Interesting video - Narrowboat with azimuth pod drive

[booke23]

CTC has just posted this. Quite an interesting concept.

 

 

[IanD]

11 hours ago, booke23 said:

CTC has just posted this. Quite an interesting concept.

 

 

 

A clever idea, but a couple of things don't seem to work very well --- the first is the non-intuitive motor speed control method (buttons rather than a lever), but the bigger one is that with the motor running the tiller is very heavy and difficult to move and vibrates a lot, which is exactly what you don't want on an electric drive boat... 😞

Edited October 2, 2023 by IanD

[magnetman]

Judging by the amount of pitting on the drive unit it looks quite an old setup. 

 

Maybe the speed control is just changing voltages rather than a pwm setup. 

 

I would like to have a pod in the rudder in addition to the main diesel engine. To me that is the answer. 

 

There is an electric hire boat on the Wey which I believe has a pod in the rudder but have not seen it out of water. 

 

 

[ditchcrawler]

Just now, magnetman said:

Judging by the amount of pitting on the drive unit it looks quite an old setup. 

 

Maybe the speed control is just changing voltages rather than a pwm setup. 

 

I would like to have a pod in the rudder in addition to the main diesel engine. To me that is the answer. 

 

There is an electric hire boat on the Wey which I believe has a pod in the rudder but have not seen it out of water. 

 

 

Butties have been motorised like that with hydraulic units in the rudder

[magnetman]

Yes Capella and Hampton are examples.

 

 

[David Mack]

I was surprised to see the prop in front of the pod. I would have expected it to be behind (as in an outboard motor). I wonder if the steering would be lighter if the steering axis was in a different position in relation to the motor/propeller.

[IanD]

2 minutes ago, magnetman said:

Judging by the amount of pitting on the drive unit it looks quite an old setup. 

 

Maybe the speed control is just changing voltages rather than a pwm setup. 

 

I would like to have a pod in the rudder in addition to the main diesel engine. To me that is the answer. 

 

There is an electric hire boat on the Wey which I believe has a pod in the rudder but have not seen it out of water. 

 

 

 

It clearly said in the video that this was a variable-speed 3-phase AC drive using PWM...

 

I suspect the problem with pod drives generally is the large forces they exert on the rudder/rotating mechanism; this is fine for a wheel/powered steering setup (where they're normally used) with proper bearings designed to take the stress, but not so good with a tiller, which is the favoured means of narrowboat steering for very good reasons... 😉

[magnetman]

For an ordinary canal boat my idea would be to keep the main engine, two plummer blocks on the tailshaft behind gearbox and run a large low alternator from the shaft to charge the batteries when engine running. 

 

4-7kw pod motor in the rudder with speed control in the tiller bar. 

 

Seamless switch between diesel and electric and you get two separate drivelines for redundancy. 

 

Folding prop could be arranged or a large diameter 2 blade prop which lines up with the rudder when stopped. 

Just now, IanD said:

 

It clearly said in the video that this was a variable-speed 3-phase AC drive using PWM...

 

I suspect the problem with pod drives generally is the large forces they exert on the rudder/rotating mechanism; this is fine for a wheel/powered steering setup (where they're normally used) with proper bearings designed to take the stress, but not so good with a tiller, which is the favoured means of narrowboat steering for very good reasons... 😉

I don't watch youtube videos. 

 

Obviously it would put extra thrust on the rudder but this is not insurmountable. You can have a full length vertical plain bearing like a starn tube. If you need to move the rudder you can just drop the speed orf and allow the boat to do the work. 

 

 

[IanD]

Just now, David Mack said:

I was surprised to see the prop in front of the pod. I would have expected it to be behind (as in an outboard motor). I wonder if the steering would be lighter if the steering axis was in a different position in relation to the motor/propeller.

Given the pod size I expect this would make it vulnerable to damage on a narrowboat, unless the rudder axis was moved forward a lot which means major hull modification.

[David Mack]

1 minute ago, IanD said:

I suspect the problem with pod drives generally is the large forces they exert on the rudder/rotating mechanism; this is fine for a wheel/powered steering setup (where they're normally used) with proper bearings designed to take the stress, but not so good with a tiller, which is the favoured means of narrowboat steering for very good reasons... 

Also a conventional narrowboat rudder shaft is supported at deck level and the skeg, whereas here both bearings are mounted in the 'top hat' above the pod, so all other things being equal, the side loads will be higher.

[IanD]

3 minutes ago, magnetman said:

For an ordinary canal boat my idea would be to keep the main engine, two plummer blocks on the tailshaft behind gearbox and run a large low alternator from the shaft to charge the batteries when engine running. 

 

4-7kw pod motor in the rudder with speed control in the tiller bar. 

 

Seamless switch between diesel and electric and you get two separate drivelines for redundancy. 

 

Folding prop could be arranged or a large diameter 2 blade prop which lines up with the rudder when stopped. 

I don't watch youtube videos. 

 

Obviously it would put extra thrust on the rudder but this is not insurmountable. You can have a full length vertical plain bearing like a starn tube. If you need to move the rudder you can just drop the speed orf and allow the boat to do the work. 

 

 

Which again was exactly what was said in the video that you didn't watch... 😉

 

Having a boat where every time you need to use the rudder you have to drop the power and then turn it back up afterwards kind of defeats a lot of the point of having a pod drive, as well as being a PITA for the steerer...

[magnetman]

Just now, IanD said:

 

Which again was exactly what was said in the video that you didn't watch... 😉

 

Having a boat where every time you need to use the rudder you have to drop the power and then turn it back up afterwards kind of defeats a lot of the point of having a pod drive, as well as being a PITA for the steerer...

 

 

Only a PITA if you don't want to engage with the control of the boat. You could easily mount the speed control for a modern pod drive into the tiller handle at the end. I don't see it being a problem. You could have a twist grip like you get on outboard motors. 

 

The reason I like this idea is it could be retrofitted to boats which already have diesel inboards. 

 

 

 

 

 

 

It would also encourage people to do close quarter manoovering in a more relaxed and controlled manner rather than sticking the tiller over and revving the shit out of the engine. 

 

People could learn how to control boats properly. Vectored thrust at slow speeds is going to be a nice bonus on a canal boat. 

 

 

In fact you would not even need a twist grip. Just a weatherproof 10k pot would probably do it. Little knob sticking out the end you twiddle with your fingers. 

 

 

Or a key fob. 

[IanD]

5 minutes ago, David Mack said:

Also a conventional narrowboat rudder shaft is supported at deck level and the skeg, whereas here both bearings are mounted in the 'top hat' above the pod, so all other things being equal, the side loads will be higher.

And that might be part of the reason for the very heavy rudder if the bearings used were not up to the job -- which I'd be surprised given the aerospace engineering background of the designer.

 

I did toy with the idea of pod drive a couple of years ago, but on further investigation decided it wasn't really suitable for a narrowboat -- too expensive and fragile for canals/locks, and not good with a tiller. For their intended application -- deep-water use in ships like ferries with powered wheel steering where extreme manoeuvrability is vital -- they can be a good solution.

[magnetman]

Floor mounted speed control like a Singer sewing machine might work. 

[IanD]

5 minutes ago, magnetman said:

 

Only a PITA if you don't want to engage with the control of the boat. You could easily mount the speed control for a modern pod drive into the tiller handle at the end. I don't see it being a problem. You could have a twist grip like you get on outboard motors. 

 

The reason I like this idea is it could be retrofitted to boats which already have diesel inboards. 

 

It would also encourage people to do close quarter manoovering in a more relaxed and controlled manner rather than sticking the tiller over and revving the shit out of the engine. 

 

People could learn how to control boats properly. Vectored thrust at slow speeds is going to be a nice bonus on a canal boat. 

 

In fact you would not even need a twist grip. Just a weatherproof 10k pot would probably do it. Little knob sticking out the end you twiddle with your fingers.

 

Or a key fob. 

 

Yes it is, as I've already found without a pod drive... 😉

[Tractor]

The motor, to have a suitable rpm would be 6 or possibly 8 pole. The stator however appears small, there was no mention of power rating, it looked to be no more than 2 or 3kW.

Interesting project, I envy the ability to code the systems.

 

[IanD]

26 minutes ago, ditchcrawler said:

Butties have been motorised like that with hydraulic units in the rudder

They have, but those hydraulic motors are *much* smaller and lighter than the electric motor in the video, so the prop can be in a better position a lot closer to the pivot axis.

Edited October 2, 2023 by IanD

[magnetman]

I meant being able to steer the propeller. You've got one of those 5 pence rudders which isn't the same. 

 

On a short boat having a steerable propeller can be awkward but on a canal boat where the boat is generally formed like a rudder by dint of its shape it would be very nice to have a prop in the rudder as well as the main engine and traditional driveline. 

 

Modern electronically commutated sensored motors seem to be able to 'park' the propeller after stopping so it appears to be possible if one had a two blade propeller specially designed that one would be able to park this behind the rudder when not in use. 

 

The prop would be a bit exposed that is true. 

[Mike Adams]

Please get rid of those stupid fenders. They are going to get caught break off and get stuck in the lock gates etc.

[IanD]

Just now, magnetman said:

I meant being able to steer the propeller. You've got one of those 5 pence rudders which isn't the same. 

 

On a short boat having a steerable propeller can be awkward but on a canal boat where the boat is generally formed like a rudder by dint of its shape it would be very nice to have a prop in the rudder as well as the main engine and traditional driveline. 

 

Modern electronically commutated sensored motors seem to be able to 'park' the propeller after stopping so it appears to be possible if one had a two blade propeller specially designed that one would be able to park this behind the rudder when not in use. 

 

The prop would be a bit exposed that is true. 

 

True -- but it seems able to work pretty much as a stern thruster, with the wash coming out almost at right-angles to the boat and no forward motion, so does the same job. And it's a lot simpler, cheaper and more robust... 😉

[magnetman]

Yes but you don't have a diesel engine directly connected to a propeller. 

 

In my design you would have both and could switch from one to the other whenever you like. 

 

In a series hybrid, which is a Good Idea, there is no way to connect the diesel engine to the propeller in the event of electrical problems. Eggs in one basket. 

 

I'm proposing a third way to do it which can be retrofitted to boats which already have a diesel engine connected to its own propeller. 

 

 

 

 

You leave the existing installation alone - apart from adding a beefy alternator to the tail shaft - and add a new rudder assembly with the pod in it and uprated bearings and a battery bank. 

 

 

With this arrangement you could cruise between locks on electric if it is a nice day and no motorway madness types are trying to get their gas lockers into your back cabin or diesel if you want to move. Once you get close to moveable structures the diesel engine gets switched orf and slow close quarters manoovering happens with the electric. 

 

All the while you have two independent propulsion systems. 

 

A bit of tweaking and some back of envelope drawings jobs done innit. 

 

 

[IanD]

27 minutes ago, magnetman said:

Yes but you don't have a diesel engine directly connected to a propeller. 

 

In my design you would have both and could switch from one to the other whenever you like. 

 

In a series hybrid, which is a Good Idea, there is no way to connect the diesel engine to the propeller in the event of electrical problems. Eggs in one basket. 

 

I'm proposing a third way to do it which can be retrofitted to boats which already have a diesel engine connected to its own propeller. 

 

You leave the existing installation alone - apart from adding a beefy alternator to the tail shaft - and add a new rudder assembly with the pod in it and uprated bearings and a battery bank. 

 

With this arrangement you could cruise between locks on electric if it is a nice day and no motorway madness types are trying to get their gas lockers into your back cabin or diesel if you want to move. Once you get close to moveable structures the diesel engine gets switched orf and slow close quarters manoovering happens with the electric. 

 

All the while you have two independent propulsion systems. 

 

A bit of tweaking and some back of envelope drawings jobs done innit. 

 

 

A series hybrid has no propulsion if the drive fails, just like a diesel boat doesn't if the engine fails -- which given things like dirty fuel problems is not exactly rare, going by postings on CWDF and elsewhere...

 

Tweaking and back-of-envelope drawings all sounds fine until you have to make it work in practice, as the video shows... 😉

 

A prop and rudder steered by a tiller is the almost-universal choice for narrowboats for many good reasons, regardless of what drives the prop or even what kind of rudder it is. A more complicated system just to get propulsion redundancy doesn't seem like a good tradeoff to me, but if you want to try it out then I'd be interested to hear your results.

Edited October 2, 2023 by IanD

[magnetman]

I don't think you are taking me seriously enough Sir. 

[IanD]

45 minutes ago, magnetman said:

I don't think you are taking me seriously enough Sir. 

No, I think you're trying to solve a problem that doesn't really exist with a bodge solution that isn't properly thought through... 😉

Edited October 2, 2023 by IanD

[magnetman]

I realise that is what you think.

 

However in a real situation where someone has a diesel engine installed and does not want to remove it there are not all that many ways to get electric propulsion..

 

I also considered having a pod each side of the uxter plate on retractable mounts with tubes to deck level fir servicing and prop cleaning. You could wind them up and down or use actuators. 

 

I spend most of my time in an 18ft electric canoe which I have put a trolling motor on the back of and steer with strings so I know about quiet electric boating. Its great but best to keep the diesel engine on a heavy boat. Diesel-gearbox-prop is actually very reliable. Yes one gets fuel issues but this is a sign of neglect not a design feature. Use a day tank and have good filters. 

 

Wing engines in the form of pod motors may be a better solution than a udder mounted pod. 

 

I haven't seen the video but in the image shown it appears too complex as the pod is separate but seems to be steerable. 

 

That is definitely overcomplicating things. 

 

 

Edited October 2, 2023 by magnetman