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Tayana42 · 09-07-2021, 14:39

But, on a boat you do go up and down a lot. It shouldn’t be a great leap to harness that as an added energy recovery.

Celestialsailor · 09-07-2021, 15:40

Quote:

Originally Posted by Tayana42

But, on a boat you do go up and down a lot. It shouldn’t be a great leap to harness that as an added energy recovery.

I agree...Like I said...as technology progresses, there will be a way.

CaptWho · 10-07-2021, 02:37

Quote:

Originally Posted by Don C L

Yeah but the physics seems to favor just sticking with diesel for now, no? Given that diesels are run at a constant RPM anyway I don't see how running a diesel to generate electricity to power a prop will be more efficient.

Just consider that the diesel generator is a backup and you only run it when you need that extra power that your battery bank won't supply. You can get a 12v 300ah lithium battery now for less than $600. You can have a lot of power at your fingertips for a lot less than it cost last year. A 400w solar panel goes for less than $200. Sure, you run your diesel at a constant RPM, but is that RPM the most efficient setting for the engine given the speed that you want to achieve? With a genset, you set the engine up and run it at it's most efficient speed and you're still getting power from the panels, a wind generator (if you have it), and maybe regen from the prop if you're sailing.

laird · 10-07-2021, 10:16

Quote:

Originally Posted by CaptWho

Just consider that the diesel generator is a backup and you only run it when you need that extra power that your battery bank won't supply. You can get a 12v 300ah lithium battery now for less than $600. You can have a lot of power at your fingertips for a lot less than it cost last year. A 400w solar panel goes for less than $200. Sure, you run your diesel at a constant RPM, but is that RPM the most efficient setting for the engine given the speed that you want to achieve? With a genset, you set the engine up and run it at it's most efficient speed and you're still getting power from the panels, a wind generator (if you have it), and maybe regen from the prop if you're sailing.

The only problem I see with solar panels is that those of us in more northern countries ,those closer to the arctic ,will have to stick with diesel ,unless they can come up.With some new kind of super fuel

CaptWho · 10-07-2021, 15:09

Quote:

Originally Posted by laird

The only problem I see with solar panels is that those of us in more northern countries ,those closer to the arctic ,will have to stick with diesel ,unless they can come up.With some new kind of super fuel

Personally, I'd like to get maybe 7 of those 400w panels (variable depending on space) and a wind generator which should generate a little less than 3000w under ideal conditions. My plan is to stick more to the tropics.
I've been watching a YouTube channel called "Sailing Uma" and they're currently North of the Arctic Circle with their fully electric boat. They do not have a genset. They're getting by with their solar panels while stopping for an occasional charge at a dock somewhere and they have a lot less solar capacity than I'm planning on getting. From that data, electric would still be feasible if you lived up North.
You might have to run the genset a bit more, but you'd still have a lot less dependence on the fuel dock. I don't know if you're planning on cruising or if you're more of a day and weekend sailor. If you are the later, then you probably get back to the dock a lot and you could just plug it in and not have to worry about running out of battery while running the genset a bit more. I would also guess that if you're cruising, you're going to eventually end up in the tropics at some point.

Diogo Cyrineu · 11-07-2021, 16:10

Quote:

Originally Posted by CaptWho

1983 Jeanneau Sun Fizz 40' with Electric Engine OBO - $29,900 (Channel Islands, CA)

https://ventura.craigslist.org/boa/d...348136782.html

Very nice, just the new motor its 1/3 of the price.

Diogo Cyrineu · 11-07-2021, 21:43

Quote:

Originally Posted by CaptWho

1983 Jeanneau Sun Fizz 40' with Electric Engine OBO - $29,900 (Channel Islands, CA)

https://ventura.craigslist.org/boa/d...348136782.html

Very nice, Im looking for a boat without a motor to go electric. This one is already with a good motor. Just not ready to travel yet.

New LiFePo large bank would be nice in this boat.

Katapult Mike · 11-07-2021, 22:24

Quote:

Originally Posted by Don C L

I suspect that in this case the electric motor may be a liability; I wonder how long it can realistically go on those batteries. It may be one of the reasons for the lower price.

I like that Choate though!

Batteries are getting better and cheaper every year, so if you upgrade in a couple years it might not be that bad. There are a lot of old boats with solid hulls and bum motors that could get a new lease on life.

Man, what a dream, a sailboat with no diesel and no diesel fumes.

mitiempo · 11-07-2021, 22:44

Quote:

Originally Posted by Katapult Mike

Batteries are getting better and cheaper every year, so if you upgrade in a couple years it might not be that bad. There are a lot of old boats with solid hulls and bum motors that could get a new lease on life.

Man, what a dream, a sailboat with no diesel and no diesel fumes.

It's not the batteries but the charging that is the larger problem. For a day sailor back at the dock to plug in it can work well. Cruising away from shore power not so much.

Chili Palmer · 12-07-2021, 14:49

Quote:

Originally Posted by CaptWho

1983 Jeanneau Sun Fizz 40' with Electric Engine OBO - $29,900 (Channel Islands, CA)

https://ventura.craigslist.org/boa/d...348136782.html

I'm a fan of new technology and would absolutely have an electric motor on a boat but, I think that motor is slightly undersized for the boat. Their page says it's good for 40' boats but 20HP isn't a lot. Yes, I'm aware electric motors provide all of their power from zero RPM.

marcjsmith · 12-07-2021, 15:35

Quote:

Originally Posted by Don C L

I know this has come up before, but I'd really need to see the math on that. Sounds kinda Rube Goldberg to me.

Don’t have the maths, but trains and larger boats run in diesel/electric power plants. Ie. The Diesel engine just spins a generator which then send power to the electric motors... in a large boat, like a cruise ship, they aren’t concerned about the excess electrons. Plenty of power hungry appliances board.

I think it would neat to go with an electric setup. But range anxiety would always be on my mind...

CaptWho · 13-07-2021, 03:32

Quote:

Originally Posted by Chili Palmer

I'm a fan of new technology and would absolutely have an electric motor on a boat but, I think that motor is slightly undersized for the boat. Their page says it's good for 40' boats but 20HP isn't a lot. Yes, I'm aware electric motors provide all of their power from zero RPM.

Electric motors deliver more power per HP, so the 20HP electric might be comparable to somewhere in the neighborhood of a 50HP diesel. https://electricyacht.com/design-and.../motor-sizing/

Chili Palmer · 13-07-2021, 10:30

Quote:

Originally Posted by CaptWho

Electric motors deliver more power per HP, so the 20HP electric might be comparable to somewhere in the neighborhood of a 50HP diesel. https://electricyacht.com/design-and.../motor-sizing/

Yep, I'm aware of that, however, even if the 20HP e-motor puts 40HP to the prop I still feel like that boat is underpowered.

To check if I'm just being delusional I poked around and it seems like most boats of this size/age have a minimum of 40HP. I found 47, 50, and even 60 HP motors in this size of boat.

The link you provided discusses the loss through transmission, etc. In the car world that percentage of loss can vary from 15 to 25 %. If the 40HP is reduced by 25% you're looking at 30HP.

I thought I was underrating the torque of the e-motor as that's what gets things moving so took a look at that.

This link shows a Westerbeke 40 with torque ranges from 60-80

https://www.westerbeke.com/advanced%20specs/w40.pdf

This link for e-motors in general shows a at 20HP it has around 60 lb ft of torque, so definitely within range, but also maybe on the low end. EDIT: this is only a reference and I can't confirm the data or how it relates to the motor in question.

https://www.engineeringtoolbox.com/e...pm-d_1503.html

And last but not least, the link they provided in the ad (below) states the recommended HP swap range of 15-25 HP.

https://www.emarineinc.com/Elco-EP-2...Electric-Motor

To summarize, it seems like a 20HP e-motor MAY be able to push this boat but that's going to be at the upper limits of that motor (which is not good) and given the e-motor manufacturers recommendations for HP swap ratings this boat is in fact underpowered if it originally came with a 40+ HP motor.