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Hi Rock,
As it so happens, we’re currently in the middle of our electric conversion on Revery. Also, Dan K converted his and Ewan (site admin) is converting using the same system I have. I’ll be starting a topic detailing everything in about a week, but I’ll be happy to answer any questions you might have.
I will leave you with this thought. For us, who will be long distance cruising, electric would NOT have made sense if we didn’t already have an 8kW generator “just lying around”. Battery technology is just not there yet to support the kind of range we need (IMO), unless you want to spend $25K+ on LiFePo4 batteries.
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I’m puzzled about these electric conversions. I suppose that it might work if your demands are very modest, say pulling in and out of your slip and maybe a bit of motoring to get out of the channel. The storage technology just isn’t there for cruising however. Let’s assume that you don’t care about powering into a headwind with chop for more than a few minutes. You’d like the ability to power in relatively calm seas and light winds for just 4 hours at only 5kts. An engine producing the equivalent of perhaps 15 hp would probably work. That’s about 11kw. With only batteries, you’d need about 1000 Amp hours at 12v. You can’t totally discharge your battery bank without damaging it. You could perhaps install 15 pairs of golf-cart batteries. I have no idea where you’d find the room, but let’s ignore that. The number of batteries doesn’t change if you change the voltage.
OK, so you want to put in a generator so you can extend your range. You’d need an 11kw generator and a charging system appropriate to your system. This only gets you minimal power. 5kw won’t do it. There’s some loss in the system so you’d probably need a 15kw generator.
It’s now 10 years later. Your needs have changed and you find that it’s time to sell your boat. For some odd reason, nobody wants to even look at your boat.
For long-distance cruising, the only way this makes sense is to put in a beefy 40kw diesel generator and an electric motor in place of the V-drive. I looked at that solution about 10 years ago when I repowered but there was no solution.
Torqeedo has something new on the market that has promise. The 40hp unit might work on the 424. I found a reference to price in the $100k range for the engine and battery bank.
https://www.torqeedo.com/us/en-us/products/inboardsRich
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just a fyi, my neighbor has put over 12 k in electric power plant in his pearson , vedus batterys ect,
just so you know , he hasent been able to leave the peir and when he did , the wind dies so does he, he can get 5 miles and then hes out of power, and no generator back up defeet the non use of fossel fuels.
somthing to think about -
All,
I highly recommend spending time with your electric system vendor, discussing your objectives.
Additionally, based on a couple of intrepid, real-world exemplars, you can apparently get quite far on used EV batteries. Your mileage may vary and this is definitely not an endorsement.
I plan on using those things called sails quite a bit 🙂 so motor sailing, and carrying a small generator to help with recharging in an emergency.
Will I make it through every weather condition no problem? No. But thats why I intend to cruise – no deadlines and I can pick my weather window. If I wanted to make it through every weather condition with my motor running, I’d buy a trawler, and not a 424.
Ewan
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Revery is now electric powered. I’ve been traveling way too much to do a proper write up yet, but here are a few observations. To set this up, we are preparing for a long term, long distance cruise, NOT coastal. Dan Kalinowski installed one for coastal, so if he chimes in, his installation and results will match his particular use. So here goes.
1. We cannot use electric without generator backup. 8kw is PLENTY for our 20kw system and we can get unlimited range at hull speed with it, as long as we have diesel.
2. 20kw at 48 VDC will drive us at hull speed into wind and chop if needed.
3. 20kw of TPPL telecom batteries plus the propulsion system was almost the exact weight of engine, tank, fuel, and vdrive. 65 lbs lighter to be exact. Generator, small tank, and fuel then added less than 500 lbs. We added weight up front to mostly offset that.
4. Motors fit where the vdrive was VERY well and the controllers can be put anywhere you want within about 6 feet of the motors (or more).
5. The system is designed to regenerate while sailing (think hydro generator) and drag / amps in is adjustable on the fly.
6. We’ll be adding ~1.2kw of solar to supplement charging…reducing generator time. It helps but doesn’t completely replace the generator.
7. Total cost including solar and all wiring/breakers/etc., minus generator was ~$17k but that includes the expendables (batteries), which is analogous to 5-7 years of diesel for our old W58 (usage, not price). Make sure you’re comparing apples to apples, folks!
8. Had we not gotten a stellar deal on a great used generator, we would have bought a Beta Marine engine instead. That is the long pole in the tent.
9. I did ALL the work, solo, in 4.5 weeks. Removal of engine, tank, and all the associated junk. Cleaning and bilge painting. Electric installation and battery box. NOT tidied up, as I did that in the slip to minimize yard time.
So this IS doable and won’t break the bank. A new Beta would have been ~$14.5k without associated junk needed to install it.
YMMV and I’ll try to start a post soon detailing everything. Is this for everyone? No. But it will serve us well.
Btw, Rich, no one wants to buy our boats anyway, just look at the market. LOL (I jest…a bit)
Evan
Revery #2191 user thanked author for this post.
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I’m reluctant to call your baby ugly, but this doesn’t work out on paper. Before anyone else out there runs out and spends well north of 10K for an electric power-plant, do the math. There’s about 750W/hp. A 20kw electric motor provides 26hp to the shaft. It doesn’t lose any power for accessories, transmission, or V-drive so it may be equivalent to a 40hp engine. What is the performance of a 424 with a 40hp engine? I’d be surprised if it’s hull speed into wind and chop, but let’s say it is. That’s what you’d have if you have at least a 20kw generator to drive it and a charging system that can handle the load. Anything less, and you’re drawing from your batteries. You don’t list the size of your battery bank. I’m pretty sure your batteries aren’t big enough to help for more than a few minutes. Unless your charging system provides enough power to drive the electric motor all by itself, I don’t see how this works for more than getting in and our of your harbor.
If I’m wrong in my calculations, I’d be the first to apologize. Let us know how this performs on a passage.
Rich
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Rich, your post gets to the heart of what I’m wondering – How do you drive a 20kw motor with an 8kw genny without dipping into your batts? Evan, are you achieving hull speed without running the motor at full power?
Attached here are the kw/speed/range charts I received from Oceanvolt in their quote for my 424 which was also for a 20kw motor.
Ryan
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I think the electric motors appeals to people with specific needs and expectations, that many of the rest of us do not share.
For exmaple, about 8 years ago I spent of few days in a berth next to a Canadian couple who had converted their Nonsuch (32?, I don’t remember the size) to electric. They did not have a generator and relied on solar and shore power keep their batteries charged. They spent every night in a marina. This was in Oriental, NC and they were on their way down the AICW. They said they averaged about 3.5 kts underway on AICW, about 1/2 the speed at which I would cruise. And they loved it! And they had made it that far from Missassaugua. So it worked for them. It would have driven me nuts!John
P.S> Thanks for the alert on the email response issue. I thought the site had gone totally non-functional. I will post a contribution now that I know how it works.
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All,
Mea culpa…I need to walk back one statement. That’s what happens when I try to hurry and also type on my phone. It’s also why I’m reluctant to discuss all if this due to the potential of it becoming a pissing contest. Remember, you’re free to believe and do whatever you want. It’s your boat. Cheers.What I intended to say is “unlimited range at cruising speed”. Rich and Ryan are correct that an 8kw generator will not run a 20kw system indefinitely. Physics is a bitch about things like that. lol
However, hull speed doesn’t require 20kw (sorry, Rich but you literally cannot do a simple apples to apples comparison using shaft HP, there are too many other variables. That and I’d like to know the efficiency of a 50-60 HP diesel when producing 40 shaft HP…if it even can). But I’m game to agree to disagree.Its a new system and I don’t have all the real world data points yet. But I’ll try to discuss the theoretical data as I’m able. So far, I know hull speed (or damn close) doesn’t require 20kw.
Also, Ewan is spot on in that you have to adjust your expectations. I sail. And I’m confident that the system can be depended on to keep me out of trouble, albeit as a HYBRID solution.
Ewan, it is the EY20… modified based in what they designed for you. Thanks!Evan
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Sometimes cruising is more than just waiting for the right wind to sail ( and from the right direction).
The need to move your boat from adverse conditions…. high winds, storms etc, necessitate a reliable power source not just for speed and power but for distance.
I can think of a many timesI was glad I had such a source in the Caribbean and Bahamas.
Waiting for batteries to charge or an under powered boat would have had severe consequences.Just my 2 cents
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It’s not just the generator that must be properly sized, you have to convert the generator output to run the drive motor, probably 48VDC. I’ve been scratching my head over this and can’t think of a cost-effective way to do this at the power rating needed. I’m interested to hear how this operates on a long run like a few hours. If there is some magic there that converts the full 8KW generator output for drive to the motor, you’d have 11 hp. My guess is that you get much less than this, half that or less. Whomever sold this package must have provided specs on the drive system. What do they say about power output with just an AC generator driving it?
This is all very exciting. It would be great to replace the engine on my 424 with a diesel electric solution that generates household power for things like air-conditioning. In theory, we should be able to replace our transmissions with an AC generator and our V-Drives with an electric motor. I’m a bit dubious however since I haven’t seen such a solution that makes sense on paper for less than $100K.
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Rich,
I think the best way to go is to use a 48v DC generator so no conversion needs to take place to power the motor. Then house AC loads are run off the inverter. This at least takes AC to DC conversion out of the equation.
My oceanvolt quote recommended this 11kw 48v DC genny: https://www.fischerpanda.de/Generator-Datasheet-AGT-DC_11000-48V_PMS-48_DC_-_400_Hz_112.htm
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I thought of that. You wouldn’t have the generator available for house needs like air conditioning or making pop-corn in the microwave with a DC generator. You could have something similar with a step-down transformer to 48VAC and a rectifier. Parts for this are not expensive. This would be a dirty and unregulated source of power however. There must be some electronics to control drive to the motor. It may not be happy with this kind of unregulated power supply. Other power converters may be prohibitively expensive.
Specs on the engine linked above are missing information. It doesn’t show maximum output or line regulation. It’s a 20kw Kubota, so one would think that max power output would be less than this. What happens if the drive system tries to consume more than the rated generator output? Does a breaker pop? That would be annoying, coming into a dock and give it a good goose of reverse thrust to stop the boat, Pop!
I think we’re starting to beat a dead-horse here.
Rich
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