction, mounting hardware and thrust bearing, ready to install into a boat, like these:

 

https://www.voltsport.co.uk/Marine-Propulsion-Systems

[peterboat]

30 minutes ago, TNLI said:

5 KW Brushless Sailboat Kit (thunderstruck-ev.com)

 

Looking very hard at that system with 48V, (4 sealed 12v Bosch batteries), but with my set of batteries and a 5-6 kW air cooled diesel gen set. I was looking at a 48V go kart motor, (36V if you don't like electrical fires), BUT they cost a grand without anything in the way of extras. This newish company seems good and they can arrange installation which is important if you want a guarantee or warranty to be valid. 

 

Anyone got their basic system fitted ??

 

8 minutes ago, IanD said:

 

You might be better going for something sold and supported in the UK which also includes belt-drive reduction, mounting hardware and thrust bearing, ready to install into a boat, like these:

 

https://www.voltsport.co.uk/Marine-Propulsion-Systems

The kit seemed cheap, but you do have work to do to make it a working system, the stuff that Ian showed had no prices but seem more complete.

The sevcon controller is generally reliable I have a couple of them one is in use the other is a spare that I have not needed

[IanD]

4 hours ago, peterboat said:

 

The kit seemed cheap, but you do have work to do to make it a working system, the stuff that Ian showed had no prices but seem more complete.

The sevcon controller is generally reliable I have a couple of them one is in use the other is a spare that I have not needed

I got a quote from Voltsport for the direct drive system and it was surprisingly reasonable given the cost of the components. It would be interesting to find out how much the belt-drive systems cost, I would expect less because the motor is much cheaper. 

[john.k]

Ive had a good deal of experience of DC motors driving things.....think Coles diesel electric cranes........my self propelled yard crane has a 40 hp DC motor driving the wheels,and the motor (BTH) has proved indestructable these 60 years .......the drive motor can stall out ,as it did one time loading the crane onto a float with bent ramps......anyhoo,even after stalling repeated times,the commutator was just warm...another time the crane went through knee deep mud for hundreds of yard......motor wasnt even warm.....but its large /est 1 ton /for 40 hp rating............from new,the crane was driven on the road from job to job------Ive driven it on the road a few times.

[peterboat]

5 hours ago, john.k said:

Ive had a good deal of experience of DC motors driving things.....think Coles diesel electric cranes........my self propelled yard crane has a 40 hp DC motor driving the wheels,and the motor (BTH) has proved indestructable these 60 years .......the drive motor can stall out ,as it did one time loading the crane onto a float with bent ramps......anyhoo,even after stalling repeated times,the commutator was just warm...another time the crane went through knee deep mud for hundreds of yard......motor wasnt even warm.....but its large /est 1 ton /for 40 hp rating............from new,the crane was driven on the road from job to job------Ive driven it on the road a few times.

My boat has a DC motor