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Electric?


andy4502

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3 minutes ago, ditchcrawler said:

Surly until there are lots of electric  the charging point wont appear, just like cars with hybrid systems which will soon be replaced by all electric with more charging points popping up each month. 

I think the real idea is we charge at home, they are putting in lamp post chargers and ones that pop up out of the ground so we are moving forward gently. I look at Norway where the majority of cars sold now are electric so we will be a few years behind them

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3 minutes ago, peterboat said:

I think the real idea is we charge at home, they are putting in lamp post chargers and ones that pop up out of the ground so we are moving forward gently. I look at Norway where the majority of cars sold now are electric so we will be a few years behind them

We are going to need a lot of lamposts. ??????

 

 

201743_175610.jpg

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3 minutes ago, The Happy Nomad said:

Lol.

 

I guess you are not a regular user of public transport.??

There is less than no chance of enough pubic transport to get millions to work that use cars today.

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28 minutes ago, peterboat said:

I used to be the tram operates very near to my boat, pointless getting a car out most times especially when you factor in beer

Yeah all these densely populated areas have trams.........

Edited by The Happy Nomad
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Just now, peterboat said:

nope just telling you how it is

Theres no public transport whatsoever for hundreds of thousands maybe millions of people in rural areas as it is. Who is going to finance endless lectric buses to all these places where people drive to work from?

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Just now, The Happy Nomad said:

Yeah all these densely populated have trams.........

Precisely and when the ones in Nottingham were built taking years whilst i was there it still remains impossible to get to work on them unless walking miles to the tram route and not enough evening and non during the night. Nearest stop 2 miles from where we moored at one end and further at the other.

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4 minutes ago, mrsmelly said:

There is less than no chance of enough pubic transport to get millions to work that use cars today.

My daughter once had a job in a town around five miles away.

 

It took three buses and an hour and a half to do those five miles. Often one wouldnt turn up meaning she was often very late for work.

 

It spurred her on to pass her test and get a car.

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5 minutes ago, The Happy Nomad said:

My daughter once had a job in a town around five miles away.

 

It took three buses and an hour and a half to do those five miles. Often one wouldnt turn up meaning she was often very late for work.

 

It spurred her on to pass her test and get a car.

I moor in wealthy oxfordshire only 3 miles out of Banbury and there are NO buses pass the gate. Nearest is a mile walk in the rain up  a fast road with no footpath. Bro in law lives in Lincolnshire and no buses for several miles but lots of people to drive to work. It aint gonna happen for a long time yet.

Edited by mrsmelly
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57 minutes ago, IanD said:

No, no, and a thousand times no...

 

Let's say you have a given force in the rope pulling the boat, the tractor is moving at 1mph and the current at 3mph. The engine power needed by the tractor is force*1mph (because power=force*speed), in whatever units you want to work, because the tractor is pushing against the grounds and it's moving over it at 1mph. The engine power needed by the propeller is force*4mph, because the propeller is pushing against the water and it's moving past it at 4mph and the force needed to pull the boat is the same. So the boat engine needs 4x the power of the tractor engine.

 

I don't see how much more clearly can I explain this, it's basic definitions of force and work and power.

Close but not quite there

 

The load the tractor pulls is increased by the speed of water past the boat, but the speed the tractor has to travel at does not - in your example the tractor still only has to do 1mph, whereas the propeller has to do 4mph, 

 

On the Danube at Iron Gates they used locomotives on the bank to pull boats up the rapids for this reason, the current ran faster than any vessel could reasonably be expected to go. In the end they did the sensible thing and built locks...

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

What I was actually saying, if you read carefully, is that nothing is free - whatever energy source you use you will be consuming something irreplaceable in the universe. More specifically I was commenting that the construction of batteries and solar panels use materials which are fast becoming scarce. (they never were all that plentiful in some cases). 

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6 minutes ago, magpie patrick said:

Close but not quite there

 

The load the tractor pulls is increased by the speed of water past the boat, but the speed the tractor has to travel at does not - in your example the tractor still only has to do 1mph, whereas the propeller has to do 4mph, 

 

On the Danube at Iron Gates they used locomotives on the bank to pull boats up the rapids for this reason, the current ran faster than any vessel could reasonably be expected to go. In the end they did the sensible thing and built locks...

The force is the same in both cases, it's what it takes to pull the boat through the water at 4mph (which is why I deliberately didn't put a number in, because it's higher than the force to pull it at 3mph).

 

The speed/power difference is exactly what you said, 4x higher power (ignoring propeller losses) for the propeller compared to the tractor.

 

Maybe you can see how to explain this to dmr, I keep trying but failing? ?

43 minutes ago, dmr said:

OK this is maybe my last go because its time for an early evening beer.

 

Lets imagine the boat getting towed by a little helicopter flying just above the water, the only things that matter are speed and force. The force is the tension in the tow rope (and this depends on water speed). The speed that goes into "power = force times speed" must be speed over the land because the helicopter has no knowledge that it is flying over moving water????

We need Nick Norman now, this is his neck of the woods?

 

There are of course many second order effects relating to prop behavior at different water flow rates (slip)

 

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

See my reply to Magpie Patrick.

Edited by IanD
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1 minute ago, Mike Todd said:

What I was actually saying, if you read carefully, is that nothing is free - whatever energy source you use you will be consuming something irreplaceable in the universe. More specifically I was commenting that the construction of batteries and solar panels use materials which are fast becoming scarce. (they never were all that plentiful in some cases). 

Fortunately scientists are changing things solar panels for one I was surprised to find, batteries wise same again what we have I doubt will be what we have in a few years time, what is for certain is oil is on the way out

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47 minutes ago, dmr said:

OK this is maybe my last go because its time for an early evening beer.

 

Lets imagine the boat getting towed by a little helicopter flying just above the water, the only things that matter are speed and force. The force is the tension in the tow rope (and this depends on water speed). The speed that goes into "power = force times speed" must be speed over the land because the helicopter has no knowledge that it is flying over moving water????

We need Nick Norman now, this is his neck of the woods?

 

There are of course many second order effects relating to prop behavior at different water flow rates (slip)

 

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

I have to agree with Ian on this one - sorry! The force required to push the boat is the same regardless of whether the force is applied by the prop or by the tractor, but due to the current the speed at which the force is applied is much higher for the prop than for the tractor, hence the tractor requires much less power than the prop, even disregarding the relative efficiencies.

 

Using the helicopter analogy, a helicopter requires a LOT more power to hover out of ground effect, than it does in forward flight at modest speed. Bear in mind that aircraft including helicopters remain aloft by pushing (accelerating) air down. So in the hover, the helicopter is pushing down on air that has already been pushed down - ie it is in a column of already descending air. Whereas the helicopter in forward flight is constantly encountering new air that is not already moving downwards fast, it therefore requires a lot less power to accelerate the air downwards to generate the lift.

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2 hours ago, Jen-in-Wellies said:

 

 

Or stick the handbrake on.In which case, you are limited by the weight and tyre friction of the tow vehicle to avoid being dragged in to the water. Splash!

that would happen even if you were trying to drive.  if the load on the towrope is sufficient you will still go splash, but with your wheels spinning impotently.

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50 minutes ago, Alan de Enfield said:

 

Just think of all the happy dogs (and the potential for electrocution of said dogs)

 

Have you ever seen a Dog cocking its leg against an electric fence ?

I tried this once when I was about 7 years old. We had a an electric fence around the gardens on our estate partly to keep the geese from wandering off. 

 

Pissing on an electric fence is not a very good thing to do. 

 

The odd thing is I did it again just to see if it had the same effect. Yes it did. It's a sort of "jolt" thing. 

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15 minutes ago, magnetman said:

I tried this once when I was about 7 years old. We had a an electric fence around the gardens on our estate partly to keep the geese from wandering off. 

 

Pissing on an electric fence is not a very good thing to do. 

 

The odd thing is I did it again just to see if it had the same effect. Yes it did. It's a sort of "jolt" thing. 

The definition of insanity is doing the same thing a number of times and expecting a different result.

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