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Old 28-01-2020, 12:36   #31
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Re: Replace Diesel with electric engine

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Since there is a propeller shaft in the boat with nothing attached, I'm putting in an electric drive for fun to see what it can do. I already have all the parts. The motor cost $50 (free shipping) is 2800 watt brushless motor with rare earth magnets. The gear reduction using chain and belt (2 stage) This cost $30 in total because you can 3d print the pulleys. The controller cost $23 on ebay, and it uses 24 volt 40ah lithium iron battery cost $600. Will be interesting to see the performance, it is likely 3-4 knots speed and 10-12 miles going slowly with 250 watts solar to recharge.
Could you please provide the motor specs? So, you're going to power a motor that will draw over 100 amps with a 40 ah battery? Granted, the right LiFePo cell pack can certainly handle the discharge rate, but how do you expect to get 3 to 4 hours run time out of it?

Not to mention that I believe you're talking about a motor used for model planes and drones...
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Old 28-01-2020, 12:39   #32
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Re: Replace Diesel with electric engine

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Could you please provide the motor specs? So, you're going to power a motor that will draw over 100 amps with a 40 ah battery? Granted, the right LiFePo cell pack can certainly handle the discharge rate, but how do you expect to get 3 to 4 hours run time out of it?

Not to mention that I believe you're talking about a motor used for model planes and drones...
He is adding a motor controller, that can limit power consumption to however small you want. If he limits it to 10 amps then he gets 4 hours. The speed of the boat and distance traveled is what differs.
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Old 29-01-2020, 01:07   #33
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Re: Replace Diesel with electric engine

We've had our '14 Greenline 33 Hybrid m/v "Swan Song" - hull #301- for about 7 months now, after nearly 60 years of sailing. Both turning 80 this year, in better than average shape, but not up to the frequently challenging Pacific coastal sailing conditions any more. An October 750 mile round trip to the Channel Islands proved her seaworthiness and comfort at 9-10kts (14 max).

She has a 165 HP VW turbodiesel with an in-line 7/5Kw motor/gen. and an electro-hyd. clutch for an either/or choice of power. The 48V/240Ah, 12KwH LiPo battery gives a max speed of 6kts drawing 150A, with a 17" five-bladed prop, 2:1 reduction. WL is 32.5' for hull speed of about 7.4kts. Range ~10nm in flat conditions wide open, or ~20nm @ 4kts. We have 480W solar and all appliances 120V, with full-time 120 from the 3000W Victron inverter/converter/charger...with or without shore power. The beauty of it is that you can hang on the hook for several days without engine charging- even with liberal use of appliances - if you start with a good charge in the battery.

The downside, though, is a wildly complex system with a variety of gray sealed boxes sprouting small and large wires, with incomprehensible schematics. if something goes wrong in one of those, thank the graces the old reliable diesel is ready to go - and I speak diesel fluently!

We enjoy using the hybrid power whale watching after dieseling out to find them; for getting into and out of Moss Landing, Monterey, or Santa Cruz harbors; and sometimes just laying back and running the last 5-10 miles back at 5kts or so. But when it gets dicey it struggles, like the other day coming into Moss Ldng. against a 2.5-3kt max-ebb flow meeting the 6-7' prevailing westerly swells. There was a long patch of confused ~3' standing waves trying to trap us, slowing us to 2-2.5kts full power. Of course we could have quickly fired the diesel....

So I have to wonder how the OP's plan will work out with his large, heavy vessel and its huge wetted surface area in any but benign conditions with clean hull - even with 4X the electric motor power and battery cap. we have. His ~800A current draw at max. will need enormous, short cabling, which is why hybrid autos use much higher voltages, eg. 288V to my Highlander hybrid's ~34Kw motor.

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Old 29-01-2020, 02:25   #34
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Re: Replace Diesel with electric engine

Hi Pete, this is a really interesting point you make as you have both and can compare them side by side. Thanks for the long post explaining your setup and experience.
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Old 29-01-2020, 06:12   #35
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Re: Replace Diesel with electric engine

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Thanks everyone for your insights and the worries everyone shares about us and our travels.
In terms of regen, Amel has put an alternator sitting on the prop shaft for generating electricity factory sides already. The Prop is a MaxProp that can "push" and "pull" and the setup is working pretty well under sail from around 5 knots onward. Based on that we think that the electric engine should work well on regen too, may need higher speeds though.
I’ve used prop shaft driven alternators on several boats

Nice system ..perhaps 6 knots min . Plenty of alternator output

Remember that when you generate many rotational hours on the prop shaft you increase wear on seals etc ..

The boats I sailed also has thrust, saddle bearings on the prop shaft to handle the various non standard loads
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Old 29-01-2020, 16:56   #36
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Re: Replace Diesel with electric engine

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I’ve used prop shaft driven alternators on several boats

Nice system ..perhaps 6 knots min . Plenty of alternator output

Remember that when you generate many rotational hours on the prop shaft you increase wear on seals etc ..

The boats I sailed also has thrust, saddle bearings on the prop shaft to handle the various non standard loads
25 years ago we were sailing our FP Antigua 37 off Costa Rica in a particularly rough short sea at maybe 7-8knts, with the Yanmar 18hp saildrives swinging 3-blade 16" Max Props feathered with reverse gear. Suddenly there was a loud RUMP! RUMP! RUMP!... repeating sound, vibrating the boat - thought we had hit and dragged something bumping the hull.

We depowered the sails, and it quit. Turns out the port prop had somehow un-feathered in the rough water and was turning over the engine with the "backwards" mechanical advantage of the 2.??:1 reduction gear! Some kind of power, even with the relatively inefficient flat blade design.
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Old 29-01-2020, 17:14   #37
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Re: Replace Diesel with electric engine

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Hi Pete, this is a really interesting point you make as you have both and can compare them side by side. Thanks for the long post explaining your setup and experience.
You're welcomed! The control system for the Greenline's 48V LiPo, four12V AGM's, and 120VAC shore power is primarily Victron, and if you like I could copy their overall schematics diagram for you.

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Old 29-01-2020, 20:50   #38
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Re: Replace Diesel with electric engine

While you've obviously put a lot of work into the battery part of the design, you've apparently not thought as much about the source of power.

Using a diesel generator to charge batteries and then use them to power a propeller shaft is much less green than connecting a diesel engine directly to the same propeller shaft. That's because basic science says you lose energy every time you convert it to a different form. The diesel genset will burn about 30%-40% more fuel per mile - definitely not green.

Of course, this isn't a problem if you hardly ever run the genset - as you plan. You have two sources in mind:

Solar - On a monohull it is very difficult to find enough unshaded deck space to simply do hotel loads (lights, refrigeration, etc.). And Amels with their ketch rig have very little unshaded deck space. I can assure you, there will not be any solar power left over for the engine.

Water generator (what you call "regen") - These can generate quite a bit of power but in practice on small boats they produce less than a few solar panels. Perhaps you can find one that generates enough to charge that battery bank but I can assure you it's not the one from Amel. Finding one that does seems to be your primary problem.

1 hp = 745 watts. I would guess you'll need about a 20hp electric motor to make that Amel go 5 knots. That motor will draw 15,000 watts. If you want to use the engine for just three hours, you'll need to pull 45,000 watt/hrs from the batteries. That means you'll need about 65,000 watt/hrs of charge since batteries have a substantial "round trip" loss in a charge/discharge cycle. That's a really big number.

If you can't generate that much power from the water generator and have to start the genset, this whole exercise is pointless - at least from the "green" perspective.
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Old 29-01-2020, 21:09   #39
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Re: Replace Diesel with electric engine

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While you've obviously put a lot of work into the battery part of the design, you've apparently not thought as much about the source of power.

Using a diesel generator to charge batteries and then use them to power a propeller shaft is much less green than connecting a diesel engine directly to the same propeller shaft. That's because basic science says you lose energy every time you convert it to a different form. The diesel genset will burn about 30%-40% more fuel per mile - definitely not green.

Of course, this isn't a problem if you hardly ever run the genset - as you plan. You have two sources in mind:

Solar - On a monohull it is very difficult to find enough unshaded deck space to simply do hotel loads (lights, refrigeration, etc.). And Amels with their ketch rig have very little unshaded deck space. I can assure you, there will not be any solar power left over for the engine.

Water generator (what you call "regen") - These can generate quite a bit of power but in practice on small boats they produce less than a few solar panels. Perhaps you can find one that generates enough to charge that battery bank but I can assure you it's not the one from Amel. Finding one that does seems to be your primary problem.

1 hp = 745 watts. I would guess you'll need about a 20hp electric motor to make that Amel go 5 knots. That motor will draw 15,000 watts. If you want to use the engine for just three hours, you'll need to pull 45,000 watt/hrs from the batteries. That means you'll need about 65,000 watt/hrs of charge since batteries have a substantial "round trip" loss in a charge/discharge cycle. That's a really big number.

If you can't generate that much power from the water generator and have to start the genset, this whole exercise is pointless - at least from the "green" perspective.
That’s not how it normally works. In a normal situation the motor runs from the batteries for short uses like exiting the marina, dropping anchor etc. When a long use of the motor is required, like during a calm, then the diesel generates electric power which feeds the electric motor. The power does not flow through the batteries at all.
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Old 29-01-2020, 21:31   #40
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Re: Replace Diesel with electric engine

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Originally Posted by CarlF View Post
....
Solar - On a monohull it is very difficult to find enough unshaded deck space to simply do hotel loads (lights, refrigeration, etc.). And Amels with their ketch rig have very little unshaded deck space. I can assure you, there will not be any solar power left over for the engine.

...

1 hp = 745 watts. I would guess you'll need about a 20hp electric motor to make that Amel go 5 knots. That motor will draw 15,000 watts. If you want to use the engine for just three hours, you'll need to pull 45,000 watt/hrs from the batteries. That means you'll need about 65,000 watt/hrs of charge since batteries have a substantial "round trip" loss in a charge/discharge cycle. That's a really big number.

...
If there is no wind and you need electric propulsion, then the sails will all or mostly be down and most of the deck will not be shaded.

That was a adequate guess on electrical requirements.
Based on 36,000 lb displacement, 41.34' lwl and 5kt speed, a 19hp ICE engine would be required which is just about 14kw. In reality it would be more like 10-12kw but not bad for a guess.

I used Boat Speed Calculator to figure this out.
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Old 29-01-2020, 21:52   #41
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Re: Replace Diesel with electric engine

Jedi,

You're right. I was just trying to stick with what is apparently his plan to use that huge battery bank. I expect in actual use it would normally be run as a diesel electric and the batteries would become the biggest Amel house bank in history.

As a diesel-electric he has a bit less energy loss (would you guess perhaps 20%?) compared to conventional diesel driving a shaft. The diesel is using rotational energy to make electricity and then the electricity is turned back into rotational energy by the electric motor after loosing a bit more in the wires and controller.

It's still a step back in "green".

Adelie - I wasn't even thinking of sail shading. Just mast, boom, and rigging shade is a b*tch on a ketch - I have one. 10% shading will drop out a solar panel completely.
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Old 29-01-2020, 21:57   #42
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Re: Replace Diesel with electric engine

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Originally Posted by Adelie View Post
If there is no wind and you need electric propulsion, then the sails will all or mostly be down and most of the deck will not be shaded.

That was a adequate guess on electrical requirements.
Based on 36,000 lb displacement, 41.34' lwl and 5kt speed, a 19hp ICE engine would be required which is just about 14kw. In reality it would be more like 10-12kw but not bad for a guess.

I used Boat Speed Calculator to figure this out.
For every hour of motoring electric propulsion will need many many hours of solar charging. The power produced while motoring would be insignificant. Even in ideal conditions, with 2KW of solar it would take a full day to produce enough power to motor one hour.
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Old 29-01-2020, 22:20   #43
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Re: Replace Diesel with electric engine

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Originally Posted by CarlF View Post
...
As a diesel-electric he has a bit less energy loss (would you guess perhaps 20%?) compared to conventional diesel driving a shaft. The diesel is using rotational energy to make electricity and then the electricity is turned back into rotational energy by the electric motor after loosing a bit more in the wires and controller.

It's still a step back in "green".

....
Compared to a diesel-transmission diesel-electric is much less efficient. If it weren't shippers would be using diesel electric. D-E is used in various applications for reasons other than efficiency.
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Old 29-01-2020, 22:28   #44
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Re: Replace Diesel with electric engine

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For every hour of motoring electric propulsion will need many many hours of solar charging. The power produced while motoring would be insignificant. Even in ideal conditions, with 2KW of solar it would take a full day to produce enough power to motor one hour.
I will agree that for the OP's boat, installing enough panels would be difficult if you wanted enough power for several hours of motoring. If on the other hand the goal is to be able to avoid a collision with another boat and to get in and out of harbors, electrical should be just fine.

On the other hand, for a smaller boat that is not the case.
I am looking at putting electric drive on a CAL-34. Based on my research I should be able to maintain 3kt on 1kw of panels. The motor supplier says 3.2kt on 960w and 2.5kt on 480w.
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Old 29-01-2020, 23:54   #45
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Re: Replace Diesel with electric engine

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Regarding sail power in a marina scenario that is very often not possible. Most of the docks and marinas I stop at are in protected areas like far inside a harbor, sometimes inland on a river. Some of the harbors are surrounded by high hills which can block winds altogether or result in winds that are light, extremely variable and unreliable. In the situation I mentioned there was little wind at all.
This is a perfect of example of where an electric motor would be convenient for the OP or where I utilize a sculling oar for a few minutes.

Regarding light and variable winds: catch each puff of wind and anticipate shifts in advance. Was very useful the 3 times I sailed through the dismal swamp when the wind was forward of the beam as sometimes it was directly on the nose. Because of shifting wind direction and anticipation it was possible even in such narrow canals. Twice in 20 miles the shift lasted too long and had to drop the head sail for a minute.

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Yes it is possible to sail the ICW but unless one has unlimited time to wait for the right conditions not very practical. Also long sections of the ICW are very narrow and would not be very safe to sail, certainly no room to tack if the winds were not perfectly favorable.
What is practical or not is an opinion, I hope we can agree on at least that. I do know that 50-80ft wide is enough room to tack and so for at least 90% what I have seen it is wide enough for tacking. The OP's boat might require more tacking space but surely not more than 150ft wide which is still most of the ICW.

For example, I tacked down adams creek last season because the wind was blowing directly against me there and it was at least twice as wide as it needed to be.

The rest of places you can wait for a wind that just isn't directly on the nose (upwind is ok) and this isn't really unlimited time, but could be a day or 2 at anchor perhaps.

A few times I arrived first because I sailed the outside while they motored the inside.
ICW isn't best if you are in a rush to get there.
Quote:

Further, it is not legal to sail through many of the opening bridges and I know of some that will not open until you drop your sails. Also not safe to sail under bridges, opening or fixed as the winds often change direction dramatically as it funnels under the bridge or is blocked altogether
Which bridge is illegal to sail through? This keeps being mentioned, but the actual "rule" is elusive. I would like to read it.

I have beat upwind under a number of opening bridges. The bridge structure greatly influences the wind. The operators are helpful and understand that I don't have power besides sail. I have never been refused a bridge opening and never been told afterwards not to do it again.

Saying that it is unsafe does not sound convincing when I have done this enough times and never found it to be a danger.

Can you justify why it is actually unsafe or are you posting this because you are uncomfortable by the idea that someone else could have an alternative style of navigation?

I suggest most competent cruisers will feel safe sailing in these situations especially if they have a reliable electric motor they can use at the flip of a switch unlike a diesel which might not start in time, so relying on it could lead to disappointment.
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