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Old 20-12-2015, 14:59   #166
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Re: Tug of War - Electric vs Diesel

Quote:
Originally Posted by BigBeakie View Post
Jim,

To take your questions one by one:
1. The genset for battery charging does consume diesel. It is required only when the range of the propulsion LFP bank is exceeded. How often that happens depends mainly on where you cruise as you well know, as well as how well your boat sails in light winds ie whether you have an efficient performance cat or a condomaran. If it is not used very often, then the genset can be considered like an insurance policy, hardly ever needed but good to have if circumstances arise.
However the Island Cruising Association out of NZ has surveyed their members ( over a long period of time) and found a surprisingly ( to me anyway) high number of engine hours per year reported by their members that actively cruise the South Pacific. They report an average of 700 engine hours/year. Say average diesel burns 4 liters /hour and at $2/liter thats $5,600 per year fuel.
Obviously this is not the cruising profile of either Rustic Charm or 44' Cruising Cat, so diesel hybrid electric is not a cost justifiable solution for them. It sounds to me Rustic Charm has very modest motoring requirements, so maybe EP could work for him where he can plug in at the end of the day.

But as I reported, one electric cat uses 1 liter /hour to recharge enough to keep going non-stop at cruising speed. Smaller electric motors, smaller generator required, system in balance. To ask one of your rhetorical type questions, is 1 liter per hour less than 4 liters per hour? Which system is more efficient?

2. But EP does not rely ALONE on the genset. For the vast majority of the time EP is used, it uses free fuel. So which is more efficient, a system that you pay at the pump every single time you fill up, or one where the fuel dock attendant says "Never mind, it's on the house?"

3. No, over 5 years the LFP bank would not need to be replaced. An LA system undoubtedly would , due to the lower capacity of charge cycle life.

4. Users of these EP systems that use feathering props for regen report a loss of a quarter to half a knot boat speed during regen. I'll take that hit any day of the week for the amount of charge that is achieved back into the LFP bank. Don't forget, when the charge is topped up, then you pop the props back into feathering mode. So you've been on the hook in some nice lagoon for a week and it's been really cloudy so not enough solar to keep house bank up, just go sailing for a few hours under regen and you just got a free fill,.... again.

Sounds pretty efficient to me. And do it again and again over a 5 to 10 year cruising plan.
BB, to take your replies one by one:


1.With all due respect for the ICA, few of the participants are really full time cruisers. They are more holiday or sabbatical cruisers, out for a guided tour of some destination with all the rough edges smoothed off by the organizers. Nothing wrong with this, but to use their engine hour numbers as representative of all cruisers is faulty. We encounter these folks frequently and are reasonably familiar with their sailing habits. They are on a schedule (loose, but still a sched) and that tends to increase engine usage a lot.

And for what it is worth, we have been full time cruising for a long time now, and our engine usage is a lot less than what you report. I don't have the numbers for Insatiable One at hand, but for I-2, well, we have owned her for almost 13 years now and have put 3800 hours on the engine which works out to be around 290 hours per year. During that time we have logged just over 51,000 miles. Our engine consumes ~2.5 litres/hour at 6 knots in moderate sea conditions, not four, and we have never yet paid 2 bucks a liter for diesel, so your ICE cost numbers seem pretty inflated to me.

Finally, the 1 liter/hour usage report is pretty impressive. I'd like to suggest, however, that if that boat had a similarly sized ICE direct drive, it would use less. The loss of efficiency for the mech/electrical/mech conversion losses just can't be ignored (at least by me).

2. Free fuel? Yes, the solar input is incrementally free, and if one has a large enough solar array and small enough motor usage, that is cool. But you often mention plugging in at the dock to recoup the days usage, and that ain't free. Perhaps some marinas don't charge you for electricity, but most do these days, and even if you are not charged directly, someone is paying the electrical bill and that cost is reflected in marina fees.

3.You seem quite sure that in real usage a LFP battery would not require renewal after 5 years full time cruising usage. Have there actually been enough such usage histories to establish this belief? It may be that a five year life of daily discharge/recharge is realistic, but I haven't seen much data to support the claim. Extrapolating from manufacturers cycle claims is a risky path IMO!

4. I simply do not believe that extracting enough energy from regenerating props will only slow a boat by 1/4 to 1/2 knot. When one considers that going from a fixed prop spinning with no load to a folding prop will give an increase in speed that is larger than that, it is hard to believe that extracting several horsepower (what it takes to run a decent sized charger) won't slow you down even more. The one case where your claim might be true is in situations where the boat is at hull speed, with more than enough wind power to keep it at or near hull speed despite the energy demands of regeneration. In that one case, regeneration is "free". It does not describe going out for a sail for a few hours to recharge a huge battery bank as you suggest.

Again, from personal experience, we used to have a trolling generator on Insatiable One. It put out about 10 amps at 6 knots, a trivial amount compared to the demands of your putative regenerator. That small device slowed that 36 foot mono by approximately 1/2 knot in the 4 to 6 knot speed range where it was effective.

BB, I'm not against electric propulsion. In some instances it is already viable, and it is only going to get better. But for the full time cruiser, the ones that don't live in marinas and who sometimes need to motor for longer times and distances, I remain pretty skeptical. The realistic numbers don't seem to work out.

Cheers,

Jim
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Old 20-12-2015, 17:49   #167
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Re: Tug of War - Electric vs Diesel

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Originally Posted by Jim Cate View Post
BB, to take your replies one by one:


1.With all due respect for the ICA, few of the participants are really full time cruisers. They are more holiday or sabbatical cruisers, out for a guided tour of some destination with all the rough edges smoothed off by the organizers. Nothing wrong with this, but to use their engine hour numbers as representative of all cruisers is faulty. We encounter these folks frequently and are reasonably familiar with their sailing habits. They are on a schedule (loose, but still a sched) and that tends to increase engine usage a lot.

And for what it is worth, we have been full time cruising for a long time now, and our engine usage is a lot less than what you report. I don't have the numbers for Insatiable One at hand, but for I-2, well, we have owned her for almost 13 years now and have put 3800 hours on the engine which works out to be around 290 hours per year. During that time we have logged just over 51,000 miles. Our engine consumes ~2.5 litres/hour at 6 knots in moderate sea conditions, not four, and we have never yet paid 2 bucks a liter for diesel, so your ICE cost numbers seem pretty inflated to me.

Finally, the 1 liter/hour usage report is pretty impressive. I'd like to suggest, however, that if that boat had a similarly sized ICE direct drive, it would use less. The loss of efficiency for the mech/electrical/mech conversion losses just can't be ignored (at least by me).

2. Free fuel? Yes, the solar input is incrementally free, and if one has a large enough solar array and small enough motor usage, that is cool. But you often mention plugging in at the dock to recoup the days usage, and that ain't free. Perhaps some marinas don't charge you for electricity, but most do these days, and even if you are not charged directly, someone is paying the electrical bill and that cost is reflected in marina fees.

3.You seem quite sure that in real usage a LFP battery would not require renewal after 5 years full time cruising usage. Have there actually been enough such usage histories to establish this belief? It may be that a five year life of daily discharge/recharge is realistic, but I haven't seen much data to support the claim. Extrapolating from manufacturers cycle claims is a risky path IMO!

4. I simply do not believe that extracting enough energy from regenerating props will only slow a boat by 1/4 to 1/2 knot. When one considers that going from a fixed prop spinning with no load to a folding prop will give an increase in speed that is larger than that, it is hard to believe that extracting several horsepower (what it takes to run a decent sized charger) won't slow you down even more. The one case where your claim might be true is in situations where the boat is at hull speed, with more than enough wind power to keep it at or near hull speed despite the energy demands of regeneration. In that one case, regeneration is "free". It does not describe going out for a sail for a few hours to recharge a huge battery bank as you suggest.

Again, from personal experience, we used to have a trolling generator on Insatiable One. It put out about 10 amps at 6 knots, a trivial amount compared to the demands of your putative regenerator. That small device slowed that 36 foot mono by approximately 1/2 knot in the 4 to 6 knot speed range where it was effective.

BB, I'm not against electric propulsion. In some instances it is already viable, and it is only going to get better. But for the full time cruiser, the ones that don't live in marinas and who sometimes need to motor for longer times and distances, I remain pretty skeptical. The realistic numbers don't seem to work out.

Cheers,

Jim
Hi Jim,

Well that is good feedback about your fuel use over the years and is certainly welcome as I have tried to get meaningful data from as many sources as I can. The ICA figures include their members (about 1,500) annual useage, not just when they are on the rallys. It includes running engines for some battery charging , as well as motoring. Can you point me to better data than this for full time cruisers?
We will be perhaps motoring more than most as we hope to be spending time diving in the equatorial tropics where winds can be light for long periods, and also doing some trolling for sportfishing. This admittedly may not be similar to those who go to a nice spot, stay for a month at anchor, and repeat.

Diesel prices around the world, 14-Dec-2015 | GlobalPetrolPrices.com

Here is a list of diesel prices by country and it is quite low at the moment as the Saudi's try and put the US shale oil companies out of business. So, what would you say will be the average price of diesel over the next 10 years?

Yes there is data on LFP cycle testing and depending on DOD it looks to be somewhere between 2,000 cycles at 80% DOD minimum to 8,000 cycles maximum at 50% DOD. For example, Johnson Controls guarantee their battery for 9 years to 80% DOD. But, yes, time will tell the tale.

I spoke to OceanVolt who have tested this and is confirmed with data coming in recently,,and also Kiwiprop who tested the regeneration and they got the same result. I have not confirmed any of this personally. What is your guesstimate on how much a 45' cat sailing 9 knots would slow down then?
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Old 20-12-2015, 19:13   #168
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Re: Tug of War - Electric vs Diesel

Quote:
Originally Posted by BigBeakie View Post
Hi Jim,

Well that is good feedback about your fuel use over the years and is certainly welcome as I have tried to get meaningful data from as many sources as I can. The ICA figures include their members (about 1,500) annual useage, not just when they are on the rallys. It includes running engines for some battery charging , as well as motoring. Can you point me to better data than this for full time cruisers?
------
No, I have no data source beyond my own and a few personal cruising friends experience. But that 700 hour/year number seems awfully high for an average. Consider that this means about two hours engine use every day of the year... for the AVERAGE member. This in turn means that there must be a lot of the ICA gang that run their motors significantly more than two hrs/day. Perhaps if one has engine driven freezers and bad insulation,or runs a big plasma screen display a lot... but average?? I think of our usage as being kinda high these days at ~3/4 hour per day average. We're getting older and lazier and use the engine more than we used to!

-----
We will be perhaps motoring more than most as we hope to be spending time diving in the equatorial tropics where winds can be light for long periods, and also doing some trolling for sportfishing. This admittedly may not be similar to those who go to a nice spot, stay for a month at anchor, and repeat.

Diesel prices around the world, 14-Dec-2015 | GlobalPetrolPrices.com

Here is a list of diesel prices by country and it is quite low at the moment as the Saudi's try and put the US shale oil companies out of business. So, what would you say will be the average price of diesel over the next 10 years?

--------
Beats me! If I knew I might be buying futures... In return, what do you think the price for Lithium will be as the demand goes up? I seem to have read something about escalation there.
----------

Yes there is data on LFP cycle testing and depending on DOD it looks to be somewhere between 2,000 cycles at 80% DOD minimum to 8,000 cycles maximum at 50% DOD. For example, Johnson Controls guarantee their battery for 9 years to 80% DOD. But, yes, time will tell the tale.

------
Those are impressive numbers, and I hope they are realistic, for that bodes well for the future. If they prove true in the rough and tumble world of cruising, then you are right: a five year life is reasonably attainable, and perhaps then some. Good stuff!
--------

I spoke to OceanVolt who have tested this and is confirmed with data coming in recently,,and also Kiwiprop who tested the regeneration and they got the same result. I have not confirmed any of this personally. What is your guesstimate on how much a 45' cat sailing 9 knots would slow down then?
I'm not sure what results from Kiwiprop you are referring to in the above. I'm not an experienced cat person, and have no opinion on your example. But I do know that extracting enough power from the props to run a very big charger (needed to provide useful replenishment of a big battery bank) must slow the boat down. And obviously, the amount of slowing will vary between boats and with conditions, and on the design and placement of the props. I remain convinced that that number will be more than 1/4 to 1/2 knots in most cases.

Here's a simple-minded way to visualize it: Our boat takes something like 15 HP to drive it at 6 knots. For every hour of motoring (if we were electrically driven) we would need to replace that energy. Assuming 100 % efficiency (which surely does not exist) we would have to extract 15 hp-hours of energy from the prop in regenerate mode in order to recharge the battery. If one would like to do the regeneration in a timely fashion... say twice the motoring time... it would be removing 7 1/2 HP from that available to drive the boat. With the exception of the hull speed plus example I gave earlier, this must slow the boat, and I believe significantly. Consider the example I gave of our trolling generator: 12 V, 10 A, 120 watts or about 1/6 HP, and it slowed us by about a half knot. I'm sure that my home brew setup wasn't optimally efficient, but must believe that extracting some 50 times more power will slow a boat more than my setup did.

One can, of course, elect to accept such performance hits. I might even myself, but to call it "free" is misleading IMO.

Cheers,

Jim
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Old 20-12-2015, 21:08   #169
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Re: Tug of War - Electric vs Diesel

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But as I reported, one electric cat uses 1 liter /hour to recharge enough to keep going non-stop at cruising speed. Smaller electric motors, smaller generator required, system in balance. To ask one of your rhetorical type questions, is 1 liter per hour less than 4 liters per hour? Which system is more efficient?
And as I already reported, that boat could achieve very similar speeds/fuel consumption figures running a Yamaha 9.9 HT outboard.

At a fraction of the cost.

With far greater reliability. (Yam gearboxes don't break when you run over a jellyfish.)

And with substantially more power in reserve if needed.

So yeah, which system is more COST efficient?


BTW, where did you come up with your 4 litres/hour figure?
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Old 21-12-2015, 01:49   #170
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Re: Tug of War - Electric vs Diesel

Mega culpa on the 40hp diesel consumption at 4 L/hr, I meant to say 2 L/hr which is close to what many report at cruising speed.


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Old 21-12-2015, 12:07   #171
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Re: Tug of War - Electric vs Diesel

Maybe, but not on the design of boat you keep referencing. As you know, that's a light, and easily driven boat.


There are in fact a couple of 44C's with ~ 20 hp diesels. Both report around 1 - 1.5 litre/hour at 5-6 knots on one engine.


And you're comparing a 40 hp diesel to a 6 kva generator?


Skewing the numbers to suit your agenda much? There's no way the sustainable thrust would be even remotely comparable.


How about comparing apples to apples? There are a couple of 44C's with diesels. A few with outboards. And now only one left with diesel electrics.


The diesel boats manage around 6 knots at less than 1.5 litres/hour. The 20 and 25 hp outboard powered ones would use a little more. They can all motor at speeds in excess of 9 knots if required, and can motor at 8 knots all day long.


The diesel electric can't. It's maximum sustainable speed is what? 5.5 knots? 7 knots for a brief, battery flattening burst? (And lookout for jellyfish!)


So if you're going to make a valid comparison, the electric version needs bigger motors and a much bigger genset. Even with the barely adequate system it has, it's far more expensive, and not much more economical.
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Old 21-12-2015, 14:15   #172
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Re: Tug of War - Electric vs Diesel

Interesting conversation, and I don't have a dog in this fight, so I'm approaching it as an outside observer. I went to Elkos site, and configured their setup to replace the drivetrain and aux generator in my someday (hopefully) boat, an Amel SM2000. 150 gallon fuel tank, which is above what it recommended for the 100 hp setup I priced out, so that is good to go. Tossed it all in a spreadsheet, and here's what I came up with.

EP-10000: $22,570.00 (USD)
E-Gauge VII (Upgrade Price) $594.00 (USD)
Motor Mounts Set of four (4) $240.00 (USD)


Batteries, take your pick:

EP-10000 (12) Deka East Penn AGM 4A4D, 12 volt 4-D (198 Ah) $5,400.00 (USD)
EP-10000 (12)) Deka East Penn AGM 8A8D, 12 volt 8-D (245 Ah)$6,180.00 (USD)
EP-10000 (12) Lifeline AGM GPL-4DL, 12 volt 4-D (210 Ah) $6,000.00 (USD)
EP-10000 (12) Lifeline AGM GPL-8DL, 12 volt 8-D (255 Ah) $7,200.00 (USD)
EP-10000 (12) Valence U27-12XP Lithium Magnesium Phosphate $18,708.00 (USD)
Valence Controller Interface $1,266.00 (USD)
Victron AGM, 12 volt Telecom (200 Ah) $5,400.00 (USD)

EP-10000 Hybrid Charger Elcon PFC 8000 (2) @ $4,765.00 (USD)


And finally, for the part that allows me to go more than 35 miles at a shot...

Generators for Hybrid Electric Systems
EP-10000 Hybrid Generator (30kW) Northern Lights M944W3 $28,795.00 (USD)
EP-10000 Hybrid Generator (25kW) Northern Lights M864W3 $27,465.00 (USD)
EP-10000 Hybrid Generator (20kW) Northern Lights M844LW3 $23,295.00 (USD)

Now, if I am going to lay out this kind of bread, I am going to go pretty much all out, esp on the generator. A few thousand in savings at this point is pretty meaningless, and I want all the options they make for it as well, to monitor things, and to be able to charge with shore power. The only thing I really would be up in the air about is the batteries. They go from 5k to 18k, and I'm sure the 18k ones are fabulous, but man, from over double to over triple the price of the other ones? Dunno. So, here it is finalized, it would cost me between, as best as I can calculate, between $62,895 and $80,437 if I didn't miss anything. And this is just for parts alone, not including whatever extra little bits and pieces that make everything play together nicely. And not including any labor...

Sadly, as my name isn't Gates, and the lottery deal isn't much of a sure thing, I'm probably going to have to stick with my stinky diesel engine that it came with from the factory. No doubt the cool factor is high on this setup, but affordable, it is not, at least for this guy. I know boats are expensive to maintain, but I can't imagine a person spending even half that much to replace both the genset and the motor with brand new (not rebuilt) pieces, and probably have some change left over from that to buy a few thousand gallons of diesel?


*edit*

And could someone please explain the comments about gearboxes breaking after hitting jellyfish? Can't seem to wrap my mind around that one...
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Old 21-12-2015, 20:19   #173
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Re: Tug of War - Electric vs Diesel

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And could someone please explain the comments about gearboxes breaking after hitting jellyfish? Can't seem to wrap my mind around that one...
The boat BB keeps referring to as a fine example of the viability of electric power is powered by Torqueedo electric outboards. Last time we saw this boat, one of the motors was away for repairs after the gearbox broke from hitting jellyfish.
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Old 21-12-2015, 21:25   #174
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Re: Tug of War - Electric vs Diesel

Wow. Just... wow.
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Old 22-12-2015, 00:01   #175
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Re: Tug of War - Electric vs Diesel

Did about 750nm over the last 7.5 days - time constrained delivery of a 45ft mono with adverse winds and currents so we needed to motorsail almost non stop.

We went through about 600l of diesel in a 50HP Perkins in total.

Had a couple of straits to get through with strong currents and had to run at about 80% MaxRPM for several hours at a time through them.

Do that with EP!
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Old 28-12-2015, 02:24   #176
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Re: Tug of War - Electric vs Diesel

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This brings up an interesting question. How much electric power (in kW or HP) does it take to replace a diesel without giving up any performance or capabilities?

First, the diesel loses several HP in driving water pumps, alternators, friction in the longer drive train, etc. Depending on whose data you use, size of the alternator and other variables could be typically 4-5 HP, certainly less that 10 except for unusual installations (engine mounted fridge compressor for example).

Then there is the big variable of the difference in the HP/torque curve of electric vs diesel where there seems to be no consensus at all.

Opinions I have read for electric to match diesel performance range from 40% of the diesel's rated power to about 75%.

In my case I have an engine rated at 58 HP and do not consider my boat overpowered I would shoot for the high end of the estimates so go for electric of 40-45 HP (30-35 kW) if I went electric.
Assuming the engine is rated in shaft HP, the only difference would be if you added after market items (oversize alternator, mechanical fridge, etc...). The water pump, standard alternator, etc..., are already accounted for. If you are talking about a diesel/electric system, you are probably need a larger diesel due to the power conversion losses.

As stated before the design criteria that controls HP for a cruising displacement boat is cruising at hull speed against a strong headwind or current. Assuming a properly designed system, that's peak HP for either the electric or diesel motor. HP is HP.

If off the line 0-6kts times or tug-o-war was really important, you would see diesel boats fitted with a reduction gear and a larger prop so they could achieve the same effect as the electric motor off the line.

If you drop your 40hp diesel to a 20hp electric, you could achieve the same effect by dropping to a 20hp diesel.

One interesting item:
- Where electric is most practical is for just getting in and out of harbor before hoisting the sails. I sometimes hear purists bragging about only using 5-10gal of diesel per year...of course if you are only using 5-10 gal per year, there isn't much to gain from efficiency.
- For a more typical cruiser (non-sailing purist), who doesn't hesitate to crank up the engine, they aren't going to be satisfied with an underpowered boat with limited range.
- That doesn't leave much of a market for electric drivetrains.
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Old 28-12-2015, 03:40   #177
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Re: Tug of War - Electric vs Diesel

Big Beakie. if a boat needs 35kw to drive it along, you could probably say that it's going to need that energy whether the engine is diesel or electric. A 5kw generator generates 5kw for every hour of operation and will need to operate for 7 hours to generate the 35kw of energy consumed in one hour of boat operation.

Let's imagine you wanted to motor 30 miles down the coast to the next marina. This will probably take about 6 hours and will consume 245kw of energy. Your 5kw generator will have to operate for 49 hours to recharge the batteries. Let's assume that the gennie was operating while you were motoring, you will have to sit in the marina for 43 hours waiting for the batteries to charge. Did I mention that you need to store 215 kwh of energy which will require 150 x 12v x 200 a/h lead acid batteries assuming 60% residual in order to motor that 30 miles assuming that you're operating the gennie on the way.

Just accept that 1kwh of energy consumed require 1kwh of recharge. It's that simple.

BTW, my 5kw solar system on my house covers 20 square metres which is about half the surface area of my boat. Given that I need to generate 35kw of electricity every hour to replace the 35kw I consume, I'll need a solar array 3.5 times larger than the surface area of my boat. Now that would be an interesting experience if the wind picked up and I got to sail closehauled in 20 knots of wind and 1.5 metres of waves.
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Old 28-12-2015, 04:15   #178
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Re: Tug of War - Electric vs Diesel

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I'll need a solar array 3.5 times larger than the surface area of my boat.
A bit like this then:-

http://blog.boats.com/files/8-Solar-Boat.jpg

By the way, it does not go to windward well at all.
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Old 28-12-2015, 04:20   #179
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Re: Tug of War - Electric vs Diesel

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...
- Where electric is most practical is for just getting in and out of harbor before hoisting the sails. I sometimes hear purists bragging about only using 5-10gal of diesel per year...of course if you are only using 5-10 gal per year, there isn't much to gain from efficiency.
- For a more typical cruiser (non-sailing purist), who doesn't hesitate to crank up the engine, they aren't going to be satisfied with an underpowered boat with limited range.
- That doesn't leave much of a market for electric drivetrains.
Wot 'e said!
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Old 28-12-2015, 04:31   #180
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Re: Tug of War - Electric vs Diesel

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Big Beakie. if a boat needs 35kw to drive it along, you could probably say that it's going to need that energy whether the engine is diesel or electric. A 5kw generator generates 5kw for every hour of operation and will need to operate for 7 hours to generate the 35kw hours of energy consumed in one hour of boat operation.

Let's imagine you wanted to motor 30 miles down the coast to the next marina. This will probably take about 6 hours and will consume 245kw hours of energy. Your 5kw generator will have to operate for 49 hours to recharge the batteries. Let's assume that the gennie was operating while you were motoring, you will have to sit in the marina for 43 hours waiting for the batteries to charge. Did I mention that you need to store 215 kwh of energy which will require 150 x 12v x 200 a/h Ah lead acid batteries assuming 60% residual in order to motor that 30 miles assuming that you're operating the gennie on the way.

Just accept that 1kwh of energy consumed require 1kwh of recharge. It's that simple.

BTW, my 5kw solar system on my house covers 20 square metres which is about half the surface area of my boat. Given that I need to generate 35kw hours of electricity every hour to replace the 35kw hours I consume, I'll need a solar array 3.5 times larger than the surface area of my boat. Now that would be an interesting experience if the wind picked up and I got to sail closehauled in 20 knots of wind and 1.5 metres of waves.
Sigh!
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