Hi James,

I have been looking at this topic myself for a while now.

When you say all electric do you mean for all needs , propulsion, heating, cooking? if so it will be difficult to achieve but not impossible.

My own research has left me with this as a best option.

Hybrid drive, diesel electric, using a large battery bank 48 V x 800 amps and a 40 + hp diesel, then adding a large solar array to charge the batteries.

Two companies are in the market for diesel hybrids, hybrid marine and thames electric boat, at least if you stick to UK based companies.

Any number of companies will supply you with solar panels.

Typical usage for narrowboat hybrid propulsion is 1 hour diesel and 1 hour electric drive if you have no other means of generating electricity.

This depends very much on your cruising speed though.

You need approximately 1 kw per hour to drive your boat at low speeds and 4 kw for higher speeds.

Most diesels are fitted with alternators of between 5 and 10 kw.

However if you can make the power required using solar panels as I plan to you can just possibly not need the diesel at all.

It is possible to fit between 2 and 4 kw of solar panels on the roof of a narrow boat.

As a guide 3 kw of panels average 2500 kw per year in the UK (mounted on a house) divide that by 365 and you get 6.8 kw per day.

Of course cloudy days in winter might only make 1 kw and sunny summer days 12 kw depending on your location with regard to shade and angle to the sun etc. and  a narrowboat does not get the ideal position for solar collection most time anyway.

I am hoping to average 4 kw per day over the year.

I live purely on solar power at home (10 years now) and we use around 6 kw per day, so if you take that away from whatever your panels make in a day then that is what is left for your propulsion.

You see the difficulty.

My daily home usage is high admittedly and when economising we can get by on 2 kw but we use gas for cooking and wood for heating.

At an absolute minimum it might be possible to just to run a fridge and a few led lights and get by on less than 1 kw per day.

You can of course stop at almost any marina overnight and charge your battery bank from the shore supply. Doing this to to top off your batteries is eminently possible. Don’t forget though you will need to pay an overnight mooring fee plus a charge for you electricity usage.

My decision is to go with the diesel hybrid with solar power because :- while I hope to manage without using a diesel engine ‘it is better to have and not need than need and not have’.

There are times when the power from an electric motor will not be enough, normally 10 kw is the maximum if you need more then a diesel will give you around 35 kw. Think rivers here.

In periods of prolonged cloudy weather you might end up with empty batteries but the diesel will charge them for you if needed.

Then use gas for cooking and coal/wood for heating. To keep a narrowboat warm in winter you need around 4 kw of heat per hour and think what that will do to your batteries.

The less you discharge your battery bank the longer they will last.

Some battery types are better than others but very basically think of it this way :- your battery is rated at 800 amps its typical lifetime output will be 80,000 amps this can be 100 days at 800 amps or 1,000 at 80 amps. (note this a guide only and figures are purely representative)

Hope that is clear.

Some batteries i.e. gel batteries can manage as many as 6,500 cycles they say, but the small print will tell you this is at less than 10% discharge per cycle.

So the bigger your battery bank the better but remember they are very heavy, a typical 48 v 800 amp set will be nearly 1,500 kgs.

The newer lithium batteries are less than 1/2 the weight but they cost 4 x as much. 

My house battery set if not discharged by more than 20 % per day should last me 15 years.

The set for a typical narrowboat installation is twice as big, using 1 kw @ 48 v you get 20 amps so 8 hours slow propulsion = 160 amps which allowing for losses in efficiency is your probable daily maximum usage of the battery bank to ensure long battery life .  

Of course add on your domestic usage and you see the problem.

My current solar array is 1.68 kw at 48 v and I am very happy using an Outback mppt fm60 charge controller for my 24 v 880 amp lead acid traction 2 v cells tubular batteries and a Victron 24/3000/70 combined inverter charger to supply the house 230 v electrics. 

Hope this might give you some thoughts on the matter.

Martin.

Your very welcome James.

Who knows if you get your boat built before me I will be the one picking your brains.

Martin.

Hi Gm,

Not really the point though having a diesel powered generator to run an all electric boat though is it?

Might as well just run a diesel direct to the prop.

Afraid I cannot see the added value of running a diesel generator for electric propulsion, yes I know the QM 2 does but that is a difference of scale.

The quietest diesel generator I have found is the Victron Whispergen which is basically a Sterling external combustion engine which you might look at for your idea though.  It also generates a lot of heat which can be used for heating in the winter.

Martin. 

I confess I had forgotten about the electric boat license discount scheme.

The Paguro certainly sounds (pardon the pun) a good option and at 49 db’s is indeed very quiet, although 0.35 liters of fuel per kw/hour will still give you a hefty fuel bill.

I wonder if anyone reads this and uses one.

If you do get it installed be sure and let us know how it works out for you.

Martin.

Hi GM,

That is 0.35 ltr for every kw hour, not for all your needs.

If you have your 3 kw oven on for an hour that is 1.15 ltr, or at 4 mph around 1.4 ltr per hour (based on GF’s figures) personally I think it will be more, just for the propulsion. Working out the extra for conversion losses is more problematic.

Your electrical heating at 4 kw per hour for 24 hours a day = 33.6 ltr if solely provided by your generator in winter.

Not forgetting the generators efficiency at low loads is very poor and you will likely need it on for at least 14 hours a day if you use electricity for all your needs.

Your ordinary diesel propulsion unit will also generate electricity for you with very little extra fuel consumed.

Think about the diesel hybrid packages, roughly 1/2 the costs for your diesel usage over a year and you get heating/hot water from it too.

There is some good information at  http://www.hybrid-marine.co.uk

Also I have seen (a blogger of many years experience) who states that even a 34 hp (25 kw) engine is barely able to cope on rivers when they are flowing well, hence my preference for the diesel engine hybrid utilising a 43 hp engine.

With regards to gas free boating by the way, we use gas for our cooking here at home and a 19 kg gas bottle will last between 3 and 4 months, not sure of the prices of gas in the UK but I expect it will be cheaper than the electricity alternative. 

Just don’t try to use gas for your heating, a 19 kg gas bottle lasts about 3 days, gulp. That cost me about £30 while wood for the same time cost £10.

There is a lot to consider.

Millburn boats, Braidbar boats and MGM boats have all fitted out diesel hybrids in the past few years, they might be able to offer some advice.

Martin.

Hi GM, That is 0.35 ltr for every kw hour, not for all your needs. If you have your 3 kw oven on for an hour that is 1.15 ltr, or at 4 mph around 1.4 ltr per hour (based on GF’s figures) personally I think it will be more, just for the propulsion. Working out the extra for conversion losses is more problematic. Your electrical heating at 4 kw per hour for 24 hours a day = 33.6 ltr if solely provided by your generator in winter. Not forgetting the generators efficiency at low loads is very poor and you will likely need it on for at least 14 hours a day if you use electricity for all your needs.   Your ordinary diesel propulsion unit will also generate electricity for you with very little extra fuel consumed. Think about the diesel hybrid packages, roughly 1/2 the costs for your diesel usage over a year and you get heating/hot water from it too. There is some good information at http://www.hybrid-marine.co.uk Also I have seen (a blogger of many years experience) who states that even a 34 hp (25 kw) engine is barely able to cope on rivers when they are flowing well, hence my preference for the diesel engine hybrid utilising a 43 hp engine.   With regards to gas free boating by the way, we use gas for our cooking here at home and a 19 kg gas bottle will last between 3 and 4 months, not sure of the prices of gas in the UK but I expect it will be cheaper than the electricity alternative.  Just don’t try to use gas for your heating, a 19 kg gas bottle lasts about 3 days, gulp. That cost me about £30 while wood for the same time cost £10.   There is a lot to consider.   Millburn boats, Braidbar boats and MGM boats have all fitted out diesel hybrids in the past few years, they might be able to offer some advice. Martin.

Martin,

I would not use Electric for heating, diesel is more economical for that. The reason for getting rid of gas is that it is the most dangerous fuel on the boat and causes the most headache when the BSS comes round. Cooking could be diesel or electric. The 0.35 litre figure was yours from your post, have not done any figures recently. From memory propulsion should have been cheaper taken over the year, remembering the input from the solar panels and the occasional shoreline when in the marina.

Problem with hybrids is I don’t think they qualify for the license discount.

Ah it is but a dream until I find the money.

I remember reading an introduction to sailing book written in the early 80’s. The writer stated it was only a matter of time before bottled gas was outlawed on boats due to the poor safety record in its use. Here we are 35 years on though and its still the favoured fuel for cooking on boats and is often used for heating water and/or boat itself. 

The safety regimes developed over the years obviously work. I can’t imagine any professional installation being unreliable as long as routine maintenance including replacement of perishable hoses, is undertaken. No great difference from other maintenance work on a boat.

Regarding electric propulsion on boats. Whilst it appeals in concept to many, the practicalities of obtaining the substantial electrical power explain why its still a rare sight on any vehicle including canal boats. A hybrid diesel/electric system seems the best solution at present. A recent trip on a hybrid bus indicated how the diesel engine runs, when required, at its most efficient speed. The kinetic energy savings during braking on this and similar automotive applications are easily seen as well, but I don’t see how such savings can be gleaned from a canal boat.

Hi Both,

One of the things that became apparent having cruised both an electric and a diesel boat is the amount of time the diesel just sits running doing nothing, or is running in its lowest efficiency area. I reckon that is something of about 50% of the time. A good DC motor runs at near its max efficiency throughout it power ran, plus at locks etc it uses no power but is immediately available.

The diesel/electric hybrid where the diesel is used directly for drive to me just does not seem the right answer.

Niaid, a 60 footer with a 14KW Lynch motor gear down by about 4:1 handled the Thames with no problems. In trials she had over 95% of the power of a diesel boat of a similar size. Gearing and the correct prop are part of the secret.

Additionally I don’t think the hybrid qualifies for the discount the electrically propelled boat does.

Re gas, while I agree about maintenance, if I can remove it economically the boat will be a safer boat and having the power available either a diesel or an electric cooker makes sense to me..:)