Real-life energy usage on electric/series hybrid narrowboat with solar and generator

[nicknorman]

23 minutes ago, IanD said:

 

I agree that seems like it should work at first glance. But unlike a generator a standard diesel engine is not turned on and off on demand (and in relatively short bursts) by an external controller, and I guess in your case you also didn't have similarly (but separately) controlled boiler and motorised valves in the CH circuit. Getting two separately (and automatically) controlled systems to play together nicely -- even if only linked thermally by a heat exchanger, not sharing bodily fluids -- is by no means a trivial task, and after discussing this with Ricky I decided that the possible benefits were too small to justify the time and effort to make sure everything worked properly in a linked system.

 

Not saying it can't be made to work, but we decided against it. For example we often want the heating and hot water to come on before 8am so can't run a generator, and most commonly want heating after 8pm when the same applies. For other people with different systems and lifestyles a linked system might work very well... 😉 

We have 2 feeds to our radiators / calorifier circuit, the Mikuni and the plate heat exchanger from engine skin tank circuit. Each pump feeds via a low pressure 1 way valve so that you can turn on one, or the other, or both, and there is no back-flowing through the inoperative circuit. Completely transparent and foolproof and simple.

[David Mack]

22 hours ago, IanD said:

-- Average drive power when travelling (cruising + moored boats + locks) was 2.3kW -- 11.7kWh/day at 5hrs/day, 1.3kWh/mile

-- Domestic energy use averaged 3.7kWh/day, dependent on activity and cooking/washing (2.0kWh-6.0kWh range), so about a third of propulsion power

-- Total energy use (solar+generator+shoreline) averaged out at 17kWh/day

So what makes up the difference between 11.7 + 3.7 and 17?

[Alan de Enfield]

14 minutes ago, David Mack said:

So what makes up the difference between 11.7 + 3.7 and 17?

 

Did he not explain that earlier as "inneficiences in the system, losses, etc" ?

 

ie the AC to DC converson is only 88% efficient.

 

Generator was running 50% of travel time - so there is 1Kwh 'lost'

Edited September 14 by Alan de Enfield

[David Mack]

14 minutes ago, Alan de Enfield said:

 

Did he not explain that earlier as "inneficiences in the system, losses, etc" ?

 

ie the AC to DC converson is only 88% efficient.

 

Generator was running 50% of travel time - so there is 1Kwh 'lost'

So the total energy use of 17 kWh/day is not "use" it is "input"?

[Alan de Enfield]

Just now, David Mack said:

So the total energy use of 17 kWh/day is not "use" it is "input"?

 

That is how I read it, but I'm sure Ian will be along shortly.

[IanD]

1 hour ago, David Mack said:

So the total energy use of 17 kWh/day is not "use" it is "input"?

It's the amount of energy I needed to supply, for both domestic and propulsion use and conversion losses, which is what matters since this determines fuel use.

 

Such losses often get ignored, making things look better than they actually are -- for example if you want to end up with 2kW at the propeller you need about 2.5kW from the generator by the time all the charger/controller/motor losses are included. So a 25% efficient generator (fuel in to AC out) is only about 20% efficient when the energy is used for propulsion  (fuel in to prop power).

 

Which is actually similar to a diesel engine at cruising power. So the real fuel savings with a hybrid come from lower consumption at lower speeds and in locks, the fact that solar contributes part of the required energy, and that domestic power generation is at least twice as efficient as using alternators for battery charging.

 

None of which really bothers me, because fuel saving wasn't the reason I went hybrid. But it seems that many people considering -- or even promoting -- hybrid/electric boats are being rather optimistic about efficiency and energy savings, which is why I wanted to post some real numbers taken over a year instead of cherry-picking to make things look better than they really are.

 

I'm still pleased with the boat though, it's doing what I wanted it to -- albeit with lower solar yield and more genny running than I expected... 🙂

Edited September 14 by IanD

[jim mitchell]

On 13/09/2024 at 11:25, IanD said:

There's a lot been said about this subject with lots of figures bandied around about how little (or much!) energy is needed/used by boats like this, so I thought I'd provide some actual numbers logged over the last year or so (50 days total cruising time) for my boat to counter some perhaps over-optimistic assumptions... 😉

Ian, thank you for the very honest post - re your seriel hybrids performance.

may i ask/ check is your motor 48VDC or 240AC supplied - i appreciate your reasons for going 'your way' but when designing the boat was operating the genny 'full time' when cruising considered ?

I.e. use a 240v genny to 240v motor via quattro  such that a smaller genny (maybe 4kw) ran continuous feeding the motor when moving and charging domestics when stationary (locks) and 50/50 when passing boats.

 

I ask because the heat you refer to in the electric cupboard and temperature resticting the charge rate would seem to indicate that some energy is being wasted as heat - would a reduced charging rate improve this ?

The quiet burbling of the prop also suggests less than optimum drive - although i am well aware of the difficulties /limits on prop effeciency at varying speeds.

 

Noise wise from a genny - is not easy to limit but as (IIRC) perseverance used quarter wave noise reduction quite sucessfully and i am less clear if anyone has fully attempted to silence a genny package - the best i have found (as manufactured rather than home modied) gave a figure of  around 55dB - certainly not silent but far from noisy too.

[Melbourne_Boaters]

Ian,
Thanks for sharing - nice to see real world data - even if it is a little lower than hoped?  How hopeful are you that better cooling of the Quattro will lift power into the batteries?  Is the generator oversized vs what you can hope to get through the Quattro in real world conditions?

[IanD]

9 hours ago, Melbourne_Boaters said:

Ian,
Thanks for sharing - nice to see real world data - even if it is a little lower than hoped?  How hopeful are you that better cooling of the Quattro will lift power into the batteries?  Is the generator oversized vs what you can hope to get through the Quattro in real world conditions?

 

I'm sure that better cooling will help -- at the moment there's one fan (140mm 2000rpm Noctua) blowing cold air from outside into one end of the cabinet, with an exhaust duct from the other end (next to the Quattro) to outside. However the cabinet doors are not airtight, so when the generator is running some of the cooling air will escape into the stern space, and the hot air outflow will be reduced. I'm going to add another cooling fan to suck air out of the exhaust duct, I estimate this will more than double the rate that hot air is extracted from the Quattro and drop the temperature rise by more than 50%, which should be enough. If this is still not enough (especially at higher loads, see below) then I can swap the fans out for 3000rpm models which are noisier and consume more power but have about 50% higher airflow.

 

Thought the Quattro is set to have charging controlled by the external BMS -- and the limit here is set to 420A, or 210A above 95% SoC -- it seems that it still takes the lower of this and the internal Quattro limit, which was set to 110A, hence the maximum current I was seeing. I've now put this up to the maximum 140A, but I'm pretty sure the extra fan will then be needed since it will run hotter.

23 hours ago, jim mitchell said:

Ian, thank you for the very honest post - re your seriel hybrids performance.

may i ask/ check is your motor 48VDC or 240AC supplied - i appreciate your reasons for going 'your way' but when designing the boat was operating the genny 'full time' when cruising considered ?

I.e. use a 240v genny to 240v motor via quattro  such that a smaller genny (maybe 4kw) ran continuous feeding the motor when moving and charging domestics when stationary (locks) and 50/50 when passing boats.

 

I ask because the heat you refer to in the electric cupboard and temperature resticting the charge rate would seem to indicate that some energy is being wasted as heat - would a reduced charging rate improve this ?

The quiet burbling of the prop also suggests less than optimum drive - although i am well aware of the difficulties /limits on prop effeciency at varying speeds.

 

Noise wise from a genny - is not easy to limit but as (IIRC) perseverance used quarter wave noise reduction quite sucessfully and i am less clear if anyone has fully attempted to silence a genny package - the best i have found (as manufactured rather than home modied) gave a figure of  around 55dB - certainly not silent but far from noisy too.

 

All motors are DC-supplied (though nowadays they're usually driven by a complex variable-speed/voltage/frequency 3-phase AC motor controller), so your idea doesn't work... 😞 

 

The other solution is to use a 48V DC generator, but there are several minus points with this -- one is that they are few and far between and expensive, a second is that it's more difficult to control the charging especially with LFP batteries with a very flat SoC-voltage curve, it needs heavy cables and has to be close to the battery bank, and if the Quattro ever fails you have no AC power (which runs most things) on the boat at all -- with an AC generator you can run directly from this while waiting for a repair.

 

The heat generated when charging is similar to the heat generated when driving heavy domestic loads (cooking, washing) so needs to be dealt with anyway -- in fact it's probably less since the maximum AC output is higher than the charging power. This can definitely be improved now I've realised what the problem is -- which wasn't obvious until I put a RuuviTag sensor inside the electrical cupboard a couple of months ago.

 

I don't think there's any prop noise issue, you always get this but it's much less obvious on a diesel boat. The setup I have (14kW/1080rpm motor, 16" x 12" 4-blade prop) is pretty quiet at normal cruising speeds, certainly better than a some of the hybrid installations with higher-speed lower-torque motors and smaller noisier props. As I mentioned elsewhere I recently found a solution with a 15kW/700rpm motor which would be even quieter, but this would need a much bigger prop which would need a deeper draft hull and consume more power especially in shallower canals -- so good for retrofit into such a hull, but possibly not the best choice for a new build, given current lack of dredging... 😞 

 

I did as much as possible to silence the generator given the space available, there's a smaller secondary silencer in series with the (semi-) hospital one and this helped a lot with exhaust noise compared to the standard single-silencer setup -- also sound insulation under the stern deck and sealing round the (steel) hatches. Probably not quite as good as Dave Jesse's solution on Perseverence, but enough that the exhaust noise is not the loudest thing from the steering position. I was more worried about vibration getting into the hull and being heard inside the boat, I know Dave had problems with this, and it was also obvious on other installations, so I stole an idea from industrial generator design and put an inertia frame (200kg of steel!) underneath the generator sitting on its own soft isolation feet, and this made a big difference.

 

I haven't measured the SPL at the steering position with and without the generator running, but it sounds quieter than any diesel at cruising rpm on any boat I've been on, and when the boat goes past you can barely hear it. Putting the generator in the bow (like Dave did) would make it quieter still for the steerer*** but has various installation issues (less good space utilisation, fuel tank position, cabling) which is why I chose to have all the "engineering" (including electrics) under the stern, there's nothing inside the boat at all, and only a 48V BT (no battery needed) in the bottom of the bow locker. As usual it's always a compromise, everything you choose has pros and cons, and different people will prefer different solutions... 😉 

 

*** but would exclude running it in the morning while having tea in bed, which is what we normally do -- reverse layout so bedroom is at the bow end.

Edited September 16 by IanD

[Rishworth_Bridge]

Power usage inevitably depends on both the setup of a boat and how it is used. One of the stupidest examples of the latter I have come across was a boater with whom I once shared the Braunston flight who, in the bottom lock, revealed that he had a parallel hybrid and was going to switch to electric drive so he could "listen to the birds" once he was out of Braunston. How much fuel had he wasted by not using what would have been a minimal amount of electric power through the locks? As to IanD's figures, they look reasonable if a bit higher than ours on Ampère, though I know that we cruise slower than he does and the cube law makes a huge difference. We also have a larger, slower prop than him, probably another plus factor. I don't have the sort of detailed records that he has but did calculate after our first few years that we were saving between 58 and 67% of the diesel we would have used for propulsion with a modern 4-pot. If this seems high consider the following cruder calculation. We usually cruise using 47A off our batteries (2.25kW) and charge at about 85A using about 1.5 litres/hour. Allowing 30% for time spent not under power (locking, etc) that equates to about 0.6 litre for each hour's cruising on a typical 1.1 locks/mile canal. And remember that that is for a boat weighing 23 tonnes and with a draft of 2'6". I usually assume 1.5 litres/hour for a modern diesel in a boat of normal draft while under power and 1 while idling, equivalent to about 1.35 litres for each hour's cruising. That suggests a saving of 56% though comparison with a diesel in a boat with our draft would almost certainly be more favourable. IanD's diesel figures are more sophisticated than mine but as slowing for moored boats is omitted in both my calculations, the difference probably isn't material. 

Our original 400W of semi-flexible solar panels failed after 3 years and were only replaced (with rigids) when the price of diesel rocketed a couple of years ago. In their first year they produced just under 300 kWh of power, saving about 90 litres of diesel. If that is maintained they will pay for themselves in just over 3 years. Larger installations, if they don't fail prematurely, will obviously contribute more.

Turning to domestic matters, electric isn't necessarily more efficient. In fact, it can sometimes be worse than using a primary energy source like gas, though there isn't much in it. We try to maximise our fuel efficiency by making good use of waste heat. After swapping our Bubble for a simpler Kabola oil stove to get rid of incompatible thermostat problems our generator cooling water now passes through  a 50 litre domestic hot water calorifier followed by a 120 litre one which runs underfloor central heating. Our horizontal calorifier isn't very efficient and we can only store enough heat for about 4 hours of meaningful heating and the floor area of our (probably any) boat isn't large enough for the heating to be sufficient on its own in cold weather. Nevertheless, it's 4 or 5 kWh that doesn't need to be found from another source. Where we missed out is heat from our Quattro which isn't as efficient as we expected, certainly while charging. If starting again I would include a small fan and a bit of ducting to capture this heat.

[Alan de Enfield]

2 minutes ago, Rishworth_Bridge said:

Our original 400W of semi-flexible solar panels failed after 3 years and were only replaced (with rigids)

 

That is my understanding of life of 'flexibles' but IanD says he has purchased 'better ones' with a 10 year guarantee, but, as far as I am aware the technology has not changed over the last few years.

I have never had flexibles (too many horror stories) but have friends who have and they all report similar problems of a 'short life'

[BoatinglifeupNorth]

Reading this, this thread is a good read for anyone considering buying an electric boat. Not because of the technical stuff but because of the usage/cost ratio. As what gets me is how little usage(cruising) @IanD has had out of the boat in relation to the financial outlay (buying the boat and yearly costs). Yes he’s a leisure boater not a livaboard and has mentioned the weather restrictions.

 Taking away the aprox 2 weeks delivery travel to his base area he’s been out cruising aprox 36 days.

 I appreciate the real life figures @IanD has given and also not saying electric boats are the “best thing since sliced bread” but if I was thinking of buying a £225K - £300K plus boat for leisure use and not livaboard and also taking into account mooring fees, licence, insurance and yearly running costs of another £5K ish. I would seriously ask if it’s a financially viable prospect, short or long term. Or would I be better off getting out on the canals with maybe a couple of hire boat holidays a year and a sunny holiday abroad in the winter?

 These are the real world questions and figures I would be asking and looking at, if I was considering buying a brand new electric boat for leisure use, taking @IanD’s one year of electric Narrowboat ownership usage as an example. Yes other people may use their boat more and then again some less.
 As of yet, the resale and price depreciation value of these high end electric boats is a bit of an unknown quantity. Speaking to a builder heavily involved in these boats, he said his experience is 4/5 years of ownership before they come onto the resale market???

Edited September 17 by BoatinglifeupNorth

[IanD]

8 hours ago, Alan de Enfield said:

 

That is my understanding of life of 'flexibles' but IanD says he has purchased 'better ones' with a 10 year guarantee, but, as far as I am aware the technology has not changed over the last few years.

I have never had flexibles (too many horror stories) but have friends who have and they all report similar problems of a 'short life'

The issue with flexible/semi-flexible panels is how they are built and mounted, because any actual bending or movement is what leads to failure, usually due to water ingress and  corrosion. The "flexible" panels are quite bendy (hence the name) and prone to this type of failure. The "semi-flexible" ones when vacuum-bonded down to a steel roof don't actually bend or move at all, the whole structure is rigid -- which is also why they can be walked on without damage. Boatbuilders who have used these for years like this have not had any failures.

[Alan de Enfield]

54 minutes ago, IanD said:

The "semi-flexible" ones when vacuum-bonded down to a steel roof don't actually bend or move at all, the whole structure is rigid -- which is also why they can be walked on without damage. Boatbuilders who have used these for years like this have not had any failures.

 

The ones that @Rishworth_Bridge was talking about were quoted as being 'semi flexibles'.

[David Mack]

2 hours ago, BoatinglifeupNorth said:

Reading this, this thread is a good read for anyone considering buying an electric boat. Not because of the technical stuff but because of the usage/cost ratio. As what gets me is how little usage(cruising) @IanD has had out of the boat in relation to the financial outlay (buying the boat and yearly costs).

That's not unique to electric boats. For most of us the depreciation and running costs probably amount to more than the cost of hiring for a week or two each year. But ownership brings the freedom to come and go when and where you want, and in a boat you have chosen, rather than a standard hireboat design.

[Rishworth_Bridge]

A few more comments. Ampère's solar panels were bonded to the roof in accordance with the manufacturer's instructions and appeared to fail by delamination - white spots which grew to patches the size of postcards. I'm sure that panels will have improved since then but am pleased, if a little surprised, to learn that IanD has got a 10 year warranty. An Internet search about 12 months ago suggested that a life of 5 years was about average, the longest I found being 8. My understanding is that heat is the principal problem. Panels are mostly black so absorb heat easily and boat roofs (if there is any left that isn't under panels) also get hot so can't dissipate much heat. What appears to be needed is a method of positive cooling. The obvious one would be a double-skinned roof through which cold water could be passed, though I hate to think what this might cost. Ortomarine are mounting panels on thin plastic sheets like that in the photo, something which will certainly allow some ventilation though I doubt that it will offer a complete solution. My current thoughts are to try passing cold water through capillary matting (as used in ceiling heating) attached to the underside of the roof. Anybody fancy trying it?

As to use, since taking ownership of Ampère at Crick in May, 2015, we have done something over 5,500 miles and almost 4,000 locks and expect to do about another 100 miles and a similar number of locks before the end of the year. Although we are registered as continuous cruisers and spend more time aboard than at home, we aren't live-aboards, putting the boat into marinas or boat clubs or occasionally leaving it pinned to the bank if we need to be elsewhere. So far this year it has spent 12 weeks in marinas or boat clubs (with another 2 due to start tomorrow) and about 3 pinned to the bank. Doing relatively little cruising for the time spent onboard means that a disproportionate amount of our fuel goes on domestic use rather than propulsion, particularly when our oil stove is running during the winter.

[IanD]

1 hour ago, Alan de Enfield said:

 

The ones that @Rishworth_Bridge was talking about were quoted as being 'semi flexibles'.

 

Yes I know, but the devil is in the details -- just which kind of panels were they, and more importantly how were they fitted and connected?

 

A "semi-flexible" panel (which type?) loosely attached to the roof (e.g. double-sided tape) and with vulnerable topside connectors is a different beast to the almost-rigid ones (maximum bend radius about 3m IIRC)  with a composite aluminium/glassfibre backing plate and robust backside connectors, vacuum-bonded directly down to the roof. This is what the hybrid boatbuilders like Finesse (and others) use, but a large part of what makes them reliable is how they're fitted, which is not something that can easily be done by inexperienced/amateur fitters as a retrofit onto an existing boat. AFAIK these panels fitted like this have shown no reliability problems over a large number of boats over several years.

 

41 minutes ago, David Mack said:

That's not unique to electric boats. For most of us the depreciation and running costs probably amount to more than the cost of hiring for a week or two each year. But ownership brings the freedom to come and go when and where you want, and in a boat you have chosen, rather than a standard hireboat design.

 

As I've said many times, having a new boat built for part-time/holiday use is a luxury which makes little or no financial sense, an expensive hybrid boat even less so -- hiring would be considerably cheaper. But then you can't hire boats like mine, certainly not one with the kind of features I wanted, and my kids who probably couldn't afford more than two grand a week to hire a boat in summer can use it "free". Being able to choose when to go away on it and change your mind at short notice (instead of booking a year ahead) is also a huge advantage.

 

And personally speaking, I'd rather have the money used for all this (and helping support UK boatbuilders and businesses) than sitting in the bank or being invested in property or wasted on an expensive bright red Italian car that spends most of its time stuck in traffic... 😉 

 

28 minutes ago, Rishworth_Bridge said:

A few more comments. Ampère's solar panels were bonded to the roof in accordance with the manufacturer's instructions and appeared to fail by delamination - white spots which grew to patches the size of postcards. I'm sure that panels will have improved since then but am pleased, if a little surprised, to learn that IanD has got a 10 year warranty. An Internet search about 12 months ago suggested that a life of 5 years was about average, the longest I found being 8. My understanding is that heat is the principal problem. Panels are mostly black so absorb heat easily and boat roofs (if there is any left that isn't under panels) also get hot so can't dissipate much heat. What appears to be needed is a method of positive cooling. The obvious one would be a double-skinned roof through which cold water could be passed, though I hate to think what this might cost. Ortomarine are mounting panels on thin plastic sheets like that in the photo, something which will certainly allow some ventilation though I doubt that it will offer a complete solution. My current thoughts are to try passing cold water through capillary matting (as used in ceiling heating) attached to the underside of the roof. Anybody fancy trying it?

As to use, since taking ownership of Ampère at Crick in May, 2015, we have done something over 5,500 miles and almost 4,000 locks and expect to do about another 100 miles and a similar number of locks before the end of the year. Although we are registered as continuous cruisers and spend more time aboard than at home, we aren't live-aboards, putting the boat into marinas or boat clubs or occasionally leaving it pinned to the bank if we need to be elsewhere. So far this year it has spent 12 weeks in marinas or boat clubs (with another 2 due to start tomorrow) and about 3 pinned to the bank. Doing relatively little cruising for the time spent onboard means that a disproportionate amount of our fuel goes on domestic use rather than propulsion, particularly when our oil stove is running during the winter.

 

That's interesting. The comments about heat are -- in my opinion! -- not really correct, if you look at how panels heat up (and are cooled). Flat panels are heated up by the sun and get pretty hot, they can only lose that heat by radiation (ineffective at these temperatures) or convection (less effective in still air) -- mounting them above the roof helps keep the roof cool but means the panels run even hotter, try touching one on a summer's day. Remember that with 1kW/m2 incoming light in summer, about 200W ends up as electricity which means 800W ends up as heat... 😞 

 

Semi-flexible panels bonded directly to a steel roof (typically 4mm thick?) can dump some of the heat into the roof which is a pretty good heat conductor, this then carries heat to the sides and down the cabin walls. It's not an especially good cooling path but it's better than dangling a flat panel in free air. But for this to happen (and not flex, see below...) you need a continuous adhesive bond line under the panels, not just a few stripes to hold it in place -- which IIRC is what some of the suppliers recommend... 😞 

 

Next time I'm on the boat on a sunny day I'll point a laser thermometer at the panels on my roof and a boat next door with flat panels and see which is hotter, and I'm confident that the flat panels will be hotter.

 

For the panels to not delaminate -- which is always a possibility! -- they need to be kept as rigid as possible, which bonding directly to the steel roof does. Putting a relatively flexible plastic panel (not even solid!) like the one pictured underneath them increases the chance of flexing/movement either over temperature or when being walked on, and I would have thought is a bad idea rather than a good one -- and it will also make the panels run hotter unless you actively blow cool air through the channels. This whole problem is quite similar to issues I deal with at work on a regular basis regarding cooling and temperature cycling of things that get hot (silicon chips) connected to rigid metal plates (heatsinks -- usually with fins...) to keep them cool, with some adhesive/thermal interface material in between, where temperature and reliability depends on understanding how all the different elements interact as they heat up and cool down -- and the answer is not always immediately obvious, and things that look like a good idea at first glance often turn out not to be.

 

If in spite of all this the panels start to delaminate in a few years like Ampere's then I'll admit I was wrong and replace them (hopefully under guarantee) -- but even if I have to pay, the cost of this will still only be a tiny fraction of the annual cost of running the boat, never mind buying it in the first place... 😉 

Edited September 17 by IanD

[cuthound]

39 minutes ago, David Mack said:

That's not unique to electric boats. For most of us the depreciation and running costs probably amount to more than the cost of hiring for a week or two each year. But ownership brings the freedom to come and go when and where you want, and in a boat you have chosen, rather than a standard hireboat design.

 

Indeed, shared ownership is the cheapest way to get a month or so on a boat every year. That is why I had shares in boats until I retired. Only then did it become financially viable for me to own whole a boat of my own.

[missingtheboat]

On 14/09/2024 at 11:23, IanD said:

I'm still pleased with the boat though, it's doing what I wanted it to

I'm glad to hear this Ian. It's generous of you to share so much information about how your boat is performing in reality. It is especially useful given that the boat has undoubtedly been very well thought through, designed and built, so perhaps represents close to optimum performance - and so this info is all the more valuable in enabling potential buyers to have realistic expectations. As you've said (many times) - you were happy to pay a premium for silent cruising, so most of the 'value for money' comments seem to me to be missing the mark. 

[IanD]

6 minutes ago, missingtheboat said:

I'm glad to hear this Ian. It's generous of you to share so much information about how your boat is performing in reality. It is especially useful given that the boat has undoubtedly been very well thought through, designed and built, so perhaps represents close to optimum performance - and so this info is all the more valuable in enabling potential buyers to have realistic expectations. As you've said (many times) - you were happy to pay a premium for silent cruising, so most of the 'value for money' comments seem to me to be missing the mark. 

 

That's exactly why I posted the results 🙂 

 

In spite of all my careful planning I'm not sure it's as close to optimum as possible just yet, there's still some way to go with the generator/charging setup but I'm confident this can be resolved. I'm an engineer so I'm not at all surprised that everything wasn't 100% perfect from the word go, with a new project like this there are always going to be some teething troubles which don't become obvious until after using it for some time.

 

It should also be pointed out -- which should be clear from the numbers -- that the advantages of such a boat are bigger if you don't do a lot of cruising hours away from your mooring, like going slowly, and mostly use it in summer, so that more of the power comes from solar. If you want to travel at diesel boat speeds for 8 hours a day every day to get one of the harder-work cruising rings done in a week, you're going to use a lot more power, and a lot of it is going to have to come from the generator running more hours per day. Still has advantages, but they're reduced. That's reality as opposed to rose-tinted "electric boat" glasses... 😉 

 

My boat is and probably always will be a luxury, which like many other things is nice if you have the money to spare; if you want value for money, either buy a much cheaper secondhand boat or do what I've done for many years and hire, depending on how much time you plan on spending onboard... 😉 

[missingtheboat]

18 minutes ago, IanD said:

In spite of all my careful planning I'm not sure it's as close to optimum as possible just yet, there's still some way to go with the generator/charging setup but I'm confident this can be resolved. I'm an engineer so I'm not at all surprised that everything wasn't 100% perfect from the word go, with a new project like this there are always going to be some teething troubles which don't become obvious until after using it for some time.

Of course, I'm sure you will be able to make improvements - but that level of skill, knowledge and tweaking ability is unlikely to be shared by all that many potential buyers of 'electric' boats - so it's reasonable to assume that the figures you present here could be close to the best that a lot of people would end up getting - or maybe even considerably better, even at this early stage. 

 

When we were doing our research before deciding on a diesel boat, we spoke to a few owners and builders and the most concerning aspect was how some boats were launched and subsequently found to have unexpected issues (e.g. more than expected diesel usage, unexpected generator behaviour). My sense was that these were mostly 'configuration' issues and sometimes improvements were made by the builder or a third party, but not always to the owners full satisfaction (which could be related to the point about unrealistic expectations on the part of either the owner or the builder).  

 

If I were an engineer myself I'd perhaps be more willing to take that stuff on - but as things stand, it feels like it's too early for me. I know I'd just have constant nagging doubts about whether everything was working as well as it could be. Still, it all makes for fascinating reading. 😊

[IanD]

Just now, missingtheboat said:

Of course, I'm sure you will be able to make improvements - but that level of skill, knowledge and tweaking ability is unlikely to be shared by all that many potential buyers of 'electric' boats - so it's reasonable to assume that the figures you present here could be close to the best that a lot of people would end up getting - or maybe even considerably better, even at this early stage. 

 

When we were doing our research before deciding on a diesel boat, we spoke to a few owners and builders and the most concerning aspect was how some boats were launched and subsequently found to have unexpected issues (e.g. more than expected diesel usage, unexpected generator behaviour). My sense was that these were mostly 'configuration' issues and sometimes improvements were made by the builder or a third party, but not always to the owners full satisfaction (which could be related to the point about unrealistic expectations on the part of either the owner or the builder).  

 

If I were an engineer myself I'd perhaps be more willing to take that stuff on - but as things stand, it feels like it's too early for me. I know I'd just have constant nagging doubts about whether everything was working as well as it could be. Still, it all makes for fascinating reading. 😊

 

The point about bug-fixing/making improvements is that this knowledge is then available for subsequent builders/boaters, especially if it's just configuration/software issues -- and yes, I've had several of these too. If you do what I did and dive into something relatively early in the rollout, you're more likely to encounter such issues -- if you want to play safe, wait until all the early adopters like me have shaken all the gremlins out before jumping in... 🙂 

 

What I'd certainly suggest before adopting *any* new technology -- for example, electric/hybrid boats -- is going with a supplier who has already built/debugged a decent number of them, has found out what does and what doesn't work (and modified what they build as a result), doesn't cut corners to try and save money, and is not going to walk away from problems. The time for cost-reduction (and possibly corner-cutting...) is after something has been established and is out there and debugged in the real world; new technology always costs more when it's introduced, and the early adopters pay for this.

[IanD]

One reason for the low solar yield is very probably because while out cruising and moored in visitor moorings where there may be little choice of spaces (so you have to take what you can get) you inevitably spend a fair amount of time in full or partial shade, as opposed to full unshaded sunlight which is what all the solar panel yield calculators use.

 

For example, in our recent trip earlier this month we averaged just under 3kWh/day in mixed weather, but in the week since we got back with the boat moored in the (unshaded) marina it's been averaging almost double that -- three days have been around 6.5kWh/day, compared to the highest days we saw in a fortnight's cruising which were around 4kWh/day.

 

So my assumption that average yield in summer would be about 7kWh/day (2.1kW of flat-mounted panels) might be true if you're moored up with no shade, but will be too optimistic if you're actually moving round the system -- certainly while cruising, but also when moored unless you're lucky with where this is.

 

Across all trips in the last year, actual solar yield per day comes out at 68% of the predicted value (3.2kWh/day vs. 4.6kWh/day) -- so as if I had only 1.4kW of panels not 2.1kW... 😞 

 

(and the gap was even bigger in summer, only 58% of predicted...)

 

P.S. Predicted yield from https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#api_5.2

Edited September 17 by IanD