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Old 08-08-2021, 07:56   #301
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Re: Replace Diesel with electric engine

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....Electric is great for those not going anywhere.
Spot on!!!
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Old 08-08-2021, 08:01   #302
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Re: Replace Diesel with electric engine

"... to think outside the box ..." - is easily confused with "re-inventing the wheel"
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Old 08-08-2021, 08:04   #303
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Re: Replace Diesel with electric engine

With current technology , no logical examination of the changeover to electric propulsion makes engineering or financial sense. From the few examples I’ve seen owners largely did it because of misplaced personal convictions , a sense of latest fashion tech , or more money then sense ( which is very prevalent in boat owning )
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Old 08-08-2021, 08:16   #304
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Re: Replace Diesel with electric engine

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Originally Posted by goboatingnow View Post
With current technology , no logical examination of the changeover to electric propulsion makes engineering or financial sense. From the few examples I’ve seen owners largely did it because of misplaced personal convictions , a sense of latest fashion tech , or more money then sense ( which is very prevalent in boat owning )
If you are extremely short on money, a DIY EP system makes a lot of sense. That's how Uma wound up with an electric drive. They could only afford to buy a boat with a busted motor. It was cheaper to DIY an EP system with a forklift motor than to fix or replace the diesel. I know they replaced that with an OceanVolt sail drive but before then they went across the Atlantic on the forklift motor if I recall.

There are no engineering impediments to having an EP system, just non-monetary tradeoffs to having it, for people willing to accept those tradeoffs it works. Just because it is not a decision you would make doesn't make it illogical.
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Old 08-08-2021, 08:29   #305
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Re: Replace Diesel with electric engine

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Originally Posted by Adelie View Post
If you are extremely short on money, a DIY EP system makes a lot of sense. That's how Uma wound up with an electric drive. They could only afford to buy a boat with a busted motor. It was cheaper to DIY an EP system with a forklift motor than to fix or replace the diesel. I know they replaced that with an OceanVolt sail drive but before then they went across the Atlantic on the forklift motor if I recall.

There are no engineering impediments to having an EP system, just non-monetary tradeoffs to having it, for people willing to accept those tradeoffs it works. Just because it is not a decision you would make doesn't make it illogical.
The idea of getting electric power on the cheap because a diesel costs too much is a trap. In the end there is either a huge loss of utility or a big cost. Uma changed when their financial situation changed. They wouldn't have gone to the Oceanvolt system if their existing system was satisfactory.
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Old 08-08-2021, 09:04   #306
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Re: Replace Diesel with electric engine

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The idea of getting electric power on the cheap because a diesel costs too much is a trap. In the end there is either a huge loss of utility or a big cost. Uma changed when their financial situation changed. They wouldn't have gone to the Oceanvolt system if their existing system was satisfactory.
if you put up with 2kn of speed in flat calms & 1/2h of running time it can be done!
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Old 08-08-2021, 09:52   #307
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Re: Replace Diesel with electric engine

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Originally Posted by wingssail View Post
The idea of getting electric power on the cheap because a diesel costs too much is a trap. In the end there is either a huge loss of utility or a big cost. Uma changed when their financial situation changed. They wouldn't have gone to the Oceanvolt system if their existing system was satisfactory.
Define satisfactory. They upgraded because the OV system was somewhat more energy efficient, possibly more powerful and because it came to them for FREE except for the cost of ancillary items, haulout, fiberglass and epoxy.

The existing system worked and met their needs. The new motor gives them slightly more range and some regen.
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Old 08-08-2021, 10:13   #308
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Re: Replace Diesel with electric engine

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if you put up with 2kn of speed in flat calms & 1/2h of running time it can be done!
2kt is less than 500W. Depending on panel capacity, battery size and house uses a boat might be able to motor 24/7 at that rate in flat calm.

1/2hr running time is only at hull speed for most EP boats.
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Old 08-08-2021, 10:17   #309
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Re: Replace Diesel with electric engine

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Originally Posted by Adelie View Post
Define satisfactory. They upgraded because the OV system was somewhat more energy efficient, possibly more powerful and because it came to them for FREE except for the cost of ancillary items, haulout, fiberglass and epoxy.

The existing system worked and met their needs. The new motor gives them slightly more range and some regen.

Adelie, You are absolutely right. But my point is that if they had to purchase the OV unit (and the ancillary items, and the cost of the haulout and installation) it would not have been a DIY EP system for someone extremely short on money. It would have cost them a substantial amount.

That is the "trap": It looks cheap but the needed ancillary equipment, the installation, and upgrades for desired power, range, and dubious regen, raises the cost.

A friend with a CT 41 described the realities of his electric drive system:

"It didn't cost much but it wasn't free, and you have to learn how to sail."

Actually, not bad, if you think about it.
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Old 08-08-2021, 10:32   #310
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by Adelie View Post
2kt is less than 500W. Depending on panel capacity, battery size and house uses a boat might be able to motor 24/7 at that rate in flat calm.

1/2hr running time is only at hull speed for most EP boats.
Adelie, I don't get your calculation here. Studentdriver is talking about a 48000lb 52' boat and you are saying it can go 2kts on less than 2/3 of one horsepower? (and who thinks 2kts is sufficient?)

And even then, using your 500watts for 24hours means 12kw, which is a lot to collect in solar in the normal 6 hours of full solar sunlight. However big a battery he has, eventually he has to replenish 12,000 watts per day.

I don't think this is practical for most cruisers.
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Old 08-08-2021, 10:54   #311
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Re: Replace Diesel with electric engine

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.
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Old 08-08-2021, 11:05   #312
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Re: Replace Diesel with electric engine

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I've found this boat, and the new owner (studentdriver) on Aluminum Anarchy, https://forums.sailinganarchy.com/in...minum-anarchy/

It is a beautiful and valuable boat. What it needs is some TLC, not the diesel/electric conversion he is contemplating.

Clean this boat up, get everything working, and he'll have a wonderful liveaboard and/or world cruiser.

But, install a big gen set, electric drive, and all the electrical bits to go with it, as well as removing vast amounts of what it there, unless done totally professionally will destroy the potential value of this boat. And if it is done totally professionally it will be a huge project and a huge cost.

Reconsider
Please enlighten the Germans - what is TLC meant.
Abbreviations are alwas complicate to us Germans (and maybe others?).
Many thx.
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Old 08-08-2021, 11:15   #313
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Re: Replace Diesel with electric engine

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Please enlighten the Germans - what is TLC meant.
Abbreviations are alwas complicate to us Germans (and maybe others?).
Many thx.
They mean tender loving care… i.e. it’s a project boat
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Old 08-08-2021, 11:39   #314
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Re: Replace Diesel with electric engine

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Originally Posted by s/v Jedi View Post
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.
On what basis do you think that 20hp will drive Jedi at 6kts? I'd guess that it will be 2-3 times that power required. For 6 kts, what RPM do you run your Yanmar at? The horsepower/rpm curve for that motor should tell you what it is putting out to get you that speed. I'd say that at 1800 RPM that would be about 48 hp, or 40kw. Well, whatever.

The point is that you'd need a 16kw gen set for 20hp, and a 50kw gen set for 60hp. Somewhere in that range would get you 6 kts. I don't see why it is "no question about it" why you'd replace one diesel with another AND the electrical drive equipment, etc. Why are you so sure about it?
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Old 08-08-2021, 11:58   #315
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Re: Replace Diesel with electric engine

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On what basis do you think that 20hp will drive Jedi at 6kts? I'd guess that it will be 2-3 times that power required. For 6 kts, what RPM do you run your Yanmar at? The horsepower/rpm curve for that motor should tell you what it is putting out to get you that speed. I'd say that at 1800 RPM that would be about 48 hp, or 40kw. Well, whatever.

The point is that you'd need a 16kw gen set for 20hp, and a 50kw gen set for 60hp. Somewhere in that range would get you 6 kts. I don't see why it is "no question about it" why you'd replace one diesel with another AND the electrical drive equipment, etc. Why are you so sure about it?
I base that on the calculator. 20hp = 15kW and I think it evenshows more speed than 6kts for me. At 40kW, your suggestion, my speed will be 8.5 kts.

I guess that explains it. In 99% of the time I would not need diesel at all, but if needed I can motor for days. Not sure yet what size genset would be optimal, wish I could get more resolution in this graph.
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