Jump to content

phasing out of fossil fuels - programme


magpie patrick

Featured Posts

31 minutes ago, ditchcrawler said:

As I have often said, I wonder how many of these boats with the higher Hp engines actually get those Hp out of the propellers

As I have been saying a lot are over propped and can't get anywhere near the headline figure.

My widebeam has 23kw or did before I upped the voltage so it could be more and its been sufficient for canals and rivers around me

Link to comment
Share on other sites

16 minutes ago, jetzi said:

Could anyone explain in a nutshell what the problem is with getting power to the propellers?

 

Are people putting too-large motors with too-small props?

Large engines with props that are to large, which means that the engine doesn't get into its maximum power band. Over proping is common as itt reduces fuel consumption and makes for quiet cruising.  Remember most canal boats stay on canals so never a problem. Electric motors like mine create maximum torque all the way from zero to maximum rpm, so very flat torque line in acceleration. Diesels don't do that 

Edited by peterboat
Link to comment
Share on other sites

3 minutes ago, peterboat said:

Large engines with props that are to large, which means that the engine doesn't get into its maximum power band. Over proping is common as itt reduces fuel consumption and makes for quiet cruising.  Remember most canal boats stay on canals so never a problem 

And some are the other way and will hit max revs as fast as you can push the lever forward without a great load on the engine

Link to comment
Share on other sites

1 minute ago, ditchcrawler said:

And some are the other way and will hit max revs as fast as you can push the lever forward without a great load on the engine

True my first boat was an ex hire boat and under propped which I sorted, my next 2 boats were way over propped 

Link to comment
Share on other sites

12 minutes ago, peterboat said:

True my first boat was an ex hire boat and under propped which I sorted, my next 2 boats were way over propped 

I think the old Canal Time were a good example of it, engine reving like billyo and going nowhere fast

  • Greenie 1
Link to comment
Share on other sites

39 minutes ago, ditchcrawler said:

I think the old Canal Time were a good example of it, engine reving like billyo and going nowhere fast

I think a lot of hire boats are/were the same,  bigger profits on diesel on return plus less likely to be speeding?

Link to comment
Share on other sites

1 hour ago, jetzi said:

Could anyone explain in a nutshell what the problem is with getting power to the propellers?

 

Are people putting too-large motors with too-small props?

It's a balance between blade area (BAR) & pitch, BAR transmits power, pitch defines its gearing, too coarse a pitch and boat will accelerate too quickly when first engaged, so BAR then has to be smaller to attain very near max engine speed. Correct pitch is then followed by correct BAR to absorb max power, best if it can be achieved with standard 55% BAR (larger dia props turn slower to minimise cavitation) if a larger diameter won't fit then a bigger than 55% will be needed to give a wider blade in a smaller dia, or go for 4 blades (not always ideal)

Over propping does give lower cruising revs but engine is overloaded at higher revs and will overfuel with black smoke. 

It's affected by other things but those are the basics as related to me by Crowther Props, sadly no longer operating. 

 

Tin hat on

4 minutes ago, peterboat said:

I think a lot of hire boats are/were the same,  bigger profits on diesel on return plus less likely to be speeding?

Better for engine life to be lightly loaded than overloaded. 

Edited by nb Innisfree
  • Greenie 1
Link to comment
Share on other sites

8 minutes ago, peterboat said:

I think a lot of hire boats are/were the same,  bigger profits on diesel on return plus less likely to be speeding?

My ex-hire boat had a 3:1 gearbox so the hirers 'going by the noise' (revs) thought they were going fast.

 

 

  • Greenie 1
Link to comment
Share on other sites

8 hours ago, nb Innisfree said:

It's a balance between blade area (BAR) & pitch, BAR transmits power, pitch defines its gearing, too coarse a pitch and boat will accelerate too quickly when first engaged, so BAR then has to be smaller to attain very near max engine speed. Correct pitch is then followed by correct BAR to absorb max power, best if it can be achieved with standard 55% BAR (larger dia props turn slower to minimise cavitation) if a larger diameter won't fit then a bigger than 55% will be needed to give a wider blade in a smaller dia, or go for 4 blades (not always ideal)

Over propping does give lower cruising revs but engine is overloaded at higher revs and will overfuel with black smoke. 

It's affected by other things but those are the basics as related to me by Crowther Props, sadly no longer operating. 

 

Tin hat on

Better for engine life to be lightly loaded than overloaded. 

Diesel engines are better worked than not

Link to comment
Share on other sites

7 hours ago, David Mack said:

All the above may well be true for a typical diesel powered narrow boat. But why does an electric one need need a 20kW peak power motor?

The same reason diesel boats have big engines even if they typically run about 3kW/4bhp at the prop -- you need far more than this on rivers, see the Ribble Link thread, and also to stop quickly in an emergency. At least 15kW/20bhp is a good figure, more than that (e.g. 25kW) would give capabilities similar to modern diesels (for the rare cases when full power is needed) but then battery capacity becomes a problem...

10 hours ago, peterboat said:

As I have been saying a lot are over propped and can't get anywhere near the headline figure.

My widebeam has 23kw or did before I upped the voltage so it could be more and its been sufficient for canals and rivers around me

And as other people have been saying, a lot are correctly proper or underpropped. Your experiences are not everybody's...

Edited by IanD
Link to comment
Share on other sites

19 hours ago, Dr Bob said:

Bit in red......No it isnt!

There is a big flaw in your argument. Is it better to eat all the green stuff or burn it in ICE's? You say it is no different. Unfortunately it is.

If you sequester say 100Kgs of CO2 out of the atmosphere to make some algae, then make biofuel out of it and burn it, then you put 100Kgs of CO2 back in the atmosphere, +/- any extras such as power etc.

If you sequester 100Kg of CO2 out of the atmosphere to make some algae and turn that to food for humans to eat, then only part of the carbon goes back to CO2. When you eat, part of the carbon you put in you gut goes into the blood stream and  helps the body function and a large part of that is burnt and exhaled as CO2. The other part of what you eat though is not taken in by the body and is excreted in the form of poo and wee. These streams contain carbon. How much? Dunno? 50% of what you eat maybe? Of the carbon you eat ending up in sewarage, a part of that will not end up as CO2. In aerobic composting, only 2/3rd of carbon ends up in CO2 and in anerobic it is less - so say 1/2. Therefore quite a bit of the CO2 sequestered from the atmosphere ends up as solids on the surface of the planet. It doesnt all end up back as CO2. Where do you think all the oil and gas we drill for come from? Its from green stuff that decays but doesnt all go back to CO2.

Therefore by growing plants for us to eat, thereby taking CO2 out of the atmosphere, if we eat it and compost our waste, then we have sequestered significant CO2 from the atmosphere. If however we just grow to burn in an ICE, then we just return 100% of the CO2 back to the atmosphere. It is actually worse than that as the growing of the algae takes energy which is then a net negative on the ICE burning case whereas on the eating case, we get energy back in the composting stage as a result of the CO2 formed (it is an exothermic reaction).

Your assertion that it is a closed cycle and carbon neutral is not quite right. Burning hydrocarbon fuels is bad for the environment. The more green stuff we grow is better for the environment. So lets not burn it and get our energy from other sources.

so if we eat all the green stuff on the planet and do not replace it the problem is solved. 

break the cycle.

all higher animals will die off including ourselves, plants will evolve again and the planet will thrive again.

  • Greenie 1
Link to comment
Share on other sites

32 minutes ago, Murflynn said:

so if we eat all the green stuff on the planet and do not replace it the problem is solved. 

break the cycle.

all higher animals will die off including ourselves, plants will evolve again and the planet will thrive again.

Fazackerly.

Link to comment
Share on other sites

1 hour ago, IanD said:

The same reason diesel boats have big engines even if they typically run about 3kW/4bhp at the prop -- you need far more than this on rivers, see the Ribble Link thread, and also to stop quickly in an emergency. At least 15kW/20bhp is a good figure, more than that (e.g. 25kW) would give capabilities similar to modern diesels (for the rare cases when full power is needed) but then battery capacity becomes a problem...

And as other people have been saying, a lot are correctly proper or underpropped. Your experiences are not everybody's...

No they haven't Ian as very few are posting its fairly neutral, plus a lot don't know 

 

31 minutes ago, nb Innisfree said:

Yes but not overloaded

But it happens because people want quiet economic cruising and never go near a tidal river, they are scared of the dragons that live below?

Link to comment
Share on other sites

11 minutes ago, nb Innisfree said:

That's the beauty of electric drive, max torque & silence from zero revs so just choose your speed, add a speaker to give a comforting old world steady thump if you want. 

Very true but i prefer the silence, as an aside I am looking at an I3 rex with luck

Edited by peterboat
Link to comment
Share on other sites

10 hours ago, David Mack said:

All the above may well be true for a typical diesel powered narrow boat. But why does an electric one need need a 20kW peak power motor?

 

34 minutes ago, nb Innisfree said:

That's the beauty of electric drive, max torque & silence from zero revs so just choose your speed,

 

Roughly speaking, wouldn't an electric drive only use as much power as you give it - better to have and not need than need and not have? I guess it's about the most efficient running speed.

So, isn't the ideal a motor/prop combination that runs most efficiently to propel your boat at 3-4mph in still water, but is capable of double (or triple) that power if you get into trouble on a river?

Link to comment
Share on other sites

14 hours ago, David Mack said:

 

And yet a working narrow boat pair had a diesel engine of 18 hp capable of propelling two boats, each over 20m long, and with a combined weight of 60-70 tons.

Surely if electric power needs to be used economically to make best use of limited energy storage, then we shouldn't need to specify almost twice the engine power to move a fraction of the load that we could do 80+ years ago!

This is the big question that we keep coming back to -- how much power is *really* needed?

 

It's clear that under almost all conditions narrowboats need far lower power then diesels fitted today could provide -- the steamer (Keith Jones's "Firefly") that we hired back in the 80s had at most 3hp and that got us from Foxton to Windmill End and back just fine, if a teeny bit more slowly than a diesel especially on narrow/shallow canals. But if you wanted to stop in a hurry it was absolutely hopeless, and I wouldn't have dreamed of taking it out onto any river. The loads being moved commercially also often travelled more slowly than many (most?) modern boats, as films show, and would often be run much closer to full throttle than boats today. 18hp flat out for 70 tons would move about as fast as 3kW/4hp would move a 15 ton boat today, which is normal cruising power.

 

The diesels fitted to narrowboats today follow the same power/foot rules as the ones Waterworld quote, which I guess are intended for boats that go out on rivers -- but even then maximum power is rarely needed, the Ribble link seems to be one of the few cases where engines are really pushed. Builders tend to fit the engine sizes recommended by the engine suppliers, possibly to avoid any risk of being accused of supplying an underpowered boat if anything ever goes wrong on a river. People who buy boats then expect the power of the engine to be what's normally fitted, for the same reason. And there's no big problem with (for example) installing a 43hp diesel instead of a 30hp one, so that's what happens, everybody is happy.

 

There's little doubt that if you want an electric motor to provide the same power at the prop as today's diesels it would need to be somewhere around 25kW for a typical 57' boat with a 43hp diesel, but this needs motor/controller/batteries which are bigger and more expensive than normally fitted today -- and apart from this, this much power isn't needed except in very rare circumstances, and maybe not even then going by the comments on the Ribble Link thread, it looks like 15kW/20hp is enough even here. This also makes the electrics much easier.

 

So I agree that with electric/series hybrid boats we don't need the same maximum (usable at the prop) power as modern diesels, especially given battery capacity issues -- and there's absolutely no point having more power if the batteries run out halfway along the Ribble link. A 15kW motor with 30kWh batteries and a 7kW generator will deal with anything that is ever going to be thrown at a narrowboat today -- yes it's less power than the modern diesels typically fitted, but it doesn't need to be this powerful, they are really overkill for this use.

 

If you're confident that the boat you're building will never be put under such stress (e.g. Ribble Link, Trent after rain) then of course you can install lower-power everything and save money. But if this then falls below the "expected norm" (e.g. 15kW) of electric boats, then -- just like a small diesel today -- it might make the boat difficult to sell on later.

  • Greenie 1
Link to comment
Share on other sites

32 minutes ago, jetzi said:

 

 

Roughly speaking, wouldn't an electric drive only use as much power as you give it - better to have and not need than need and not have? I guess it's about the most efficient running speed.

So, isn't the ideal a motor/prop combination that runs most efficiently to propel your boat at 3-4mph in still water, but is capable of double (or triple) that power if you get into trouble on a river?

Yes, except that the maximum power needed is way more than 2x or 3x, because it goes up with the cube of speed. If it takes 3kW/4hp (or whatever number you pick) for your 3.5mph in still water, maintaining the same speed against a 3 knot current (or doubling the speed) needs 8x the power.

  • Greenie 1
Link to comment
Share on other sites

1 hour ago, peterboat said:

No they haven't Ian as very few are posting its fairly neutral, plus a lot don't know 

 

But it happens because people want quiet economic cruising and never go near a tidal river, they are scared of the dragons that live below?

You always think your experiences and knowledge are more valuable then everyone else's don't you?

 

Read back through the thread, and if you want go and dig out all the other comments here (and elsewhere -- this isn't the only forum about boats, or even narrowboats) about boats being underpropped and overpropped.

 

What you'll find is that complaints about both under and over propping are common, as are "but my boat's correctly propped" replies.

 

So different people have different experiences but all three cases happen, which is exactly what I said ?

Link to comment
Share on other sites

2 hours ago, peterboat said:

But it happens because people want quiet economic cruising and never go near a tidal river, they are scared of the dragons that live below?

In some places, going by reported actual cruising patterns, a lot of boats need hardly any power at all as they rarely move much further than the other side of the marina and back (and in some cases they even delegate the annual fuel top-up - a couple of litres - to 'the staff').

 

If a designer sized a boat/engine on the basis of averages I suspect the result would generally be very unsatisfactory. As with almost any design task, the start point must always be a statement of intended usage/expected outputs or whatever. Unless you start from that you will inevitably end up with an unsatisfactory design, except by pure chance, or by doing what everyone else does. This is all the more important when an average disguises a very segmented market in which very few people match the average.

 

Incidentally, our first boat that we bought was a tiny 20ft ex early BW hire boat that had an aging 5hp Johnson outboard. Because it drew very little and had a good cruiser like hull shape, and going by the times recorded in our old logs, we made better speed than most boats today. We even made the passage down the Trent to Keadby and from Worcester to Tewkesbury on the Severn without in any case feeling that we had insufficient power. On the other hand, there were plenty of other characteristics that look horrifying in today's safety culture!!! (The Ribble Link was not even an idea back then - 1960's. OK, so perhaps the idea dated back 200 years but that was not quite the same)

 

The one - and about the only one - reliable conclusion from this lengthy debate that I can find is just that: whether or not you adopt and individual design depends on your intentions and that it is no use advocating one design over another by telling the other user that they have the wrong intentions!

Link to comment
Share on other sites

38 minutes ago, IanD said:

This is the big question that we keep coming back to -- how much power is *really* needed?

 

It's clear that under almost all conditions narrowboats need far lower power then diesels fitted today could provide -- the steamer (Keith Jones's "Firefly") that we hired back in the 80s had at most 3hp and that got us from Foxton to Windmill End and back just fine, if a teeny bit more slowly than a diesel especially on narrow/shallow canals. But if you wanted to stop in a hurry it was absolutely hopeless, and I wouldn't have dreamed of taking it out onto any river. The loads being moved commercially also often travelled more slowly than many (most?) modern boats, as films show, and would often be run much closer to full throttle than boats today. 18hp flat out for 70 tons would move about as fast as 3kW/4hp would move a 15 ton boat today, which is normal cruising power.

 

The diesels fitted to narrowboats today follow the same power/foot rules as the ones Waterworld quote, which I guess are intended for boats that go out on rivers -- but even then maximum power is rarely needed, the Ribble link seems to be one of the few cases where engines are really pushed. Builders tend to fit the engine sizes recommended by the engine suppliers, possibly to avoid any risk of being accused of supplying an underpowered boat if anything ever goes wrong on a river. People who buy boats then expect the power of the engine to be what's normally fitted, for the same reason. And there's no big problem with (for example) installing a 43hp diesel instead of a 30hp one, so that's what happens, everybody is happy.

 

There's little doubt that if you want an electric motor to provide the same power at the prop as today's diesels it would need to be somewhere around 25kW for a typical 57' boat with a 43hp diesel, but this needs motor/controller/batteries which are bigger and more expensive than normally fitted today -- and apart from this, this much power isn't needed except in very rare circumstances, and maybe not even then going by the comments on the Ribble Link thread, it looks like 15kW/20hp is enough even here. This also makes the electrics much easier.

 

So I agree that with electric/series hybrid boats we don't need the same maximum (usable at the prop) power as modern diesels, especially given battery capacity issues -- and there's absolutely no point having more power if the batteries run out halfway along the Ribble link. A 15kW motor with 30kWh batteries and a 7kW generator will deal with anything that is ever going to be thrown at a narrowboat today -- yes it's less power than the modern diesels typically fitted, but it doesn't need to be this powerful, they are really overkill for this use.

 

If you're confident that the boat you're building will never be put under such stress (e.g. Ribble Link, Trent after rain) then of course you can install lower-power everything and save money. But if this then falls below the "expected norm" (e.g. 15kW) of electric boats, then -- just like a small diesel today -- it might make the boat difficult to sell on later.

 

25 minutes ago, IanD said:

You always think your experiences and knowledge are more valuable then everyone else's don't you?

 

Read back through the thread, and if you want go and dig out all the other comments here (and elsewhere -- this isn't the only forum about boats, or even narrowboats) about boats being underpropped and overpropped.

 

What you'll find is that complaints about both under and over propping are common, as are "but my boat's correctly propped" replies.

 

So different people have different experiences but all three cases happen, which is exactly what I said ?

 

6 minutes ago, Mike Todd said:

In some places, going by reported actual cruising patterns, a lot of boats need hardly any power at all as they rarely move much further than the other side of the marina and back (and in some cases they even delegate the annual fuel top-up - a couple of litres - to 'the staff').

 

If a designer sized a boat/engine on the basis of averages I suspect the result would generally be very unsatisfactory. As with almost any design task, the start point must always be a statement of intended usage/expected outputs or whatever. Unless you start from that you will inevitably end up with an unsatisfactory design, except by pure chance, or by doing what everyone else does. This is all the more important when an average disguises a very segmented market in which very few people match the average.

 

Incidentally, our first boat that we bought was a tiny 20ft ex early BW hire boat that had an aging 5hp Johnson outboard. Because it drew very little and had a good cruiser like hull shape, and going by the times recorded in our old logs, we made better speed than most boats today. We even made the passage down the Trent to Keadby and from Worcester to Tewkesbury on the Severn without in any case feeling that we had insufficient power. On the other hand, there were plenty of other characteristics that look horrifying in today's safety culture!!! (The Ribble Link was not even an idea back then - 1960's. OK, so perhaps the idea dated back 200 years but that was not quite the same)

 

The one - and about the only one - reliable conclusion from this lengthy debate that I can find is just that: whether or not you adopt and individual design depends on your intentions and that it is no use advocating one design over another by telling the other user that they have the wrong intentions!

So i own and have built two electric boats, I am helping somebody build a third, have two other friends with electric boats and Riccy from Finesse is a friend of mine and they specialize electric boats. I am not a guru or anything else but I know they work, I know their limitations and I am happy to accept criticism from others that have done the same, the only person that had an electric boat posted on here briefly and then clearly decided it wasnt worth the effort when he was told his boat wouldnt work. I am going to do the same and let others that have more experience do their stuff

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.