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Old 14-07-2021, 23:02   #256
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Re: Replace Diesel with electric engine

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Originally Posted by jack4566 View Post
So I'm jumping into this discussion with a question for anyone who has done the math.


Is there any weight savings of electric?

Purely looking at sailing performance, lighter is faster right?
On one side you have diesel:
200kg+ diesel long block
200kg+ fuel tanks
50kg in spare parts, filters, auxiliary cooling pumps, etc.

And on the other you have electric:
20kg motor
50-200kg in batteries (which you had already)
10kg in extra wiring and control systems.


So potentially cutting 2-3% off your displacement. That's gotta count for something.

You simply forgot the 4 AAA monocells for the electric propulsion.
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Old 14-07-2021, 23:16   #257
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Re: Replace Diesel with electric engine

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Norbu09...I have no suggestions, but I must ask WHY would you want to replace the diesel engine with electric??

Because of supervised thinking and the lie that e propulsion will save the planet but has itself a footprint ratio of 1,5 against a diesel.



What you have was already harmful.
When you throw it away it damnifies the planet.
When you buy something new you set another footprint.

But if you repair what you have you minimize the damage to at least one tenth.
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Old 16-07-2021, 21:06   #258
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Re: Replace Diesel with electric engine

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Originally Posted by moseriw View Post
Because of supervised thinking and the lie that e propulsion will save the planet but has itself a footprint ratio of 1,5 against a diesel.



What you have was already harmful.
When you throw it away it damnifies the planet.
When you buy something new you set another footprint.

But if you repair what you have you minimize the damage to at least one tenth.
You believe that we supervise your thinking? Posting yes, thinking no.
EP won't save the planet but it will slow the rate at which it gets worse.

EP has a bigger footprint on the front end because the supply chain has not yet matured. Even if this never improves, the CO2 savings save way more on the back end in reduced fuel use than diesel.

I can see the argument that existing diesels should be run and maintained until they die.

But, once they are dead, they should be replaced with EP.
In the long run there will be ammonia or hydrate fuels to ASSIST solar and wind wind, but boating is going to move to something other than fossil fuels and motoring speeds will decrease, even for major shipping.
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Old 16-07-2021, 22:19   #259
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Re: Replace Diesel with electric engine

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Originally Posted by zloitapok View Post
Hello everyone posted in this thread and read it)
Thanks stevenm2016 for your post, one practical experience post cost a hundreds theoretical posts.
Also thanks all other ppl who share their experience with EP speed/power, regen power, etc.

I started to use EP at boats from 2017 and converted two small boats to electric inboards and one old gasoline outboard to electric one.
Also, I have derived a rough mathematical formula to calculate power/speed curves for provided hull params - thanks Fraud and some my observations.

I was not able to check my results at heavy boats and probably calculated data have inaccuracy at power > 20 kW

But for small and medium boats it work well. Hope this will help someone.
I assume is used large effective props.

Now it may be that I missed something in the thread, but I noticed that your data shows approximately a doubling of KW energy usage per increased forward velocity. This seems to hold across all models you listed, not just an loss of efficiency, but actually a predictable halving of it per additional single knot. Does this function hold steady across all displacement hulls, or has anyone else tried this? Researched it? I just find it interesting that the function holds one knot to hull speed, on a per-knot interval. Interesting!
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Old 17-07-2021, 00:05   #260
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Re: Replace Diesel with electric engine

Adelie: aggree - partly. but I think it will be syntectic fuels in the short and maybe a future solution to burn hydrogen directly without transfering the energy 4 times before it makes the required power. And this would be an combustion engine too.

No the problem is how we can produce enough electrical energy and not the battery storage. Maybe solar panels on every roof will be the solution - maybe not.

Standard housekeeping needs around 10 Kw/week and usual yearly milage is around 10.000 km (for Mid Europe), Range 300 km with 80 kW = 2660 kW p.a. / 52 = 51,3 kW/week.

By this, we would need 5 times as much energy as we require now.

And on a boat? - To harvest the eneergy for electric propulsion one needs around 800 m² of panels or a genset. Hmm I get the energy from a combustion engine to live my dream?
How crazy is that?


OK, if you have a boat of 1,5 tons on a lake everything is fine and this is, sometimes due to regulastions - the only solution and it works beeing plugged in every night. But on a bluewater cruiser on the long run?


No problem at all - I HAVE OUTLETS!!!
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Old 17-07-2021, 00:38   #261
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Re: Replace Diesel with electric engine

Climate change:
Litte ice ages: 1350, 1630, 1810,??? climatologists say 2024 to 2050 will be the next one.
Big drought: 1530 - almost all rivers in Europe were dry

300+ climatologists singed a petition to confirm climate change but deny the proof of human involvement. Why?

It is possible to remove CO2 out of the air. The expense is low the chemical process known since ages. We, the people, do not know it. Why?
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Old 17-07-2021, 04:52   #262
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by moseriw View Post
Adelie: aggree - partly. but I think it will be syntectic fuels in the short and maybe a future solution to burn hydrogen directly without transfering the energy 4 times before it makes the required power. And this would be an combustion engine too.

No the problem is how we can produce enough electrical energy and not the battery storage. Maybe solar panels on every roof will be the solution - maybe not.

Standard housekeeping needs around 10 Kw/week and usual yearly milage is around 10.000 km (for Mid Europe), Range 300 km with 80 kW = 2660 kW p.a. / 52 = 51,3 kW/week.

By this, we would need 5 times as much energy as we require now.

And on a boat? - To harvest the eneergy for electric propulsion one needs around 800 m² of panels or a genset. Hmm I get the energy from a combustion engine to live my dream?
How crazy is that?


OK, if you have a boat of 1,5 tons on a lake everything is fine and this is, sometimes due to regulastions - the only solution and it works beeing plugged in every night. But on a bluewater cruiser on the long run?


No problem at all - I HAVE OUTLETS!!!

What are "syntectic fuels "?
Hydrogen has too many down sides to be practical unless they can find an efficient way to store them as hydrates. Energy penalty to pressurize or liquify. Weight penalty to storage as pressurized gas or cryogenic liquid.
It has great specific energy (kW/kg) but poor energy density (kW/liter).

You don't need 800m² of panels to power a vessel. There is at least one example of a 40' power catamaran that used 58m² which was able to run 4kt 24/7.

For a bluewater cruiser EP works because one doesn't have a schedule to keep, so sitting when there is no wind or proceeding at 1.5-2.5kt using available solar is acceptable. It's the coastal cruisers who are out for a week or a weekend that need to be back for work on Monday for whom solar is not enough.
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Old 17-07-2021, 04:57   #263
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by SailingFan View Post
Now it may be that I missed something in the thread, but I noticed that your data shows approximately a doubling of KW energy usage per increased forward velocity. This seems to hold across all models you listed, not just an loss of efficiency, but actually a predictable halving of it per additional single knot. Does this function hold steady across all displacement hulls, or has anyone else tried this? Researched it? I just find it interesting that the function holds one knot to hull speed, on a per-knot interval. Interesting!
The curve don't show a doubling in power required for every extra knot of boat speed, but that's not far off the truth, power requirements a very non-linear except at very low speeds.

I vaguely recall getting this graph from Skene's but I don't recall accurately:
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Old 17-07-2021, 06:06   #264
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Re: Replace Diesel with electric engine

58m² which was able to run 4kt 24/7.


Ok, let us calculate: my panels with 2,7 m² make 18 Amp at maximum. I consider 12 hrs = 18 x 12 hrs = 216 Ah x 12 = 2,5 kW/day. I want to run at 20 kW/h but reduce to 10 kWh. Thus will get me max 2 knots with my 20 metric tons 14m boat.

Catamaran with 58 m² x 77Ah/day/m² = 4466 Ah/day * 12 = 53 kW/Day whereof 26 kW have gto be stored in batteries.

I accept it and need 10 kW/h x 24 = 240 kWh/day
My solar panels have to be at a size of: 216A / 2,8 = 77 Amps = 0,924 kW/m²

240 000 / 0.924 = 259,74 m²

OH I am sooo sorry I was wrong with the 800 m².

On the other hand: if the panels of this fantastic cat make 240 Ah /12 hrs:
I WANT THE PANELS! PLEASE!!!
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Old 17-07-2021, 06:12   #265
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Re: Replace Diesel with electric engine

OK I should not use Amps and Volts in this calculation. OK if someone has another calculation...
My panels have 420 Wp and make 18A Ok say we harvest an average at 24 V 18 x 24 =

Oh man I am tired of this scarp because there is one thing that is true: IT IS NOT ENOUGH
especially in the tropics where you never have sun enough to get the max out as it is 80% cloudy which drops you to < 20% of the said WattPeak WP.
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Old 17-07-2021, 07:26   #266
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by moseriw View Post
58m² which was able to run 4kt 24/7.


Ok, let us calculate: my panels with 2,7 m² make 18 Amp at maximum. I consider 12 hrs = 18 x 12 hrs = 216 Ah x 12 = 2,5 kW/day. I want to run at 20 kW/h but reduce to 10 kWh. Thus will get me max 2 knots with my 20 metric tons 14m boat.

Catamaran with 58 m² x 77Ah/day/m² = 4466 Ah/day * 12 = 53 kW/Day whereof 26 kW have gto be stored in batteries.

I accept it and need 10 kW/h x 24 = 240 kWh/day
My solar panels have to be at a size of: 216A / 2,8 = 77 Amps = 0,924 kW/m²

240 000 / 0.924 = 259,74 m²

OH I am sooo sorry I was wrong with the 800 m².

On the other hand: if the panels of this fantastic cat make 240 Ah /12 hrs:
I WANT THE PANELS! PLEASE!!!
1m² of panels produces about 220W, or about 72.6Arh/d which equals 871Whr/d.
58m² would produce about 50.5kWhr/d. Assuming no storage losses that's 2.1kW.
2.1kW produces about 70lb thrust. (Yes, yes, I know I'm mixing units from different systems, get over it.)
1t metric is pretty much equal to 1 long ton.
70lb / 20t = 3.5 lb/t.
From the graph that means that speed would be somewhere around .5-.6 * sqrt LWL
Let's assume your vessel has an 11.5m (38') waterline.
0.5 * sqrt (38) = 3.1kt. 24/7 using 58m² of panels to propel your boat.

You should be getting about 220w/m². For 2.7m² that would produce about 594W / 12v = 50A at noon in full sun. A daily production of 196Ahr/d is in the ball park of what your state, 216Ahr/d.
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Old 17-07-2021, 10:38   #267
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Re: Replace Diesel with electric engine

Should you stream "Sailing Uma' and "Wisdom Sailing" on you tube you will find that they are becalmed with dead batteries. "Uma" mentions that they do need a generator.
These are real-world cruisers' experiences.
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Old 17-07-2021, 11:25   #268
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Re: Replace Diesel with electric engine

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Originally Posted by bgallinger View Post
Norbu09...I have no suggestions, but I must ask WHY would you want to replace the diesel engine with electric??
There are some advantages in having an electric motor. First, diesel and gas engines, and electric motors each have advantages. I personally prefer a diesel but am interested in electric motors also. I may even convert one of my sailboats to an electric motor.

Some of the electric motor advantages are:
1. It is quiet. There is virtually no noise.
2. The motor itself requires very little routine maintenance. The battery and electrical system however requires more.
3. The electric motor is usually smaller and lighter than a diesel of comparable power. While it is true that one often need a bigger battery bank, the bank can often be more conveniently placed in the boat. In a full keel yacht for example, the batteries are often placed lower than an engine thus adding stability.

4. An electric motor is typically runs cooler which is a big advantage in warm climates.
5. With sufficient power generation (solar, wind turbines, water generators) one can motor if necessary without the need to worry about running out of diesel, even in the middle of oceans. This typically favors larger yachts when relying upon solar.
6. If using a generator to charge the batteries, the genset can run at the optimum RPM for increased efficiency. This is similar to the way diesel-electric locomotives work.

Having said all this, there are of course, disadvantages too. N.B. I am not listing these to disparage electric motors in boats, rather only to present a balanced view. A few of these include the expense and complexity of the required battery bank and the charging systems, the loss of residual heat for things such as hot water and heating the cabin in the high latitudes, battery life, the need for a larger battery bank, etc.

Cruising can be done, and it can be done practically. The reality is that each system has to be matched to the sailing that one is doing as well as the personal tastes, etc. It's not a question of which system is better as one is not better than the other. It is a question of which system is better suited for you. Which system satisfies your wants and needs.
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Old 17-07-2021, 12:01   #269
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Re: Replace Diesel with electric engine

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Originally Posted by Scaramanga F25 View Post
Should you stream "Sailing Uma' and "Wisdom Sailing" on you tube you will find that they are becalmed with dead batteries. "Uma" mentions that they do need a generator.
These are real-world cruisers' experiences.
Funny you should mention Uma. I watched the latest episode 3hr ago. Yes they were having issues with the electric drive, because they were sailing in high latitudes (above the arctic circle) off or shoulder season (April). It was an unusual choice that wasn’t thought through completely or they did think it thru and chose to go anyway knowing it was marginal and might work out. They pointed out in this episode that for tropical and temperate sailing on-season and shoulder season they were quite happy with the system.

Wisdom’s situation is somewhat different, they are traveling up the ICW which is constrained for sailing for a significant fraction of the time. Not that one can’t do it , Boat Alexandra proved that. Distance between anchorages is likely a constraining issue in places, with 35-40nm to go they may not have the range at the speed required to make the distance during daylight hours. They may have a schedule to meet, at the very least they need to beat hurricane season home to MD. In order to better make the trip they are upgrading their battery bank with DIY LiFePo. I haven’t seen their latest video so I don’t know what other preparations they are making to provide more energy. They too have indicated satisfaction with their EP and accept that special destinations will involve changes to their existing system that has worked well until now.

My opinion is that neither boat has gone all in on solar. Yes they both have significant solar but both could almost double what they have by building a cockpit Bimini with solar panels.
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Old 17-07-2021, 12:27   #270
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Re: Replace Diesel with electric engine

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Originally Posted by ArmyDaveNY View Post
…..
6. If using a generator to charge the batteries, the genset can run at the optimum RPM for increased efficiency. This is similar to the way diesel-electric locomotives work…….
Locomotives use diesel electric because there is not effective mechanical transmissions when a train becomes very long and heavy. Mechanical transmissions just don’t hold up when trying to start a train from a full stop. D-E is used on ferries because they can be throttled and reversed quickly. Cruise ships use it because they have very large ships that may need to pull in at destinations that do not have tug services so bow thrusters and Azi-pods are needed to dock.

The losses involved in converting mechanical power to electricity and back easily outweighs any efficiency gains from operating the prime mover at its optimum RPM.

Where a combustion engine is an auxiliary energy source then using a series hybrid system makes sense for a small vessel. For cruisers this would be like using a Honda 2200EU occasionally. If used continuously it would be able to propel a boat of about 34’ at 4kt. Where an engine is a major energy source or the prime mover it makes more sense money and efficiency wise to use a parallel system where the engine is connected to the prop. This would be appropriate for crossing the doldrums or running the ICW on a schedule.
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