Electric propulsion with generator ?

[waterworks]

Anyone know anything about a set up for a 60 ft NB with an enclosed AC Diesel  generator and electric motor propulsion ?

 

How big a generator ?

Single or 3 phase ?

What kind of motor ?

[Alan de Enfield]

Why ?

 

What is the difference to running a diesel engine turning a shaft ?

 

Would runing an electric motor off a generator qualify you as an 'electric propulsion' boat ? I don't think you would get the electric boat licence discount without their being some batteries in between the electic generation and the motor.

Edited May 8 by Alan de Enfield

[matty40s]

There are many good diesel engines which drive a narrowboat without having to waste energy by converting it into electric first.

[mrsmelly]

3 minutes ago, Alan de Enfield said:

Why ?

 

What is the difference to running a diesel engine turning a shaft ?

Cost. It's much more expensive to add in electric motors oh and of course more complex than a simple gearbox bolted to the diesel engine. What's not to like 😉

[LadyG]

I believe  the cocooned generators are rather expensive, and to design the boat around one would add significantly to the cost, of course.

I would worry about the complexity.  Someone with a practical. background in electrical engineering might actively seek a challenge, but to a greater or lesser extent it looks as tbough we  are still at the late innovation stage. 

I dont know if a genset would be unobtrusive to the boater himself,  or to other boaters (it can be extremely irritating having someone moor near you at 4.00pm and then continue to run a generator of any description).

I assume the plan is to have the boat driven by electric motor,  the main benefit would be silent cruising.

I think you would be best advised to discuss in detail with  a specialist  fitter.

Solar energy is free only if you ignore the ccosts, but has to be greener than diesel 😉

 

 

 

 

Edited May 8 by LadyG

[Onewheeler]

I've long considered this a good approach if I needed to re-engine a boat (it would be nice on the French boat but we'll be selling it first). A generator plus electric propulsion enables you to charge off shore power or solar as an alternative to fossil fuel. In the UK outside marinas shore power is in short supply. In France it's very common and often free so running most of the time without diesel is feasible.

[Alan de Enfield]

5 minutes ago, Onewheeler said:

I've long considered this a good approach if I needed to re-engine a boat (it would be nice on the French boat but we'll be selling it first). A generator plus electric propulsion enables you to charge off shore power or solar as an alternative to fossil fuel. In the UK outside marinas shore power is in short supply. In France it's very common and often free so running most of the time without diesel is feasible.

 

But are you talking about having batteries between the generator and the motor ?
The OP sounds as if he is planning to just 'plug' the motor directly into the Genny. (Presumably he'll need a 48v (?) generator).

[Onewheeler]

2 minutes ago, Alan de Enfield said:

 

But are you talking about having batteries between the generator and the motor ?
The OP sounds as if he is planning to just 'plug' the motor directly into the Genny. (Presumably he'll need a 48v (?) generator).

Yes. Probably the same sort of size battery pack as for a car, maybe a bit less as you can charge as you travel. Most canal journeys use minimal power to the prop, especially as half the time is spent in locks. Rivers might need continuous electrical power from a generator, but for a typical narrowboat 20 kW would probably do.

[BEngo]

For a pure diesel electric set up I would investigate a 3 phase generator, variable frequency drive and 3 phase motor.  Its probably going to have to be 415 V so well out of the LV region and will want some proper design work, but should be much more efficient than typical battery hybrid systems.

 

N

[IanD]

37 minutes ago, BEngo said:

For a pure diesel electric set up I would investigate a 3 phase generator, variable frequency drive and 3 phase motor.  Its probably going to have to be 415 V so well out of the LV region and will want some proper design work, but should be much more efficient than typical battery hybrid systems.

 

N

 

There's little point for a canal boat having diesel-electric drive -- it's used on railway locos (with a lot of added weight and complexity) to enable high starting torque and maximum power at a wide range of wheel speeds, but a boat doesn't need this because a prop absorbs very little power at low rpm.

 

Once you add a big LFP battery bank and solar (series hybrid boat) the picture changes because as well as lower fuel consumption (can even be zero in summer if you don't move all day every day) you get silent cruising a lot of the time, which is *brilliant*... 🙂 

 

But it makes no economic sense due to the high cost of a cocooned generator and electrics, it's currently (see what I did there?) a luxury solution for those with deep pockets who value silence... 😉 

Edited May 8 by IanD

[cuthound]

48 minutes ago, BEngo said:

For a pure diesel electric set up I would investigate a 3 phase generator, variable frequency drive and 3 phase motor.  Its probably going to have to be 415 V so well out of the LV region and will want some proper design work, but should be much more efficient than typical battery hybrid systems.

 

N

 

The IEC definition of low voltage is less than 1,000 volts AC or 1,500 volts DC, and is the basis of the IET definition used in the UK.

 

IEC Definition[edit]

Voltage range	AC RMS voltage (V)	DC voltage (V)	Defining risk
High voltage (HV)	> 1000[1]a	> 1500[1]a	Electrical arcing
Low voltage (LV)	≤ 1000[1]a	≤ 1500[1]a	Electrical shock

 

 

United Kingdom[edit]

• British Standard BS 7671, Requirements for Electrical Installations. IET Wiring Regulations,^[3] defines supply system low voltage as:

exceeding 50 V ac or 120 V ripple-free dc. but not exceeding 1000 V ac or 1500 V dc between conductors, or 600 V ac or 900 V dc between conductors and earth.

The ripple-free direct current requirement only applies to 120 V dc, not to any dc voltage above that. For example, a direct current that is exceeding 1500 V dc during voltage fluctuations it is not categorized as low-voltage.

Edited May 8 by cuthound
Clarification

[Alan de Enfield]

The ISO specification for boat wiring : ISO 13297:2020 quotes

 

This document specifies the requirements for the design, construction and installation of the following types of DC and AC electrical systems, installed on small craft either individually or in combination:

a) extra-low-voltage direct current (DC) electrical systems that operate at nominal potentials of 50 V DC or less;

b) single-phase alternating current (AC) systems that operate at a nominal voltage not exceeding AC 250 V.

This document does not cover the following:

— electrical propulsion systems of direct current less than 1 500 V DC, single-phase alternating current up to 1 000 V AC, and three-phase alternating current up to 1 000 V AC, which are addressed by ISO 16315;

 

 

For "propulsion" electics ISO 16315  states :

 

Edited May 8 by Alan de Enfield

[IanD]

12 minutes ago, Alan de Enfield said:

The ISO specification for boat wiring : ISO 13297:2020 quotes

 

This document specifies the requirements for the design, construction and installation of the following types of DC and AC electrical systems, installed on small craft either individually or in combination:

a) extra-low-voltage direct current (DC) electrical systems that operate at nominal potentials of 50 V DC or less;

b) single-phase alternating current (AC) systems that operate at a nominal voltage not exceeding AC 250 V.

This document does not cover the following:

— electrical propulsion systems of direct current less than 1 500 V DC, single-phase alternating current up to 1 000 V AC, and three-phase alternating current up to 1 000 V AC, which are addressed by ISO 16315;

 

Which is why (almost?) all the builders who professionally install hybrid systems use 48V (nominal) batteries, so everything in the electrical area (propulsion, inverter, batteries, busbars, shunts, isolators, PWM controller, MPPT outputs...) is then classed as ELV and has very simple shielding/insulation/safety requirements.

 

Yes there's a separate category for propulsion systems at much higher voltage/power (e.g. bigger boats/ships), but this has far more stringent requirements -- as would be expected.

 

I'm sure @Peterboat will pop in to say that his higher-voltage (72V?) DIY system passed BSS inspection so it must be OK. My guess is that the inspector wasn't aware of the detailed ELV requirements, and after a quick look said "yeah, that's OK" -- which isn't the same as it being 100% legal if an inspector is being picky, which is what professional installers will be concerned about... 😉 

Edited May 8 by IanD

[cuthound]

30 minutes ago, IanD said:

 

Which is why (almost?) all the builders who professionally install hybrid systems use 48V (nominal) batteries, so everything in the electrical area (propulsion, inverter, batteries, busbars, shunts, isolators, PWM controller, MPPT outputs...) is then classed as ELV and has very simple shielding/insulation/safety requirements.

 

Yes there's a separate category for propulsion systems at much higher voltage/power (e.g. bigger boats/ships), but this has far more stringent requirements -- as would be expected.

 

I'm sure @Peterboat will pop in to say that his higher-voltage (72V?) DIY system passed BSS inspection so it must be OK. My guess is that the inspector wasn't aware of the detailed ELV requirements, and after a quick look said "yeah, that's OK" -- which isn't the same as it being 100% legal if an inspector is being picky, which is what professional installers will be concerned about... 😉 

 

With higher voltage battery systems (>50v DC), it is usual to prevent casual access to them, so that no one can get to them without tools or appropriate keys and common to interlock the access with a system to open circuit breakers to restrict each section of the battery to sections of 50 volts or less so that you don't need people trained on HV systems to maintain them.

[IanD]

Just now, cuthound said:

 

With higher voltage battery systems (>50v DC), it is usual to prevent casual access to them, so that no one can get to them without tools or appropriate keys and common to interlock the access with a system to open circuit breakers to restrict each section of the battery to sections of 50 volts or less so that you don't need people trained on HV systems to maintain them.

 

True -- but this doesn't just apply to the batteries, it applies to everything connected to them, the entire electrical system. And splitting the batteries doesn't help for any of the equipment (and connections to them) that runs off the higher voltage series connection... 😞 

 

Given that most boat maintenance s done by the (non-HV-trained) owners, locking them away isn't going to be very helpful either in practice -- and it also opens up the boatbuilder to liability if the access precautions are not secure enough or bypassed. HV training is already a big issue for garage mechanics working on EVs using 400V/800V systems, as well as the vehicle manufacturer who has to make sure everything is safe even against idiots...

[cuthound]

1 minute ago, IanD said:

 

True -- but this doesn't just apply to the batteries, it applies to everything connected to them, the entire electrical system. And splitting the batteries doesn't help for any of the equipment (and connections to them) that runs off the higher voltage series connection... 😞 

 

Given that most boat maintenance s done by the (non-HV-trained) owners, locking them away isn't going to be very helpful either in practice -- and it also opens up the boatbuilder to liability if the access precautions are not secure enough or bypassed. HV training is already a big issue for garage mechanics working on EVs using 400V/800V systems, as well as the vehicle manufacturer who has to make sure everything is safe even against idiots...

 

All of the high voltage  DC equipment I have seen won't work without the batteries connected.

 

I cant see any boat producer using anything other then ELV systems for the reasons you give because the production volumes are too low. With cars it makes sense for the manufacturer to use higher voltages because the weight penalty of using lower voltage systems will be even greater and of course it locks the maintenance into the dealerships.

[IanD]

10 minutes ago, cuthound said:

 

All of the high voltage  DC equipment I have seen won't work without the batteries connected.

 

I cant see any boat producer using anything other then ELV systems for the reasons you give because the production volumes are too low. With cars it makes sense for the manufacturer to use higher voltages because the weight penalty of using lower voltage systems will be even greater and of course it locks the maintenance into the dealerships.

 

It's not just the weight penalty, it's the sheer impracticability (and cost!) of having 100kW+ systems running on 50V due to the massive currents involved (thousands of amps) and the much higher losses in all components, especially controllers and cables. It's why more and more cars are moving from 400V to 800V, cable sizes drop by a factor of 4 and ultrafast low-loss charging becomes much easier, partly driven by the advent of modern high-voltage electronics like SiC which can switch these voltages with very low losses.

 

It doesn't lock maintenance into the dealerships, but it does lock it into workshops (which can still be independent) with HV-qualified mechanics and equipment.

 

None of which applies to canal boats at power levels of tens of kW, which as you say is why they all use ELV systems -- at least, those professionally supplied and/or installed as opposed to DIY... 😉 

Edited May 8 by IanD

[Sea Dog]

8 hours ago, waterworks said:

Anyone know anything about a set up for a 60 ft NB with an enclosed AC Diesel  generator and electric motor propulsion ?

 

How big a generator ?

Single or 3 phase ?

What kind of motor ?

Try the folks at Beta Marine. They offer a number of hybrid setups - a quick chat may reveal whether any are suitable for you and your boat.

[john.k]

Typically,you can buy secondhand a 25KVA 3p diesel genset for around what a dealer would want for a used bare motor............a 3p TEFC motor can be found for a little over scrap price.............the speed controll would have to be  new ,but a keen hobbyist could certainly build one with components from China...........as mentioned ,you do have to be a bit careful with 415V ..............I know someone who replaced all the DC electrics in a Coles crane with 3p 415v ,but it wasnt a success ...........the Coles DC system is very sophisticated for something designed pre WW2 

[IanD]

10 hours ago, john.k said:

Typically,you can buy secondhand a 25KVA 3p diesel genset for around what a dealer would want for a used bare motor............a 3p TEFC motor can be found for a little over scrap price.............the speed controll would have to be  new ,but a keen hobbyist could certainly build one with components from China...........as mentioned ,you do have to be a bit careful with 415V ..............I know someone who replaced all the DC electrics in a Coles crane with 3p 415v ,but it wasnt a success ...........the Coles DC system is very sophisticated for something designed pre WW2 

But why on earth would you want to? All you're doing is replacing a propshaft with a large/heavy/expensive 3ph generator (inside the genset) and 3ph motor, and you don't even get any ability to vary the prop speed since both are synchronous and the generator is fixed rpm... 😞 

 

For a variable speed prop drive from a fixed speed generator -- which is what you would need for a boat -- you need the link between the two to effectively be DC, and either a DC (e.g. Lynch) or brushless PMAC/induction motor/controller (most newer designs). Which means either an AC generator plus charger to convert to DC, or a DC generator. And once you do this, you might as well add a battery bank so you don't need to run the generator all the time, and an inverter to generate onboard 230Vac -- oh look, a series hybrid boat.... 😉

[john.k]

typically ,speed controll would be by a VFD .........however ,back in the day ,you could get two speed AC motor and even four speed AC motors..............im not saying Id do it .....but that is what the OP is asking.

[ditchcrawler]

Some years back there was one at Napton Narrowboats 

 

From CanalPlanac

Baud Maud Built by Mel Davis Boats - Length : 18.29 metres ( 60 feet ) - Beam : 2.08 metres ( 6 feet 10 inches ) - Draft : 0.55 metres ( 1 foot 10 inches ). Metal hull N/A Electric power of 999 HP. Registered with Canal & River Trust number 500962 as an Electric Motor Boat.  ( Last updated on Wednesday 22nd May 2013 )

[BoatinglifeupNorth]

 

6 minutes ago, ditchcrawler said:

Some years back there was one at Napton Narrowboats 

 

From CanalPlanac

Baud Maud Built by Mel Davis Boats - Length : 18.29 metres ( 60 feet ) - Beam : 2.08 metres ( 6 feet 10 inches ) - Draft : 0.55 metres ( 1 foot 10 inches ). Metal hull N/A Electric power of 999 HP. Registered with Canal & River Trust number 500962 as an Electric Motor Boat.  ( Last updated on Wednesday 22nd May 2013 )

 that must of been one big electric motor and battery bank, 999Hp👍

Edited May 17 by BoatinglifeupNorth

[john.k]

There is a utube of replacing an electric  propulsion motor on a ship by cutting a big hole in the side ........IIRC the motor is around 15,000hp.

[ditchcrawler]

17 hours ago, john.k said:

There is a utube of replacing an electric  propulsion motor on a ship by cutting a big hole in the side ........IIRC the motor is around 15,000hp.

I have seen that done with ships bow thruster motors but they were diesels