Electric?

[Murflynn]

6 minutes ago, IanD said:

 

No doubt there are plenty of people who mostly stay moored up and only cruise for a couple of hours at a time or every few days for who this might still work, at least in summer, thought they'd be stuck in winter. Anyone who wants to put in what I'd call a solid day of cruising -- either to get a fair distance from A to B, or with any significant time upriver, or most hire boats -- will probably be able to cruise for 1 day (assuming big enough batteries) but will then have to stop for 2 days to recharge.

 

 

 

so continuous moorers will have to manhaul their boats in winter.  can't be a bad thing - keep them fit.

[IanD]

Just now, Murflynn said:

so continuous moorers will have to manhaul their boats in winter.  can't be a bad thing - keep them fit.

Every cloud has a silver lining... ?

[Theo]

Only just read through this.  I note the absurdity of having a deisel generator on an electric boat.  The reason that some people consider it is to keep noise down.  You ahve the generator in the bow and run it when you are off the boat? or when you are less bothered about the noise.  Silent smoke free lock working might appeal.

 

N

[peterboat]

41 minutes ago, IanD said:

So let's do a power audit for a narrowboat...

 

A 57 foot boat would have a job getting more than 6 panels (1.8m x 1.2m) on the roof by the time you allow for hatches and roof fittings (and of course this means no plants, wood, canoes or anything else that many people like to keep on the roof) which is about 2kW rated power. The best-case yield data for solar in the UK is shown below:

 

 

This is about 7.5kWh/day for a 2kW system, but assumes perfectly angled unshaded south-facing panels, so let's assume 80% of this for a narrowboat which is typically 6kWh/day in summer and 1.5kWh/day in the depths of winter -- note that this means one of those big 6" x 4" panels only puts out 1kWh/day even in summer...

 

Peter's number of 1000W to propel a narrowboat on the narrow canals is way too optimistic compared to your widebeam boat in deep water, figures from electric/hybrid narrowboats suggest an average of about 3kW/hour into the batteries is needed to maintain charge when when cruising along at 3mph (less past moored boats, almost nothing in locks) -- allowing for inefficiencies in charging/discharging, motor and controller and belts, this corresponds to about 3hp at the prop.

 

So this suggests that in summer two days of charging will pay for one day of motoring, but this ignores the power needed to run everything else on the boat. Even for a very abstemious owner (just fridge and LED lights and a few low-power things like chargers, and the drain of a small inverter) I doubt that this would be less than 1.5kWh/day, which is only 60W averaged over 24h. So this leaves 4.5kWh per day (in summer) which will drive the boat for 90mins -- but this falls in spring and autumn (~60mins/day) and to zero in Jan/Dec (1.5kWh/day all used up) so you can't move for 2 months.

 

It's true that this is a lot longer past moored boats and waiting in locks, but also note that going upstream in a river (like I did on the Trent recently, or the Soar, or the Avon, or...) puts the power demand up a lot -- looking at typical revs I saw and working back to propeller load, I reckon the demand is around 9kW (~10hp at prop), at least doubling (~20hp at prop) if the river is fast-flowing but still open. This means 1 day of solar in summer will drive you up a river for 30mins, or 15mins if it's fast.

 

Yes you could get another couple of panels onto a full-length boat which will help, but equally 60W average is a very low power drain, you only have to do something for a few hours that uses power (TV, laptop) to double this which pushes the numbers back the other way, so I think these are reasonable guesses -- feel free to disagree, but you need to crunch the numbers.

 

So the end conclusion is that on a narrowboat one day of solar power typically lets you do the following:

 

Summer : cruise for 90mins at 3mph, 30mins up a river, 15mins if fast-flowing

Spring/autumn : cruise for 60mins at 3mph, 20mins up a river, 10mins if fast-flowing

Jan/Dec : stay moored up

 

(for a wideboat like Peter's with 5kW of solar these times are ~3x longer which is why it works for him)

 

No doubt there are plenty of people who mostly stay moored up and only cruise for a couple of hours at a time or every few days for who this might still work, at least in summer, thought they'd be stuck in winter. Anyone who wants to put in what I'd call a solid day of cruising -- either to get a fair distance from A to B, or with any significant time upriver, or most hire boats -- will probably be able to cruise for 1 day (assuming big enough batteries) but will then have to stop for 2 days to recharge.

 

So pretty much the entire narrowboat hire business on the canals (which pays a lot towards keeping the system going) would be killed -- all the routes like the rings (Cheshire, Four Counties, Stourport, Warwickshire...) which people now do in a week (6+ days travelling) would take 3 weeks.

 

Other than charge points round the system, the only way this would work for hire boats would be to fit *huge* battery banks -- a week's cruise would need ~80kWh usable so a ~100kWh battery, similar size to the biggest Tesla ones) with all the same consequences (massive cost because they *have* to be lithium, HV systems running at ~400V DC), with charging back at the base during turnaround so a boatyards of any size will need a hefty mains supply.

 

[BTW, I cross-checked all these power and energy use numbers back against typical diesel fuel consumption (and diesel fuel energy content and engine efficiency) and they stack up]

 

All of which comes back to the fact that electric boats and solar power look like a great idea, but for a lot of people (the majority? don't know how many are stayers/movers/hirers) and the entire hire boat industry the only way to make this work is charging points around the system -- the problem is simply that solar panels that will fit on a narrowboat in the UK can't keep up with energy demands for propulsion and onboard living, unless you spend most of the time (or all of it in winter...) stationary ?

As I said 1 KW for cruising, I suggest you read the link I am posting also using bifacial panels I think over 2 KW is possible on a 57 foot NB. When I was at crick last year I remember going on Shine and thinking it was a nice boat but could have done with more solar

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj15MO2qrHsAhX-SBUIHUJNAeIQFjAAegQIBBAC&url=http%3A%2F%2Fmothershipmarine.com%2Fnarrowboat%2F&usg=AOvVaw2u1g3uE2Hi4Rw6MpL-heD5

35 minutes ago, Mike Todd said:

Most so-called zero carbon solutions to boat energy are far from that as they utilise technology that currently displaces the carbon from the boat to on shore. In addition, solar panels and batteries are consuming rare resources at an alarming rate, so  much that the retrieval of quite tiny amounts from recycling is becoming economically viable. What they do have is a much better emission profile even if, again, some of that is by displacement.

 

I very much look forward to the day when energy production and consumption is much more compatible long term with the maintenance of our environment but this will only happen when total systems analyses are done, rather than local sub optimisations (look how good I am, no smoke - at least not visible here) In the end we cannot escape basic physics regarding entropy! 

I think you will discover that all of a lithium battery is recycled and has been for quiet a while same with solar panels

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi-1KnIrLHsAhUMYcAKHd2aBxoQFjAAegQIAxAC&url=https%3A%2F%2Fwww.greenmatch.co.uk%2Fblog%2F2017%2F10%2Fthe-opportunities-of-solar-panel-recycling&usg=AOvVaw0wxWPqPbmUPpgoFshaGMwq

Edited October 13, 2020 by peterboat

[IanD]

1 hour ago, peterboat said:

As I said 1 KW for cruising, I suggest you read the link I am posting also using bifacial panels I think over 2 KW is possible on a 57 foot NB. When I was at crick last year I remember going on Shine and thinking it was a nice boat but could have done with more solar

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj15MO2qrHsAhX-SBUIHUJNAeIQFjAAegQIBBAC&url=http%3A%2F%2Fmothershipmarine.com%2Fnarrowboat%2F&usg=AOvVaw2u1g3uE2Hi4Rw6MpL-heD5

I think you will discover that all of a lithium battery is recycled and has been for quiet a while same with solar panels

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi-1KnIrLHsAhUMYcAKHd2aBxoQFjAAegQIAxAC&url=https%3A%2F%2Fwww.greenmatch.co.uk%2Fblog%2F2017%2F10%2Fthe-opportunities-of-solar-panel-recycling&usg=AOvVaw0wxWPqPbmUPpgoFshaGMwq

Those numbers for Shine don't stack up with what other hybrid boat owners (and other manufacturers) say, or normal diesel power. They say 0.7kW-1kW "when passing moored boats at Crick" (which makes sense), but their figures for power "when cruising" seem very low when you consider that a Beta 43 (or any other diesel) at typical canal cruising rpm (around 3mph, normal canal, no breaking wash) puts about 4bhp/3kW into the prop (typically 1.5l/h diesel at about 20% efficiency). I suspect that when travelling they are what I'd call "creepers" (and want to sell their boats), and their numbers are averaged per hour and include passing moored boats and locks and are for short days -- and they have a backup generator...

 

(the Vicprop calculator gives 4.2mph on open water for a 57 foot narrowboat on 4bhp, which sounds right for 3mph on canals and stacks up with typical diesel consumption, so I can't see any way to make the Shine numbers add up -- Hybrid Marine UK also quote about 3kW IIRC, so all other sources says they're being "economical with the truth")

 

The numbers I gave were specifically for *cruising time at 3mph*, so people can add on time going more slowly and at locks -- even in a relatively long day (8 hours) you'd typically do (my guess) maybe 4 hours open canal cruising plus 1-2 hours past moored boats and 1-2 hours in locks, which drops the average use per day.

 

Bifacial panels (with a white or solar reflective paint roof underneath) boost power by about 25% (ideal case again...), so an extra 1.5kWh/day ("2.5kW" of panels instead of "2kW" -- data sheet numbers). This increases the 3mph cruising time for a day's solar from ~90mins in summer to ~120mins, worthwhile but not game-changing -- but at least it would also allow 30mins of travel in the winter.

 

All of which is still based on being extremely frugal with electricity usage onboard, which is fine some some (including you) but not for many. And you have 5kW of solar panels which is completely impossible on a narrowboat.

 

You have a system that works for you on a wideboat but won't for many on narrowboats, including all hire boats -- so though I admire your laudable evangelism about solar powered electric boats you should realise that just because it works for you doesn't mean it'll work for everyone else, in fact quite the opposite is true ?

Edited October 13, 2020 by IanD

[Murflynn]

I have to agree with Ian.  

My 600kg 20ft long and 3ft waterline beam canoe-bodied electric cruiser with a smooth hull that can be pulled into a lock by a 5 year old consumes 400W at 3mph (minimal wake and no transom turbulence). 

The hull speed factor V/(square root of L) in knots and feet is about 0.55 which of course is way below the speed at which wave-making becomes significant.

1000W for a full size narrowboat weighing 20 times that and with relatively rough blacking at the same speed seems highly unrealistic.

[peterboat]

40 minutes ago, IanD said:

Those numbers for Shine don't stack up with what other hybrid boat owners (and other manufacturers) say, or normal diesel power. They say 0.7kW-1kW "when passing moored boats at Crick" (which makes sense), but their figures for power "when cruising" seem very low when you consider that a Beta 43 (or any other diesel) at typical canal cruising rpm (around 3mph, normal canal, no breaking wash) puts about 4bhp/3kW into the prop (typically 1.5l/h diesel at about 20% efficiency). I suspect that when travelling they are what I'd call "creepers" (and want to sell their boats), and their numbers are averaged per hour and include passing moored boats and locks and are for short days -- and they have a backup generator...

 

(the Vicprop calculator gives 4.2mph on open water for a 57 foot narrowboat on 4bhp, which sounds right for 3mph on canals and stacks up with typical diesel consumption, so I can't see any way to make the Shine numbers add up -- Hybrid Marine UK also quote about 3kW IIRC, so all other sources says they're being "economical with the truth")

 

The numbers I gave were specifically for *cruising time at 3mph*, so people can add on time going more slowly and at locks -- even in a relatively long day (8 hours) you'd typically do (my guess) maybe 4 hours open canal cruising plus 1-2 hours past moored boats and 1-2 hours in locks, which drops the average use per day.

 

Bifacial panels (with a white or solar reflective paint roof underneath) boost power by about 25% (ideal case again...), so an extra 1.5kWh/day ("2.5kW" of panels instead of "2kW" -- data sheet numbers). This increases the 3mph cruising time for a day's solar from ~90mins in summer to ~120mins, worthwhile but not game-changing -- but at least it would also allow 30mins of travel in the winter.

 

All of which is still based on being extremely frugal with electricity usage onboard, which is fine some some (including you) but not for many. And you have 5kW of solar panels which is completely impossible on a narrowboat.

 

You have a system that works for you on a wideboat but won't for many on narrowboats, including all hire boats -- so though I admire your laudable evangelism about solar powered electric boats you should realise that just because it works for you doesn't mean it'll work for everyone else, in fact quite the opposite is true ?

The problem with hybrids is you are dragging the gearbox around as well, I was going this route with my old NB but discounted it for that reason 

 Its better by far to be electric motor large solar arrays and backup built in genny for the most part the genny would be redundant 

[Jen-in-Wellies]

So we are back to a proper electric charging post network for the system, or my idea of battery tow tractors on the tow path to get the propulsion power required down to less than 1hp (740W), which we know works as that is the power of one horse and could be charged from solar for normal narrowboat cruising in the summer without needing a charging post every day.

 

Jen

 

Edited October 13, 2020 by Jen-in-Wellies

[Mike Todd]

1 hour ago, peterboat said:

As I said 1 KW for cruising, I suggest you read the link I am posting also using bifacial panels I think over 2 KW is possible on a 57 foot NB. When I was at crick last year I remember going on Shine and thinking it was a nice boat but could have done with more solar

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj15MO2qrHsAhX-SBUIHUJNAeIQFjAAegQIBBAC&url=http%3A%2F%2Fmothershipmarine.com%2Fnarrowboat%2F&usg=AOvVaw2u1g3uE2Hi4Rw6MpL-heD5

I think you will discover that all of a lithium battery is recycled and has been for quiet a while same with solar panels

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi-1KnIrLHsAhUMYcAKHd2aBxoQFjAAegQIAxAC&url=https%3A%2F%2Fwww.greenmatch.co.uk%2Fblog%2F2017%2F10%2Fthe-opportunities-of-solar-panel-recycling&usg=AOvVaw0wxWPqPbmUPpgoFshaGMwq

My comment was about their construction not their disposal

[Momac]

4 hours ago, Jen-in-Wellies said:

..........install diesels 'cause they reckon the sound is warmer?

 

 

And so it is?

 

[peterboat]

54 minutes ago, Murflynn said:

I have to agree with Ian.  

My 600kg 20ft long and 3ft waterline beam canoe-bodied electric cruiser with a smooth hull that can be pulled into a lock by a 5 year old consumes 400W at 3mph (minimal wake and no transom turbulence). 

The hull speed factor V/(square root of L) in knots and feet is about 0.55 which of course is way below the speed at which wave-making becomes significant.

1000W for a full size narrowboat weighing 20 times that and with relatively rough blacking at the same speed seems highly unrealistic.

My bathtub uses little electric at 3 mph and thats 12 x 34 but it is a boaty boat shape. maybe Shine has smooth 2 pack? a boat up the moorings has a coloured 2 pack blacking that is shiny Trevor claims the boat goes better since its been done

49 minutes ago, Mike Todd said:

My comment was about their construction not their disposal

So oil and gas exploration and extraction cause no pollution? totally damage free?

Edited October 13, 2020 by peterboat

[Jen-in-Wellies]

24 minutes ago, peterboat said:

So oild and gas exploration and extraction cause no pollution? totally damage free?

I remember the old petrol station promotions. "Free Oil Covered Gannet With Every Five Gallons".

[peterboat]

Just now, Jen-in-Wellies said:

I remember the old petrol station promotions. "Free Oil Covered Gannet With Every Five Gallons".

Our canal was closed last week due to oil based pollution because EXOL had its boom down but it was to late! We had blue coloured swans and ducks paddling around in the filth and even now we have the RSPCA going up and down looking for dead/injured birds

[Jen-in-Wellies]

3 minutes ago, peterboat said:

Our canal was closed last week due to oil based pollution because EXOL had its boom down but it was to late! We had blue coloured swans and ducks paddling around in the filth and even now we have the RSPCA going up and down looking for dead/injured birds

I saw the CaRT navigation closure notice and did wonder if it was EXOL related. Sorry to hear that.

[peterboat]

3 minutes ago, Jen-in-Wellies said:

I saw the CaRT navigation closure notice and did wonder if it was EXOL related. Sorry to hear that.

Not as sorry as the blue swans and ducks ?

[IanD]

44 minutes ago, peterboat said:

My bathtub uses little electric at 3 mph and thats 12 x 34 but it is a boaty boat shape. maybe Shine has smooth 2 pack? a boat up the moorings has a coloured 2 pack blacking that is shiny Trevor claims the boat goes better since its been done

So oild and gas exploration and extraction cause no pollution? totally damage free?

It doesn't matter what magic paint is used, all the numbers from various reputable sources (except Shine) and the experience of people on this forum say you need about 4bhp/3kW for a narrowboat cruising in a normal canal (not deep water) at normal speed (not rushing) -- estimates from Hybrid Marine, Victron prop calculator, engine efficiency curves from Integrel together with numbers reported by many people of 1.5l/hr typical diesel fuel consumption and their cruising revs given prop size and prop law all agree.

 

The only way to use less power than this is to slow down or cruise at 3mph on a deep canal/lake/river, which is why the Vicprop calculator predicts 4.2mph on 4bhp (standard hull resistance curves in deep water, you're not going to convince anybody that these are wrong). Past moored boats power is probably halved, and it's nil while waiting for a lock. If Shine have included plenty of these when working out total energy use for a day's leisurely travel, divided this by total hours, and then quoted *average* power in kW used over the day then their numbers make a bit more sense. But implying that you can "cruise along" while drawing 1-1.5kW is simply not credible unless you cruise more slowly than normal, they're definitely being "economical with the truth" to make their electric boat look better/more practical than it really is ?

 

If their numbers are right, why does it need a backup generator? Solar alone should generate plenty of power for cruising...

Edited October 13, 2020 by IanD

[dmr]

3 hours ago, IanD said:

So let's do a power audit for an electric narrowboat using solar power...

 

 

 

Summer : cruise for 90mins at 3mph, 30mins up a river, 15mins if fast-flowing

Spring/autumn : cruise for 60mins at 3mph, 20mins up a river, 10mins if fast-flowing

Jan/Dec : stay moored up

 

 

 

Thats a good post. 

I have deleted some because I hate it when people quote big posts.

 

I suppose there will be new "made for electric" boats that will be only 15 inches deep and have really long swims etc, but the cruising time for an old working boat at 70 foot long at three foot deep will be dire.

The big issue that you point out is the rivers, even with a big battery bank and a charging point a full day on the Thames or Trent with a significant flow is going to need a lot of stored energy, and the consequences of running out of power could be a disaster.

 

A good electric car battery is 30kW-hour (and probably costs over £15,000) so for an 8 hour day on the river there will be 3.75kW available, that's just 5 horsepower.

 

Will people want to pay big money for a boat that can't do the Thames or the Ribble link and is a pig to handle because its too shallow? And how do you heat them in winter?

 

Maybe hydrogen is the only answer.

 

..............Dave

[nicknorman]

3 hours ago, peterboat said:

Its not a good option Nick, if one kilowatt of electricity moved a boat a mile it would take 4 kilowatts of electric to make the hydrogen to do the same, also you then have all the energy transporting the Hydrogen pumping it etc and the dangers of it. The science is now to move  hydrogen as ammonia as its safer, but this doesnt alter how energy inefficient it is especially the fuel cells, also factor in Hydrogen likes to crack metal and then leak! Its not for me but it will be good for real ships and HGV., The plan is instead of turning off wind turbines they will produce hydrogen with the electric instead of paying the companies to have turbines stood still, a win win

However you are not comparing like with like. Yes certainly there is significant inefficiency converting hydrogen to thrust, much more so than converting electricity to thrust. However there is also a lot of inefficiency in getting the electrical power to your boat, unless you are in a position to power it solely from solar which is not feasible for a narrowboat wanting to cruise for a day every day. Therefore there remains the problem of how to get the electricity to the boat and how it is generated. A huge amount of investment which consumes energy, just to install and maintain it. And of course there are transmission losses between power generation and end user. Yes we can have solar farms and windfarms but they don't work when its not sunny and not windy. If one is going to make hydrogen as you suggest, it will be much easier to tanker it to a boat than to install charging points all along the canal network.

 

Anyway, perhaps hydrogen is not the answer but I am thinking that energy stored in chemicals is much easier to distribute and store than electrical energy. It must be possible to synthesise some diesel equivalent from inert raw materials and electrical energy. It's just that no-one has bothered to do it yet.

[IanD]

25 minutes ago, dmr said:

 

Thats a good post. 

I have deleted some because I hate it when people quote big posts.

 

I suppose there will be new "made for electric" boats that will be only 15 inches deep and have really long swims etc, but the cruising time for an old working boat at 70 foot long at three foot deep will be dire.

The big issue that you point out is the rivers, even with a big battery bank and a charging point a full day on the Thames or Trent with a significant flow is going to need a lot of stored energy, and the consequences of running out of power could be a disaster.

 

A good electric car battery is 30kW-hour (and probably costs over £15,000) so for an 8 hour day on the river there will be 3.75kW available, that's just 5 horsepower.

 

Will people want to pay big money for a boat that can't do the Thames or the Ribble link and is a pig to handle because its too shallow? And how do you heat them in winter?

 

Maybe hydrogen is the only answer.

 

..............Dave

There's no way you can travel upstream on the Thames or Trent when flowing reasonably quickly for any length of time without a *far* bigger battery bank than anyone is currently installing in hybrids or electric boats, because going by the revs (about 2000) I found I needed on the Trent in August you need about 15kW/20bhp -- still nowhere near full throttle, but a lot for electric. A 48V 800Ah bank of traction cells (40kWh nominal) is down to under 600Ah (30kWh) when discharged at 0.4C, at 80% DOD that's 23kWh usable which will keep you going for an hour and a half.

12 minutes ago, nicknorman said:

However you are not comparing like with like. Yes certainly there is significant inefficiency converting hydrogen to thrust, much more so than converting electricity to thrust. However there is also a lot of inefficiency in getting the electrical power to your boat, unless you are in a position to power it solely from solar which is not feasible for a narrowboat wanting to cruise for a day every day. Therefore there remains the problem of how to get the electricity to the boat and how it is generated. A huge amount of investment which consumes energy, just to install and maintain it. And of course there are transmission losses between power generation and end user. Yes we can have solar farms and windfarms but they don't work when its not sunny and not windy. If one is going to make hydrogen as you suggest, it will be much easier to tanker it to a boat than to install charging points all along the canal network.

 

Anyway, perhaps hydrogen is not the answer but I am thinking that energy stored in chemicals is much easier to distribute and store than electrical energy. It must be possible to synthesise some diesel equivalent from inert raw materials and electrical energy. It's just that no-one has bothered to do it yet.

No, it's that none of them make sense from an energy efficiency point of view -- generating/storing/using hydrogen starting from fossil fuel is less efficient than burning it in a diesel engine (at least 2x worse than using batteries), and all the alternatives are even worse.

Edited October 13, 2020 by IanD

[peterboat]

4 minutes ago, IanD said:

There's no way you can travel upstream on the Thames or Trent when flowing reasonably quickly for any length of time without a *far* bigger battery bank than anyone is currently installing in hybrids or electric boats, because going by the revs (about 2000) I found I needed on the Trent in August you need about 15kW/20bhp -- still nowhere near full throttle, but a lot for electric. A 48V 800Ah bank of traction cells (40kWh nominal) is down to under 600Ah when discharged at 0.4C, at 80% DOD that's 23kWh usable which will keep you going for an hour and a half.

And yet dumb barges traveled up and down the Trent using mud weights no engine power at all, that is a fact. The answer is of course they were proper boaters that knew you dont fight the tide or current you let it do the work,

Also the 100 ton fully laden barges used to travel around with 20 hp listers again up and down the Trent how did they do that?

Edited October 13, 2020 by peterboat

[IanD]

Just now, peterboat said:

And yet dump barges traveled up and down the Trent using mud weights no engine power at all, that is a fact. The answer is of course they were proper boaters that knew you dont fight the tide or current you let it do the work

Thanks Peter, that's really helpful. Next time I'll ask the rain to unfall and the Trent to flow backwards, I'm sure that will do the job ?

[peterboat]

31 minutes ago, IanD said:

It doesn't matter what magic paint is used, all the numbers from various reputable sources (except Shine) and the experience of people on this forum say you need about 4bhp/3kW for a narrowboat cruising in a normal canal (not deep water) at normal speed (not rushing) -- estimates from Hybrid Marine, Victron prop calculator, engine efficiency curves from Integrel together with numbers reported by many people of 1.5l/hr typical diesel fuel consumption and their cruising revs given prop size and prop law all agree.

 

The only way to use less power than this is to slow down or cruise at 3mph on a deep canal/lake/river, which is why the Vicprop calculator predicts 4.2mph on 4bhp (standard hull resistance curves in deep water, you're not going to convince anybody that these are wrong). Past moored boats power is probably halved, and it's nil while waiting for a lock. If Shine have included plenty of these when working out total energy use for a day's leisurely travel, divided this by total hours, and then quoted *average* power in kW used over the day then their numbers make a bit more sense. But implying that you can "cruise along" while drawing 1-1.5kW is simply not credible unless you cruise more slowly than normal, they're definitely being "economical with the truth" to make their electric boat look better/more practical than it really is ?

 

If their numbers are right, why does it need a backup generator? Solar alone should generate plenty of power for cruising...

They have quoted their figures and given that I use 3 kw to do 3 mph yes deep water I can find them believable, I have pulled a narrowboat along with a rope and I am not 4 hp so how do I do that?

2 minutes ago, IanD said:

Thanks Peter, that's really helpful. Next time I'll ask the rain to unfall and the Trent to flow backwards, I'm sure that will do the job ?

It was the same for them they didnt try to fight the current or tide

[IanD]

36 minutes ago, peterboat said:

They have quoted their figures and given that I use 3 kw to do 3 mph yes deep water I can find them believable, I have pulled a narrowboat along with a rope and I am not 4 hp so how do I do that?

It was the same for them they didnt try to fight the current or tide

Your 3kW for 3mph in deep water with a wideboat agrees with 3kW for 3mph in a normal shallower canal with a narrowboat, the hull resistance will be similar. 1kW for cruising a narrowboat at normal speed is nonsense. I can pull a narrowboat too but at maybe 1 mph, which is what you'd expect given typical human power output of a few hundred watts. If there's no wind I can pull a loaded barge weighing hundreds of tons *very* slowly, that's the beauty of water transport but it doesn't disprove the numbers I've provided ?

 

How exactly do you suggest avoiding the current flowing down the Trent above the Soar junction (or down the Soar) after heavy rain, when the river currents are strong but not on red boards? The worst part was above the locks where there isn't any tide, the only solution I can see is not to travel until it's calmed down -- which is hardly an option with a boat that has to get back to the hire base.

 

Taking a relatively low-powered electric-only boat (without a *ginormous* battery bank) onto waters like these (or the Ribble Link, or various others) is simply risky, there's no way to fix this apart from not going there or being willing to wait days (or weeks...) for favourable conditions. Again that might be OK for you, but not for anybody who needs to get from A to B for whatever reason...

Edited October 13, 2020 by IanD

[Jen-in-Wellies]

The Thames used to have a tow path all the way along the navigable bits. Other rivers did too. It was how narrowboats got from London to Oxford. Reinstate that and remove anything that blocks the tow line, then you have a way to move an electric boat without flattening the batteries by a much more efficient towing tractor as a modern version of a horse on the path. On the Severn, a group of boats would be pulled by a tug. Have a tug for the river section with the ammonia power being proposed for coastal freight. Lots of ways of doing things, mostly worked out and regularly used a century, or two ago.

 

1 minute ago, peterboat said:

They have quoted their figures and given that I use 3 kw to do 3 mph yes deep water I can find them believable, I have pulled a narrowboat along with a rope and I am not 4 hp so how do I do that?

You put all your 250W or so in to moving the boat when bow hauling it from the bank side. With a propeller in water, a lot of the power is wasted thrashing the water around. It is why canals were built with tow paths for a horse (740 ish Watts max), rather than have the horse on the boat with a tread wheel to turn a paddle wheel, or prop.

Jen

[doratheexplorer]

2 hours ago, Jen-in-Wellies said:

So we are back to a proper electric charging post network for the system, or my idea of battery tow tractors on the tow path to get the propulsion power required down to less than 1hp (740W), which we know works as that is the power of one horse and could be charged from solar for normal narrowboat cruising in the summer without needing a charging post every day.

 

Jen

 

I remember this.  At first I thought it was a wind up.  The more I thought about it, the more I realised that you're a genius!  I was picturing big tractors.  What it would actually be is a compact, sit-on minature 'donkey' on wheels. Still needs something clever for singlehanders though, like some kind of steering AI for the boat.