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Old 09-08-2021, 01:22   #331
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Re: Replace Diesel with electric engine

Using EP 5+ years. I don't know exactly if I produce more footprint than diesel. My solar panel generate energy enough for 10 miles at motor every day and I have a 60 miles range at batteries only. I don't use genset for 2,5 last years. I go sailing for 150 nm eventually using sails or slow electric moving in calm, but mostly it is a <30 miles trips, which I travel at hull speed at motor.

EP have it purpose and it is not a 100% replacement for diesel yet.
But it is very funny when diesel boats need a motor service and warming up the engine, don't start for unknown reason, have a waste at fuel tank, etc. etc.
I have a limited range at motor, but it is very reliable and trouble-free range, if I can say so. For years using EP I changed one hall sensor at motor for $3
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Old 09-08-2021, 01:22   #332
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Re: Replace Diesel with electric engine

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Unless you are a day sailor and never get more than 5 miles from your home port or are someone willing to sit on your boat until the wind comes up electric drive from battery and solar just won't work.
How did the solar boat circumnavigate if "electric drive from battery and solar just won't work" I have had electric from solar in various forms for a while.

I can motor on 120 watts at 2 knots. I can generate a lot more than this from solar. Typically you dont have go get very far to reach wind if you are actually without wind. Since my boat sails the wind speed, in 2 knots of wind the sails will take over. It is very rare to have less than 2 knots of wind. Even a slight current will generate an apparent wind.

I can make just about every passage a lot faster than most displacement boats even if they have a big engine.
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Old 09-08-2021, 01:30   #333
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Re: Replace Diesel with electric engine

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I own a Tesla model 3. I plug it into the power grid every night. I can go to a charging station and put 40 KW into the battery in less than half an hour. There are no super chargers in the ocean.
I plug ebike into same solar panels on boat. It charges in 2-3 hours using 80 watts. Charging in half an hour is not very efficient especially doing it at night when there is no solar.

I use 10-15 watt hours per mile and go 18 miles. Tesla use 250 watt hour per mile so emissions are only half a normal car overall which isnt good enough. There are electric cars that use half the energy and resources of tesla.

It is clear your choices are not very energy efficient ones: no wonder you dont think solar electric is not possible when it actually is.
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Old 09-08-2021, 01:43   #334
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Re: Replace Diesel with electric engine

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How did the solar boat circumnavigate if "electric drive from battery and solar just won't work" I have had electric from solar in various forms for a while.

I can motor on 120 watts at 2 knots. I can generate a lot more than this from solar. Typically you dont have go get very far to reach wind if you are actually without wind. Since my boat sails the wind speed, in 2 knots of wind the sails will take over. It is very rare to have less than 2 knots of wind. Even a slight current will generate an apparent wind.

I can make just about every passage a lot faster than most displacement boats even if they have a big engine.
Please tell us the economics of the solar boat. I seem to recall seeing pictures of it with a flat deck of nothing but solar panels. As a proof of concept I'm sure it was great. How practical was it? How much did it cost to build?

A Crowther 33 is a very light boat. I'm sure it is a great performer. I'll also bet that the ride is like a bucking bronco. Multihulls are very weight sensitive, why have any engine?

Sailing from Hawaii to Canada we had about ten days of no wind. Wasn't happy to motor but would have been less happy to sit still.
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Old 09-08-2021, 01:55   #335
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Re: Replace Diesel with electric engine

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Originally Posted by seandepagnier View Post
I plug ebike into same solar panels on boat. It charges in 2-3 hours using 80 watts. Charging in half an hour is not very efficient especially doing it at night when there is no solar.

I use 10-15 watt hours per mile and go 18 miles. Tesla use 250 watt hour per mile so emissions are only half a normal car overall which isnt good enough. There are electric cars that use half the energy and resources of tesla.

It is clear your choices are not very energy efficient ones: no wonder you dont think solar electric is not possible when it actually is.
Where I live we have a lot of hydro-electric power. The water flows 24/7. Half the carbon footprint of an ICE car is bad???

I never said EP was not possible, obviously it is. I said it is not practical. I also said that it would destroy the resale value of the boat. Call a yacht broker and ask about selling an EP Super Maramu without a huge diesel generator. See what they say - probably tell you to put in a diesel or forget about selling it.
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Old 09-08-2021, 04:35   #336
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Re: Replace Diesel with electric engine

So EVERY car manufacture on the planet making the switch has it all wrong? Hmmm, don't think so.



In ten to fifteen years when the price of diesel will be in the $10 a gallon range due to low production and carbon taxes everyone will be switching their boats to electric. Watch and see...
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Old 09-08-2021, 04:50   #337
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Re: Replace Diesel with electric engine

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So EVERY car manufacture on the planet making the switch has it all wrong? Hmmm, don't think so.

In ten to fifteen years when the price of diesel will be in the $10 a gallon range due to low production and carbon taxes everyone will be switching their boats to electric. Watch and see...
Will outside influences force cruisers to accept an inferior drivetrain? Maybe but in the short term, it will likely drive down fuel prices. Car manufacturers aren't converting because electric vehicles make more sense for the market, they are reacting to the political pressure and the political rules that come with it.

But to the question about car manufacturers being wrong demonstrates a common misunderstanding of the engineering. Cars and displacement cruising boats have wildly different power demands.
- Cars in city traffic fluctuate from zero power to peak power demand and cycle thru every 30-120 seconds as they stop at intersections. That works great with hybrid and battery electric as they lose little to nothing while sitting at a stop light and they can recover power thru regenerative braking every time they stop. It allows substantially more efficient use of limited energy sources. Also, starting up, the ability of electric motors to provide maximum torque from zero RPM, means electric motors can put out higher horsepower sooner. At actual cruising speed, most small cars only need 40-60hp. They put in 120-200hp gas engines to make up for the low HP output at lower RPM...that's not needed for electric motors.
- Your average displacement cruising boat gets up to speed and runs at a steady power output for several hours. The power needed is the power needed. Acceleration isn't a big priority but even then since the prop can slip in the water and spin up faster before accelerating the boat, there really is negligible impact having more low end torque.

So you are asking the wrong question.
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Old 09-08-2021, 05:34   #338
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Re: Replace Diesel with electric engine

PWP misread my post about speed at WOT and thought I was asking about the main engine.

Like I said, it’ll take about 10hp at the motor for Jedi to make 6kt.

Regen is a very slow way to recharge the batteries. That doesn’t mean it’s a fraud, just means it’s slow.

And you need to look at your math again.
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Old 09-08-2021, 05:40   #339
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Replace Diesel with electric engine

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Originally Posted by moseriw View Post
Uaaarghh, I am really getting tired of EP. Everyone believes in it like in the immaculate Conception. As backpack a few AAA Monocells and the remaining will be done with recuperation.



Look at the capabilities of your bowthruster. See how slow it moves the boat.

Did you know that is has got 6 Kw?



So how can someone believe in 10 Kw?


I just figured out your AAA & recuperation phrase. You are trying to be sarcastically funny and failing on both counts. This is the 3rd or 4th try. It’s not working.



Your bowthruster analogy has merit though. 6kW to move the boat sideways at 2kt vs 7.5kw to move it forward at 6kt sounds about right. Good comparison.
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Old 09-08-2021, 08:03   #340
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Re: Replace Diesel with electric engine

Thanks for the feedback.

Let me clarify. I may re-power the boat conventionally and also add a Gen Set (boat does not have one now) or go hybrid.

Either way, I'll only consider options which give me at least 4HP per ton. So at least 100HP or approx 85-90KW. I will also, only consider options which give me at least 600NM range under power. I have 200 Gallons of dinosaur juice currently.

If the hybrid proposal does not meet my needs, I'll go conventional.

It's interesting and noteworthy that a long established and very well regarded commercial and recreational yacht yard has done numerous installations and think it's worth looking at.

When I have a proposal, I can share more. Right now, all I know is that there's a possibility to consider.

BTW, the GenSet is Cummins not BAE and the Electric motor is HybridMarine. Both well established companies. BAE makes the controllers and inverters etc.
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Old 09-08-2021, 08:33   #341
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Re: Replace Diesel with electric engine

100hp is 75kW.

600nm at what speed and in what wind and sea conditions?
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Old 09-08-2021, 11:02   #342
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Re: Replace Diesel with electric engine

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Jedi is 64’, 55,000lbs (25 metric tons) and currently has a 140hp Yanmar 4 cylinder auxiliary motor.

If the engine wears out it will be replaced with electric, no question about it. For continuous motoring I would be happy with 6kts from a genset. For hull speed I would be fine with genset + batteries for 30 minutes and happy with 1 hour.

I can’t imagine ever needing more than that. I believe I can get 6kts out of my 20hp outboard if I rig up a mount (am surely gonna try that as well).

Of course we normally sail. I rather wait for wind for a week than motor today.
That's 100% my thoughts of how to use an electric driven S/V. Yes, 20hp outboard should be enough for 6 kts (with appropriate pitch in calm weather).
My plans are 2x13kW for a 42ft catamaran. She will need about 5kW in calm, can push 1000 lbs for 45 mins in emergency (80%SoC + genset). She'll have 8 or 10kVA genset for the long run.
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Old 09-08-2021, 11:25   #343
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Re: Replace Diesel with electric engine

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Originally Posted by EngineerRetired View Post
In ten to fifteen years when the price of diesel will be in the $10 a gallon range due to low production and carbon taxes everyone will be switching their boats to electric. Watch and see...
Indeed. I see the US President has committed the country to reduce emissions to 50% by 2130. The UK has pledged to stop purchases of new petrol and diesel cars by the same date.

Now petrol and diesel will be around for a while yet. However, the price you have to pay for it, well that might come as a shock. After all if you were the politician charged with persuading people to give up ICE cars what would you do, increase fuel taxation perhaps? Governments don't even have to do anything, fuel suppliers collect and pass to the Gov.

I wouldn't want to buy a Miami Vice power boat for the long term

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Old 09-08-2021, 11:48   #344
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Re: Replace Diesel with electric engine

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Originally Posted by wingssail View Post
The reason the question came up is because we were trying to image how many kilowatts (hp) was needed for studentdriver's Empacher 52 (like he wanted to put in a 100kw genset so he can achieve his desired speeds (LOL)).

But Jedi is a good test case to start getting some ballpark figures.

When we look at hp/prop curves we see very shallow slope down low, getting steeper as speeds go up. I know from the published curves for my motor, and from actual fuel usage measurements, that 6 knots requires around 11hp at the prop and approx 22 hp output from the engine itself (that is 2200 rpm on my 3JH Yanmar).

I guess that the Sundeer 64 is going to take twice that. Jedi says no, just 20hp, but he has not told us the rpm he needs to use for six knots, or the fuel usage.

studentdriver wants to put 100kw gen set on his imaginary project, which is a bit too far the other direction. Probably needs about 35hp or about 40kw.

It all goes back to how big of an electric drive system one needs to be able to maintain 6 knots continuously running an electric motor on the output of a genset.

And this leads us to think about the regen issue. If it takes 35 shaft HP (40kw) to push the boat six knots, then it would take (forgetting losses) the equivalent of an extra 35HP on the sails to extract 40kw in regen mode. (wow, that would be good, 40kw is 3000 amps at 12 v, 800 amps at 48v!) but the total drive required is equivalent to 70 hp on the sails. Hard to see when that is going to happen. So regen is a fraud.

The only way your engine will produce 22HP at 2200 RPM is when you're so severely over-prop'd it requires WOT just to reach 2200. If you can reach 3000 @ WOT, you will be at partial throttle @ 2200, and the P-D curve is the best predictor for your actual HP output there, and pretty much mirrors the fuel flow curve.

Re-gen is not a fraud to those who use it effectively I've read about, but generally needing more than 5kt sailing speed, and will obviously be less output than the amps needed to push you to that speed.
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Old 09-08-2021, 12:45   #345
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Re: Replace Diesel with electric engine

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The reason the question came up is because we were trying to image how many kilowatts (hp) was needed for studentdriver's Empacher 52 (like he wanted to put in a 100kw genset so he can achieve his desired speeds (LOL)).

But Jedi is a good test case to start getting some ballpark figures.

When we look at hp/prop curves we see very shallow slope down low, getting steeper as speeds go up. I know from the published curves for my motor, and from actual fuel usage measurements, that 6 knots requires around 11hp at the prop and approx 22 hp output from the engine itself (that is 2200 rpm on my 3JH Yanmar).

I guess that the Sundeer 64 is going to take twice that. Jedi says no, just 20hp, but he has not told us the rpm he needs to use for six knots, or the fuel usage.

studentdriver wants to put 100kw gen set on his imaginary project, which is a bit too far the other direction. Probably needs about 35hp or about 40kw.

It all goes back to how big of an electric drive system one needs to be able to maintain 6 knots continuously running an electric motor on the output of a genset.

And this leads us to think about the regen issue. If it takes 35 shaft HP (40kw) to push the boat six knots, then it would take (forgetting losses) the equivalent of an extra 35HP on the sails to extract 40kw in regen mode. (wow, that would be good, 40kw is 3000 amps at 12 v, 800 amps at 48v!) but the total drive required is equivalent to 70 hp on the sails. Hard to see when that is going to happen. So regen is a fraud.
Regen of 35kW @12V??? What are you talking about?
1st 35kW EP needs 96V (probably 48V with a really fat cable).
2nd (and most important) - props are usually optimized for one direction - forward.
3rd The prop-slip has to be compensated too. Means you need a lot more speed under sail.

In real life regen is about 10-15% of the nominal forward power.
But that is totally o.k. @5-6 kts sailing speed. Sailing 24hrs and regen with 3 kW produce over 80 kWh per day. That is probably more than the battery capacity - even with a wash day or a 4 course menu with induction cook top and convection oven...
(BTW - 80kWh battery capacity weighs about 700kg!)
As Jedi said - 1/2 hour of nominal output would be o.k. That leads to about 20 kWh capacity) and needs less than 1kW regen power.
It is also wrong to only compare HP or kW numbers. 20kW on the shaft of an electric motor are (almost) 40HP ICE performance designation.
It makes no sense to throw half-truths around.

Regen is not a fraud!
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