Twin Electric! Salona Yachts

[geem]

Yet he (and you) didn't show any kind of workings or sources, and somehow quoted a bunch of figures completely at odds with most peoples experience and most other sources.

Thats because he is independent and not trying to sell you lithium. What motivation do you think he has to bend the truth?
When I was doing renewable energy assessments as a consultant for commercial developments nothing stacked up financially in favour of renewables but you still see commercial buildings full of solar panels. With pay back circa 20-23 years typical. The reason people do it is to improve their green credentials or because the solar panel supplier/installer is not telling the truth and they didn't take independent advice. This is reality.

 

[lustyd]

He didn't offer the truth, he offered opinions. That's the difference between showing how you arrive at a conclusion and not. Given your lack of interest in electric yachts you've spent a lot of time hijacking this thread for no good reason!

 

[geem]

He didn't offer the truth, he offered opinions. That's the difference between showing how you arrive at a conclusion and not. Given your lack of interest in electric yachts you've spent a lot of time hijacking this thread for no good reason!

Wrong again. Electric drives are very interesting. This isn't hijacking. Its debate. You seem to have a problem with people disagreeing with you. You have had evidence from Yachting Monthly. You simply choose to ignore it. You submit very simplistic figures based on a choice of lead batteries nobody in the right mind would choose. You don't factor in the cost of conversion to lithium from lead but you expect everybody to believe your figures. I won't go away. This is far too much fun?

 

[lustyd]

Actually I explained that the Lithium batteries chosen were also extremely expensive, but you've skated over that too. In reality you're looking at £400 for a 110AH LifePO4 battery right now, but that would have just brought more argument from you so I decided to stick with Victron and selected some of similar capacity. You, I note, still have not shown your workings nor a source with credible numbers comparing the two. The YM article wasn't just rejected I raised a very valid point that service life is important to include. If one technology lasts four times or more longer then you must account for that.

There is no conversion cost, this is a brand new yacht. Keep arguing if you like, your credibility diminishes with each new post as you refuse to provide any substance and continue arguing incessantly against facts and industry trends. Before long I'll add you to my ignore list as it's becoming clear you have no useful contribution to make.

 

[geem]

Actually I explained that the Lithium batteries chosen were also extremely expensive, but you've skated over that too. In reality you're looking at £400 for a 110AH LifePO4 battery right now, but that would have just brought more argument from you so I decided to stick with Victron and selected some of similar capacity. You, I note, still have not shown your workings nor a source with credible numbers comparing the two. The YM article wasn't just rejected I raised a very valid point that service life is important to include. If one technology lasts four times or more longer then you must account for that.

There is no conversion cost, this is a brand new yacht. Keep arguing if you like, your credibility diminishes with each new post as you refuse to provide any substance and continue arguing incessantly against facts and industry trends. Before long I'll add you to my ignore list as it's becoming clear you have no useful contribution to make.

A brand new yacht that costs £70k more than the diesel alternative. That really doesnt need any more comment. We are not even arguing about that boat. We had moved on to comparison of lead and lithium.
You quote £400 for a lithium battery but you don't even say who made it. That gives no idea of the quality of the cells, the warranty available or life expectancy. By comparison I can have a Trojan T105 for £150 here in the UK. Friends had a bank of these on their yacht in the tropics ( and therefore subject to high heat conditions that reduce life expectancy) but they still lasted eight years. They were a bit neglected. They didn't always get topped up when they needed it. They weren’t always fully charged but they still did eight years. There are so many ways to compare the technology and so many different ways to use it that figures can be very misleading. You could create any argument you want.
The argument for lithium is a good one. You can draw them down to 20% rather than the 50% for lead but in reality most of our cruising friends have large lead battery banks circa 900ah simply because they are liveaboard boats. Most dont discharge beyond the 80% fully charged mark so the lead isn't cycling and it lasts far longer than in the comparisons shown as to why lithium is better. I don't know a single liveaboard that discharges lead batteries to 50% each night. Most are set up with ample solar, wind turbines, diesel gensets, etc
The other issue that is never discussed in the pro lithium comparisons is the effect of temperature on lithium batteries. We generally cruise in the Tropics. Battery temperature is a constant headache. Any battery bank suffers dramatic life expectancy losses when subject to constant high temperatures wether lithium or lead. We have recently replaced our house bank with half the capacity of batteries simple because it is more cost effective in a hot climate to replace the bank after a few years than see it die prematurely due to heat ageing. In reality I expect even our 450ah lead domestic bank to last a few years since they are well ventilated for cooling, they see little discharge with no big loads, they are topped up during the day by a large solar array, they get wind charging 24/7 if we want to use it. We have hydro charging on the move and a diesel genset should all else fail. For us and many others the conversion to lithium, whilst the cost of those batteries is circa 3 times the cost of good lead, makes little sense. On my last boat cheap Numax caravan batteries lasted 7 years but that was in the UK with cool ambient conditions.
Lithium battery costs are dropping by 7% per annum so maybe by the next time a need a new domestic bank the price might be favourable ?

 

[lustyd]

The price is favourable now, that's what we've all been trying to get through to you I'm not going to tell you what I'd get for £400, although I did later realise that was in USD so it's actually cheaper than that. Suffice to say they are a respected brand of Lithium cells and you would not accept any answer regardless, so do your own research and come to your own conclusions as I have no motivation to satisfy your perverse need for an argument. If it makes you feel slightly better, you have won, the electric boat thread has dies at your hands and you've sucked all of the enthusiasm out of it and the people discussing it. Well done.

 

[geem]

The price is favourable now, that's what we've all been trying to get through to you I'm not going to tell you what I'd get for £400, although I did later realise that was in USD so it's actually cheaper than that. Suffice to say they are a respected brand of Lithium cells and you would not accept any answer regardless, so do your own research and come to your own conclusions as I have no motivation to satisfy your perverse need for an argument. If it makes you feel slightly better, you have won, the electric boat thread has dies at your hands and you've sucked all of the enthusiasm out of it and the people discussing it. Well done.

I think you will find it died its own death?

 

[Rappey]

6 pages of the pros and cons debated from all angles.
Overall pretty interesting .
Just like anchor videos both sides can be argued for and against.

 

[nestawayboats]

As we are on the YM Forum, let’s use some figures from an excellent and recent Yachting Monthly article - cost per usable Ah (ie after allowing for deeper discharge capability of Lithium)
- Flooded Lead Acid - £2.68 / Ah u
- AGM - £3.13 - £7.50 / Ah u
- Lithium Ion - £9.00 - £16.49 / Ah u

So Lithium still much more expensive per usable Ah - and probably need to change quite a bit of electrical management systems to get best use of them.
But if doing new build or major upgrade to whole system, and prepared to put money in up front for hopefully longer lifespan, then can start to make long term sense over 10 years or so.

I don't know who came up with these figures, they look high to me (for lithium, today). An Epropulsion E-Series E175 battery retails at £3800. The 175 bit refers to 175Ah at 48V. I assume the Ah being referred to above are at 12V - if I'm wrong I apologise.

But if my assumption that we're talking about "12V amp hours" is correct then 175Ah at 48V is the same as 700Ah at 12V. (It would be easier if we went for Wh - ie Amp hours times Voltage - as a lowest common denominator but I'll stick with it.)

£3800 divided by 700 is £5.42 per Ah (at 12V).

If we say you can only use 80% to ensure maximum longevity of the lithium batteries then the calculation is £3800 divided by 560 (being 700 x 0.8) which gives us £6.79 per Ah (at 12V).

Directly comparable with high end AGM then, on these numbers. But the lithium ones should last many more charge/discharge cycles, so total lifetime cost will actually be less (unless that was already in the YM figures, I don't know). The E-Series batteries are rated at 3000 cycles to 80% capacity, ie charge and discharge them every day for 8 years (8x365 = 2920) and they'll still have 80% of their original capacity. I don't think any lead acid or AGM batteries claim anywhere near that.

Also, the lithium ones will be somewhere around one quarter to one third of the weight/volume. They can be charged much faster, and run much higher loads (such as propulsion!), with less detriment to their life. In comparing "cost per usable Ah" like this no value is being applied to the advantages of lithium.

Ian, Nestaway Boats Ltd

 

[nestawayboats]

It's probably about time for me to "come out". I took the plunge last year and made my Sadler 29 fully electric. Apologies if I have missed somebody while skim reading, but I think I'm the first contributor to this thread who actually has an electric yacht.

I was planning to do it this Winter anyway, then my Bukh DV20 kept overheating in August and I got p*ssed off with it. I just didn't want to spend any time fixing a diesel engine that I didn't want anyway. So we hauled her out, pulled out the Bukh, ground out the shaft tube, glassed in a load of reinforcement, and bolted a 10kW prototype Epropulsion pod motor on the bottom. We put 18kWh of 48V lithium (equivalent to 1500Ah at 12V if you prefer) where the Bukh used to be which was actually a net weight loss (Bukhs are really heavy!). 2x Epropulsion E175 batteries is an amazingly good fit where a DV20 used to be. We also took the 70 litre diesel tank out of the cockpit locker, which made the cockpit locker usefully bigger. Overall this installation is approx 100kg lighter than what was there before, slightly lower and more central in the boat.

The range/speed figures of this installation on pure battery are as follows:
- at 1kW output we achieve approx 3.3 knots which would give us about 54nm if we run batteries flat. 43nm if you say 80% maximum depth of discharge, although you can use the last 20% if you have to, and it won't kill the batteries, just don't do it all the time.
- at 2kW we get 4.5 knots, 40nm
- at 3kW 5 knots, 30nm

Above 3kW the returns diminish very fast, 6kW gives us 6 knots but only 18nm. Applying the last 4kW (ie up to full 10kW) is pointless, just pull a bigger wake.

40nm at 4 knots is plenty for what we do, we could put more batteries in but I don't think I will. I guess with an economical cruising speed of 4 knots I think a little bit more about which way the tide is going, but from what I remember from doing they RYA courses that would be classed as good seamanship...

Our 10kW pod - as mentioned a prototype from Epropulsion - also has regen. We recharge the batteries when sailing. Pottering around the Solent, if we have wind, we usually find the total net usage of electricity over a weekend is very little. The batteries won't be absolutely full on Sunday night, but I was frequently not bothering to recharge them for 2 or 3 weekends in a row. Unfortunately I can't be more accurate than this on the regen numbers as the software hadn't been written in time! Sailing at 4 to 5 knots I think the regen costs us about half a knot, but if there's half a decent breeze the Sadler does 5.5 to 6 knots anyway (hull speed), and then I don't think would go much faster without the drag.

As an aside we're also changing from the 10kW prototype pod to a 6kW production pod (officially announced today!). Last season we didn't once use more than 6kW, other than to find out that the last 4kW was pointless. A 6kW pod is smaller (less drag) and lighter. Also the 10kW pod is 96V whereas the 6kW pod is 48V, just easier to deal with.

The other work before we relaunch this year will be to pull out the 400Ah of lead acid batteries (inherited when I bought the boat!) and run the 12V side off a DCDC converter (48 to 12V). There's just no sense in keeping that 100kg of lead acid batteries there. If I wanted to I could then use that space for an extra 9kWh lithium battery. And where the fuel tank used to be, some of that space could be used for yet another 9kWh battery.

With 36kWh battery capacity then I could have an 80nm all-electric range at 4 knots on a Sadler 29, slightly lighter than the old diesel installation and with a slight gain in space.

However if I wanted more range more cheaply I could take a 2kW generator. I might even do so, if crossing the Channel for example. The most likely scenario for running out of juice is a flat calm, when it should be reasonably safe to run the generator.

That is just numbers. I am not allocating any value to how lovely it is to use. Quiet, smooth (smooth, you find out, is nearly as significant as quiet), no diesel fumes in the cockpit in the downwind drift home nursing a hangover on Sunday morning. Complete control of prop speed, you can apply 50W if that's what you need to get into a berth, no putting in and out of gear at diesel idle speed.

Oh, the cost of all this? 18kWh of battery plus a 6kW pod is £10k. Yes it's more than replacing the diesel would have been, but not that much more if you were also going to replace the diesel tank, exhaust system, shaft, propeller, etc (everything is new in the electric system).

Ian, Nestaway Boats Ltd

 

[lustyd]

Thanks Ian, really great to hear about a real world example. Presumably a larger boat would increase speeds without using significantly more power as your main problem sounds like overcoming hull speed?

 

[NormanB]

Very interesting post, thank you for sharing. Would be good to see some pics. What do you think about the potential advantages of getting rid of propane and going induction and upgunning the lithium to provide the ‘headroom’?

 

[lustyd]

The chap from the green yachts place in the video has a post about induction and suggests that while fine on larger boats it's a bit too hungry for smaller boats to sensibly achieve. I don't think going electric on the cooking gives such big advantages as on propulsion though so not too big a deal to keep the gas

 

[NormanB]

Thanks Ian, really great to hear about a real world example. Presumably a larger boat would increase speeds without using significantly more power as your main problem sounds like overcoming hull speed?

Not so sure about that. Larger ( longer waterline) boats have a higher max theoretical hull speed but their powering requirements are still higher at any given speed than a shorter vessel Hull resistance is higher, bow wave making probably too similar to worry about.

 

[nestawayboats]

The Sadler 29 is quite an easily-driven hull but yes we're up against the 24ft waterline or whatever it is (I haven't checked). Longer yachts with longer waterlines will similarly be very easily-driven up to half hull speed or so (eg 1kw for 3.3 knots for the Sadler), but it will still need more power than the shorter (lighter) boat. Unless you go to much higher length to beam ratios or length to displacement ratios, when the hull speed rules of thumb start to break down.

 

[lustyd]

Not so sure about that. Larger ( longer waterline) boats have a higher max theoretical hull speed but their powering requirements are still higher at any given speed than a shorter vessel Hull resistance is higher, bow wave making probably too similar to worry about.

The point being that propelling a boat requires a power relative to weight and resistance - this is low. Going faster you need to overcome the bow wave - this is extremely high by comparison. The difference in fuel consumption between a 30' and a 40' yacht is not that great at cruising speeds generally. Ians example shows that up to a point there are useful gains for a little more power, but the point where it's a problem is about what his boat would be happy with and then suddenly not much extra speed per watt. My assumption was that for a comparable energy a 36' would therefore "hit the wall" a bit later and go faster

 

[NormanB]

The point being that propelling a boat requires a power relative to weight and resistance - this is low. Going faster you need to overcome the bow wave - this is extremely high by comparison. The difference in fuel consumption between a 30' and a 40' yacht is not that great at cruising speeds generally. Ians example shows that up to a point there are useful gains for a little more power, but the point where it's a problem is about what his boat would be happy with and then suddenly not much extra speed per watt. My assumption was that for a comparable energy a 36' would therefore "hit the wall" a bit later and go faster

Although we are in danger of ‘dancing on the head of a pin’, all my training and experience in hydrodynamics and displacement hull power requirements tells me: that all other things being equal and with vessels of similar hull form, then a shorter vessel will require less power all the way from moving away from rest to achieving max hull speed than a longer vessel.The difference in the 2 cube law graphs will be small up to about 3 knots and increasingly significant afterwards - well that’s the cube law for you.??

 

[lustyd]

Sorry Norman, I wasn't saying it would use the same power at all, perhaps I worded it badly. What I was saying was that the larger yacht would achieve a better speed before the power ramp up occurs. The speeds Ian posted were low for normal cruisers, but it's not a terribly long boat. As such I'd expect a 36' boat to manage 6kt before the serious diminishing returns started. Obviously it would need more power to do so, but the overall list would look similar just with higher numbers, if that makes sense. I'd assume a bigger battery on a bigger boat too, so using completely made up numbers something like:
- 1.5 kW output we achieve approx 4 knots
- at 2.5kW we get 5knots
- at 3.5kW 6 knots
then 6.5 kt becomes difficult and 7 pointlessly wastes energy. As I said I made up the numbers to show what I meant about bigger yachts making better speeds.

 

[NormanB]

Sorry Norman, I wasn't saying it would use the same power at all, perhaps I worded it badly. What I was saying was that the larger yacht would achieve a better speed before the power ramp up occurs. The speeds Ian posted were low for normal cruisers, but it's not a terribly long boat. As such I'd expect a 36' boat to manage 6kt before the serious diminishing returns started. Obviously it would need more power to do so, but the overall list would look similar just with higher numbers, if that makes sense. I'd assume a bigger battery on a bigger boat too, so using completely made up numbers something like:
- 1.5 kW output we achieve approx 4 knots
- at 2.5kW we get 5knots
- at 3.5kW 6 knots
then 6.5 kt becomes difficult and 7 pointlessly wastes energy. As I said I made up the numbers to show what I meant about bigger yachts making better speeds.

Yeah OK.
The power clue is to look at an AWB catalogue/brochure and compare the installed power for a 30 footer, 33 footer, and 40 footer et seq.?

 

[lustyd]

ok so you seem to be ignoring the point. I'll give up