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phasing out of fossil fuels - programme


magpie patrick

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2 hours ago, peterboat said:

 

 

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

And much kudos to you for doing a lot to advance the cause of electric boats ?

 

But you don't help your cause -- and probably actually hinder it -- by repeatedly over-stating some of the advantages and about how brilliant they are *for you*, living on a super-solar wideboat moored on a deep canal and not doing as much travelling as some people want to do. There are downsides to electric boats especially for people who don't share your lifestyle -- some of who are even "proper boaters" -- and it's important to recognise this, just like there are (huge) positive sides.

 

It also doesn't help when as someone who many view as experienced in this area you sometimes state "alternative facts" which don't agree with reality, like claiming that Finesse does 4mph on 1kW on a typical canal or that hydraulic gearboxes in a parallel hybrid absorb 25% of the power or that a 20hp electric motor is equivalent to a 43hp diesel or that all diesel boats are overpropped. I know you're (justifiably!) super-keen on electric boats, but all this over-egging the pudding on how fantastic they are and how rubbish diesels are just leads to flame wars with people like me, who hate people putting stuff out as the gospel truth which isn't supported by the facts.

 

So let's try and advance the cause of series hybrids (or electric boats) without doing this, because it's a worthwhile cause ?

Edited by IanD
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4 hours 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 that doesn't address my point. The working boat pairs of 80+ years ago didn't need that engine power. The large GU boats were designed to operate on the tidal Thames as well as the canals, and 18hp was sufficient then.

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1 hour ago, David Mack said:

But that doesn't address my point. The working boat pairs of 80+ years ago didn't need that engine power. The large GU boats were designed to operate on the tidal Thames as well as the canals, and 18hp was sufficient then.

But it does address your point, I specifically said "for extreme cases like the Ribble Link" --

 

 

"The advice from CRT is that if your boat can maintain 5knots (6mph) in deep still water you should be fine"

 

So let's see what speed Vicprop says a 70 ton pair will do in deep still water with an 18hp engine and a big slow prop -- the answer is 5mph. 6mph needs about 30hp (cube law).

 

Which suggests that the currents on the Thames -- or at least, when boatmen were willing to go out instead of stay moored up -- were weaker than on the Ribble Link, so funnily enough less power is needed. Which is also exactly what I said, if you don't need to be capable of doing this -- the hardest thing on the canals for an electric boat, because there's no avoiding the current by waiting -- you can reduce the motor power and battery/generator size.

 

For a "go-anywhere" electric/series hybrid narrowboat, a 15kW motor (with 30kWh battery and 7kW genny) looks like a good option, and one that is supported by several suppliers. If you're not so worried about "extreme boating" 10kW/20kWh/5kW should be fine, but may then lead to resale difficulties if 15kW becomes accepted as "the power to have" -- in the same way that a new 57' diesel boat is expected to have a 40hp-43hp diesel and 30hp is seen as underpowered, regardless of whether this is actually true it's what "the market" (i.e. boat buyers) think.

Edited by IanD
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20 hours ago, IanD said:

But it does address your point, I specifically said "for extreme cases like the Ribble Link" --

 

 

"The advice from CRT is that if your boat can maintain 5knots (6mph) in deep still water you should be fine"

 

So let's see what speed Vicprop says a 70 ton pair will do in deep still water with an 18hp engine and a big slow prop -- the answer is 5mph. 6mph needs about 30hp (cube law).

 

Which suggests that the currents on the Thames -- or at least, when boatmen were willing to go out instead of stay moored up -- were weaker than on the Ribble Link, so funnily enough less power is needed. Which is also exactly what I said, if you don't need to be capable of doing this -- the hardest thing on the canals for an electric boat, because there's no avoiding the current by waiting -- you can reduce the motor power and battery/generator size.

 

(snip)

 On the Thames, it is possible to avoid travelling against the tide: on the Ribble Link, you have to punch the tide in the early stages of the passage, either down the Douglas or down the Ribble, depending on your direction of travel. 

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I can't comment on everything that have been said since I launched the propeller debate but a couple of points do seem worth making.

 

1. We have 15 kW in a heavy (23 tonne) boat on a 2'6" draft. 2.25 kW gives us 3.3 mph in open water. Applying a cube law to this suggests 13.5 kW to reach 6 mph. I'm not sure exactly how much we do need, or what our revs are when we reach it, though we have certainly can. We haven't done the Ribble Link yet but, as I know several people with boats with similarly-powered DM2s who have done it without problem, I don't expect any other than running the batteries down quicker than usual. We certainly had no problems on the Irish rivers while we were out there.

 

2. One problem faced by diesels which I don't think has been raised is that much more torque is required to accelerate a propeller from rest to (typically) 400 rpm almost instantaneously when drive is engaged than to turn it subsequently. Older diesels had more torque because they developed their power at lower speeds. They also had heavier flywheels which also help to overcome the initial starting load. An electric motor, by contrast, starts its propeller progressively from rest so, while probably having more torque available, doesn't actually need as much.

 

Let me assure any doubters that 15 kW/20 hp is about right for an electric drive providing its propeller is large enough and slow enough.

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1 minute ago, Rishworth_Bridge said:

I can't comment on everything that have been said since I launched the propeller debate but a couple of points do seem worth making.

 

1. We have 15 kW in a heavy (23 tonne) boat on a 2'6" draft. 2.25 kW gives us 3.3 mph in open water. Applying a cube law to this suggests 13.5 kW to reach 6 mph. I'm not sure exactly how much we do need, or what our revs are when we reach it, though we have certainly can. We haven't done the Ribble Link yet but, as I know several people with boats with similarly-powered DM2s who have done it without problem, I don't expect any other than running the batteries down quicker than usual. We certainly had no problems on the Irish rivers while we were out there.

 

2. One problem faced by diesels which I don't think has been raised is that much more torque is required to accelerate a propeller from rest to (typically) 400 rpm almost instantaneously when drive is engaged than to turn it subsequently. Older diesels had more torque because they developed their power at lower speeds. They also had heavier flywheels which also help to overcome the initial starting load. An electric motor, by contrast, starts its propeller progressively from rest so, while probably having more torque available, doesn't actually need as much.

 

Let me assure any doubters that 15 kW/20 hp is about right for an electric drive providing its propeller is large enough and slow enough.

Glad you have made a reappearance its good to have another electric boater on here 

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13 minutes ago, Rishworth_Bridge said:

I can't comment on everything that have been said since I launched the propeller debate but a couple of points do seem worth making.

 

1. We have 15 kW in a heavy (23 tonne) boat on a 2'6" draft. 2.25 kW gives us 3.3 mph in open water. Applying a cube law to this suggests 13.5 kW to reach 6 mphI'm not sure exactly how much we do need, or what our revs are when we reach it, though we have certainly can. We haven't done the Ribble Link yet but, as I know several people with boats with similarly-powered DM2s who have done it without problem, I don't expect any other than running the batteries down quicker than usual. We certainly had no problems on the Irish rivers while we were out there.

 

2. One problem faced by diesels which I don't think has been raised is that much more torque is required to accelerate a propeller from rest to (typically) 400 rpm almost instantaneously when drive is engaged than to turn it subsequently. Older diesels had more torque because they developed their power at lower speeds. They also had heavier flywheels which also help to overcome the initial starting load. An electric motor, by contrast, starts its propeller progressively from rest so, while probably having more torque available, doesn't actually need as much.

 

Let me assure any doubters that 15 kW/20 hp is about right for an electric drive providing its propeller is large enough and slow enough.

err    ..........................   summat wrong somewhere.    I think you meant 135kW.

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It's the ratio of speeds that has to be cubed.

6/3.3 = 1.82 which, cubed, is 6.01.

Multiply that by the original 2.25 kW and you get 13.52 kW.

Given that, strictly speaking, the cubic relationship applies to spheres and not to long, thin objects like boats, I think that actually achieving 6 mph within 15 kW is close enough.

4 minutes ago, peterboat said:

My widebeam takes 3.3 kw to do 3 mph approx and 6 mph ish is 23kw its 12 foot wide with a wheelhouse and 33 tons ish 

The cube theory would suggest 24 so your 23 is pretty close.

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16 hours ago, Rishworth_Bridge said:

It's the ratio of speeds that has to be cubed.

6/3.3 = 1.82 which, cubed, is 6.01.

Multiply that by the original 2.25 kW and you get 13.52 kW.

Given that, strictly speaking, the cubic relationship applies to spheres and not to long, thin objects like boats, I think that actually achieving 6 mph within 15 kW is close enough.

The cube theory would suggest 24 so your 23 is pretty close.

Exactly I have a long swim boat made by a good shell builder and it's a direct drive system, with a high torque DC series electric motor, the propeller took some sorting but seems ok

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17 hours ago, Rishworth_Bridge said:

It's the ratio of speeds that has to be cubed.

6/3.3 = 1.82 which, cubed, is 6.01.

Multiply that by the original 2.25 kW and you get 13.52 kW.

 

I tried to tell them that but there's a load of arithmetically challenged folk on this thread. 

 

You just got the decimal point wrong.

Edited by Murflynn
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Firecrest's arrangement is somewhat unusual - in a number of ways. Firstly, it uses 2 x 10 kW motors on the same shaft. They, and their controllers, are from Piktronik in Slovenia. As far as I know, the motors are badged versions of those F-P used to sell before they switched to Bellmarine. Certainly Piktronik supplied controllers to F-P. Unusually, they have dual controllers and, as far as I know, this setup hasn't worked very well, failing to get anywhere near their theoretical 1,200 rpm maximum. Fortunately, what they will do is plenty as 20 kW is much more than is needed. Firecrest also has a 4-bladed propeller as it doesn't have enough draft to take a 3-bladed one as large as ours.

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10 minutes ago, Rishworth_Bridge said:

Firecrest's arrangement is somewhat unusual - in a number of ways. Firstly, it uses 2 x 10 kW motors on the same shaft. They, and their controllers, are from Piktronik in Slovenia. As far as I know, the motors are badged versions of those F-P used to sell before they switched to Bellmarine. Certainly Piktronik supplied controllers to F-P. Unusually, they have dual controllers and, as far as I know, this setup hasn't worked very well, failing to get anywhere near their theoretical 1,200 rpm maximum. Fortunately, what they will do is plenty as 20 kW is much more than is needed. Firecrest also has a 4-bladed propeller as it doesn't have enough draft to take a 3-bladed one as large as ours.

That explains its high power usage in comparison to yours and mine. Finness are seeing figures similar to yours and I am not surprised that I am using 3.3kw at 3mph

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34 minutes ago, peterboat said:

That explains its high power usage in comparison to yours and mine. Finness are seeing figures similar to yours and I am not surprised that I am using 3.3kw at 3mph

Peter, you're yet again arguing that because your boat in deep water uses a given power to do 3mph, a narrowboat needs less. Which it would, if it was on your nice deep canal. Unfortunately most boats aren't.

 

All the things about motors and 4-bladed props or big props vs. small ones are red herrings, these make small differences. What makes the biggest difference by far is speed (power is speed cubed) and shallow/narrow canals vs. deep water -- if these slow the boat down by only 20% at a given power level (which seems reasonable from experience) then you need 2x the power to get back up to the same speed. This is why you keep coming up with low power estimates and I keep coming up with higher ones.

 

Rishworth_Bridge's figure is 2.25kW to do 3.3mph in open water. Take 20% off speed for a "normal" canal and you get 2.7mph. To get back up to 3mph needs exactly 3kW...

 

Or if you turn this round and ask what power *at the prop* a normal diesel boat cruises at on a typical canal, the answer comes out close to 3kW/4bhp, which is 1.5l/hr fuel consumption.

 

When I take your numbers or Rishworth_Bridge's or Firecrest's or real numbers from Finesse (who I'm talking to right now, thank you for the recommendation) and adjust them for speed/boat size/water depth, they all end up agreeing with mine and the diesel's, 3kW for 3mph cruising on a normal canal.

 

So I honestly don't see what your argument is ?

Edited by IanD
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35 minutes ago, IanD said:

Peter, you're yet again arguing that because your boat in deep water uses a given power to do 3mph, a narrowboat needs less. Which it would, if it was on your nice deep canal. Unfortunately most boats aren't.

 

All the things about motors and 4-bladed props or big props vs. small ones are red herrings, these make small differences. What makes the biggest difference by far is speed (power is speed cubed) and shallow/narrow canals vs. deep water -- if these slow the boat down by only 20% at a given power level (which seems reasonable from experience) then you need 2x the power to get back up to the same speed. This is why you keep coming up with low power estimates and I keep coming up with higher ones.

 

Rishworth_Bridge's figure is 2.25kW to do 3.3mph in open water. Take 20% off speed for a "normal" canal and you get 2.7mph. To get back up to 3mph needs exactly 3kW...

 

Or if you turn this round and ask what power *at the prop* a normal diesel boat cruises at on a typical canal, the answer comes out close to 3kW/4bhp, which is 1.5l/hr fuel consumption.

 

When I take your numbers or Rishworth_Bridge's or Firecrest's or real numbers from Finesse (who I'm talking to right now, thank you for the recommendation) and adjust them for speed/boat size/water depth, they all end up agreeing with mine and the diesel's, 3kW for 3mph cruising on a normal canal.

 

So I honestly don't see what your argument is ?

You can't run two motors together on different controllers Ian I know this because of James experience, it ran very badly and used lots of power.

Riccy is a  nice guy and should have what you want. 

Boat wise James has a stunning narrowboat that he has built, it has a gardner in it, he used to build boats for a living his would be one to buy, rip the gardner out and put a electric motor in it job done The detail work on it is out of this world, its really riveted together! Not Hudson's imitation ones. It's on the Thames at Richmond so your neck of the world 

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There is a lot of truth in what 1268 says about channel dimensions, which is why I tend to stick to open water figures which are consistent. When cruising we tend to stick to 2.25 kW and accept whatever speed we get. In a broad canal in reasonable condition (eg the Paddington Branch) it gives us just about 3 mph. Narrow canals are very variable but putting 2.3 mph into CanalPlan usually gives reasonably accurate times. That might suggest that we travel a lot slower than other boats but we rarely (maybe a couple of times a week) get caught and passed by another boat so any difference can't be that great, meaning that other boats are being similarly slowed. If we were on a 24" draft (the shallowest which would take our prop) rather than 30" we would travel faster, though the maths is far more complex than the simple cube law and way beyond me. One thing that the diesel advocates might like to consider, however, is fuel consumption. I can't be absolutely precise about our cruising fuel usage because it is difficult to separate out from the total but my best estimate is that it is 0.5-0.6 litres/hour. A modern diesel would probably use something like 1.5 litres while an older one like a Russell-Newbury DM2, or even a Lister SR3, would be around 1 litre.

 

Changing topic, if we hadn't gone electric I would have been looking for a Gardner. They're gorgeous.

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