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Post by Deleted on Jun 17, 2021 14:52:30 GMT
How much thrust power does a 57ft narrowboat need, on average?
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Post by JohnV on Jun 17, 2021 15:02:54 GMT
dunno but twin Rolls Royce Spey Turbofans worked for Thrust landspeed
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Post by Deleted on Jun 17, 2021 15:05:45 GMT
dunno but twin Rolls Royce Spey Turbofans worked for Thrust landspeed Don't think the fishermen will approve..
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Post by JohnV on Jun 17, 2021 15:53:12 GMT
Actually Dave, I don't think there is such a thing as a correct answer.
majority of "average narrowboats" have the hydrodynamic efficiency of a house brick.
Some do have a decent hull shape but they are the minority, most can still be made to achieve canal speeds of 3 to 4 mph with very small power ........ but stopping them is a very different matter.
You will probably get as many different answers as there are people who answer.
In my opinion, generally narrowboats are over engined for what is actually needed but then the requirements for "comfortable" boating are not just limited to what will actually "do the job".
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Post by Deleted on Jun 17, 2021 15:54:06 GMT
It's a good question.
250 lbs thrust should do it but take it easy and make sure everyone is aware of your priority of passage.
I'd love to see all canal boats converted to low power electric drive and everyone just glides about.
You'd have to learn to steer properly and regain old skills.
Once upon a time it was full of horse drawn boats which could not stop quickly. Must have been a lovely thing to watch.
Very graceful.
Probably loads of swearing too.
Drive pods mounted in rudder is the way to go I think.
Vectored thrust and you get to keep your diesel engine undisturbed.
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Post by Deleted on Jun 17, 2021 16:04:12 GMT
An example is the Aquamot 4.3kw pod motor which is 4.3kw (I used my slide rule for that) and rated at 197lbs thrust.
Obviously the propeller will make all the difference for a heavy boat but I reckon it is not beyond the wit of man to develop a slow turning sensored brushless motor in a pod with a two blade propeller which will line up with the rudder when not in use.
That way you could use the diesel for the main work and switch across to electric as and when.
I reckon done right a lot of the diesel engines would end up being removed in favour of batteries.
Another example is the Minn Kota Riptide 101 which is 101lbs thrust. I have one of these and it has amazing grunt. Pulls around 50amps at 36v which is let's say 1.5kw. not a very efficient motor but effective.
Suspect brush less is the way to go partly due to less maintenance ie no brushes.
This is my vocation but I'm not organised enough to get into it properly so it will all remain in my head.
Would love to work in this area but probably not employable anyway !
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Post by Jim on Jun 17, 2021 16:18:36 GMT
An example is the Aquamot 4.3kw pod motor which is 4.3kw (I used my slide rule for that) and rated at 197lbs thrust. Obviously the propeller will make all the difference for a heavy boat but I reckon it is not beyond the wit of man to develop a slow turning sensored brushless motor in a pod with a two blade propeller which will line up with the rudder when not in use. That way you could use the diesel for the main work and switch across to electric as and when. I reckon done right a lot of the diesel engines would end up being removed in favour of batteries. Another example is the Minn Kota Riptide 101 which is 101lbs thrust. I have one of these and it has amazing grunt. Pulls around 50amps at 36v which is let's say 1.5kw. not a very efficient motor but effective. Suspect brush less is the way to go partly due to less maintenance ie no brushes. This is my vocation but I'm not organised enough to get into it properly so it will all remain in my head. Would love to work in this area but probably not employable anyway ! Start your own company, or would you not accept your references?
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Post by thebfg on Jun 17, 2021 16:20:15 GMT
I'll buy your first outboard. Mates rates of course.
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Post by JohnV on Jun 17, 2021 16:31:13 GMT
Peterboat has of course converted his 50+ foot widebam to electric drive and seems to be having good success with it.
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Post by JohnV on Jun 17, 2021 16:40:46 GMT
just to mention, about 45 years ago I built a diesel electric drive for a 72 foot narrowboat, the final version used twin 7.5Hp electric motors belt driving to a conventional shaft and prop via a swashplate hydraulic gearbox. It accellerated well, stopped well and when the bottom was not too close to the top, would maintain 6 Mph. In shallow water the drag used to drop the speed to 3 or 4 Mph.
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Post by Deleted on Jun 17, 2021 16:50:37 GMT
Was it quiet?
Sounds like a potentially rather noisy setup to me.
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Post by peterboat on Jun 17, 2021 17:21:33 GMT
I am currently using the Lynch motor a d135 capable of 26kw I would say that 3.3 kw maintains 3mph in deep water on my widebeam. If it was a narrowboat of the same length about 2kw would achieve 3mph
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Post by JohnV on Jun 18, 2021 8:13:37 GMT
Was it quiet? Sounds like a potentially rather noisy setup to me. It was no noisier than a conventional narrowboat, it used a BMC1800 diesel driving an 18Kw 3 phase generator at 1500 RPM.
Used to get lots of slow down shouters who used to disappear in shame when you stopped and reversed to them without the engine changing note
The reason for the drive method was not because of noise etc but for entirely different reasons caused by trying to keep someone happy.
(eventually proving to be a hopeless endeavour)
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Post by Deleted on Jun 18, 2021 8:24:00 GMT
I am currently using the Lynch motor a d135 capable of 26kw I would say that 3.3 kw maintains 3mph in deep water on my widebeam. If it was a narrowboat of the same length about 2kw would achieve 3mph How much would be needed to push a narrowboat along at 5/6mph in deep water as that is a more normal speed out in the Anglian region.
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Post by Deleted on Jun 18, 2021 8:25:51 GMT
40hp diesel engine..
That's why I like the pod in rudder option because you get to keep your lovely purring go-juice drinker.
I'm the world's no.4 fan of electric boats but I'd still have a diesel or two in anything heavy.
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