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Old 12-02-2012, 18:56   #46
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Re: Electrical propulsion vesus Diesel propulsion

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Or a genset capable of driving the motor directly thus giving you best of both worlds.
And back to what I'm saying, a DC diesel genset. What does a 20 Kw 120/240 generator weigh, I'm guessing 500+ lbs, whereas a 20 Kw DC gen set weighs 390 lbs.
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Old 12-02-2012, 19:30   #47
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Good point regarding sailing onto a reef in the old days. I think in a windless situation you would still be able to electric motor as long as your charge held out, then you could just hang out until you recharge.

Keep in mind I havnt pulled the old diesel or replaced it with electric yet. Still trying to decide and that's what makes these forums very valuable to learn from and toss around ideas. Thank you.

With an electric I can seal off two thru hulls.

I would like to hear more stories about using a diesel for extended amount of time. Running a diesel is only good as long as you have fuel. How long can you cruise until you run out of fuel? Someone posted about 400 miles. That's still a far cry from a major passage.

Also concerned about running during foul weather etc.
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Old 12-02-2012, 19:37   #48
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Re: Electrical propulsion vesus Diesel propulsion

Using a DC diesel gen set, your range is only limited by tankage.
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Old 12-02-2012, 19:40   #49
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Re: Electrical propulsion vesus Diesel propulsion

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Capt Mike,

So, if you are making a passage that you say to yourself "with these conditions I should average 7 kt" and you set motor speed for such, you could calculate an accurate ETA, and depending if you over or under estimated speed, you just arrive right on time with either a battery bank with more or less SOC?
Yes, I will use the motor if the wind starts to die and I want to make a certain speed to beat a current change or reach a destination. When I had my diesel I could move at about 5 knots max and it was a noisy five knots. With my Honda and battery charger I can move at 3 knots WITHOUT drawing any amps from my 10kw battery bank. But, here I'm limited by the 900 watts from my battery charger/power supply. One tank (gallon) on the Honda will last about 4-1/2 hours doing this. Since the Honda 2000 can put out about 1600 watts max I could add an additonal power supply to max out the Honda a get a little more boat speed but, I never felt I needed to do it. I use the battery in that case as a reserve. I could also step up to a Honda 3000 but, it is heavier and does not really fit on board my 30 footer like the 2000 does. Of course I could have also put in a marine diesel generator (which was my backup plan if the Honda 2000 did not work out) and have 5 kw to play with. But, then I'm back to having a diesel on board. Once you get use to the smell of clean in the boat and bilge it's hard to think about ever going back to diesel. Let alone the spare parts I use to carry. Then there was the antifreeze, distilled water, oil...
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Old 12-02-2012, 19:53   #50
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Re: Electrical propulsion vesus Diesel propulsion

Capt Mike,

Do you have the need for strong house power, like the typical 4000, surge to 8000 watt, 48VDC input inverter? Because the charge output can be selected, you could max out whatever portable gas generator your using, to the tune of 60 amps at 56.4 volts.
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Old 12-02-2012, 21:24   #51
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Re: Electrical propulsion vesus Diesel propulsion

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Capt Mike,

Do you have the need for strong house power, like the typical 4000, surge to 8000 watt, 48VDC input inverter? Because the charge output can be selected, you could max out whatever portable gas generator your using, to the tune of 60 amps at 56.4 volts.
Not sure I'm following. I have a separate 12 volt house bank and will on occassion use a 48 volt to 12 converter to run my laptop off off the 48 volt propulsion bank. Did this during Hurricane Earl since the 48 volt wind generator was really cranking. If you've know of something that could max out the Honda and provide 60 amps (way more than I need BTW) at 56 volts I'd like to know more. Though I think you may be talking about an inverter with 48 volts input and 120 volts output. Really have no need for that when the Honda is availible to provide 120 volts whenever I need it.
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Old 12-02-2012, 21:30   #52
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Re: Electrical propulsion versus Diesel propulsion

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And back to what I'm saying, a DC diesel genset. What does a 20 Kw 120/240 generator weigh, I'm guessing 500+ lbs, whereas a 20 Kw DC gen set weighs 390 lbs.
And what's the weight of the batteries, and the electric motors, and the inverter/charger/controls, and the fuel for the diesel gen?

My diesel puts out a rated 59 HP and weighs under 500 pounds (including reverse gear transmission). Add a starter battery (~60#) and 40 gallons of fuel (at ~7 pounds per gallon = ~280 pounds declining as it's used) and I can run at 85% throttle at 7+ knots into a 40 knot headwind for about 30 hours, longer at lower power. Total propulsion weight about 575-825# depending on fuel level.

Add your diesel/electric stuff up and I suspect it's probably double weight and double cost, takes more total space and is no less maintenance in the aggregate.
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Old 12-02-2012, 21:48   #53
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Re: Electrical propulsion vesus Diesel propulsion

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Originally Posted by Sovereigndreams View Post
Good point regarding sailing onto a reef in the old days. I think in a windless situation you would still be able to electric motor as long as your charge held out, then you could just hang out until you recharge.

Keep in mind I havnt pulled the old diesel or replaced it with electric yet. Still trying to decide and that's what makes these forums very valuable to learn from and toss around ideas. Thank you.

With an electric I can seal off two thru hulls.

I would like to hear more stories about using a diesel for extended amount of time. Running a diesel is only good as long as you have fuel. How long can you cruise until you run out of fuel? Someone posted about 400 miles. That's still a far cry from a major passage.

Also concerned about running during foul weather etc.

If you read the Bumfuzzles and blogs of others crusing the Pacific and other areas they do use their motors such that most carry extra fuel in jerricans and even then cruise between places they can refuel. (Most vessels are built for coastal crusing with inadequate tankage for extended crusing).

So yes being able to keep moving can be important in some crusing areas.

Sitting it out waiting for wind suits some but can also expose one to unwanted weather systems.

Being able to cruise under motor and avoid foul weather systems is an important safety factor certainly exposed by Steve Dashew in his fine series of 4 books in the Cruising Encycopedia which in my opinion are amongst the best of sailing Cruising references.

Cheers
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Old 12-02-2012, 21:56   #54
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Re: Electrical propulsion vesus Diesel propulsion

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Not sure I'm following. I have a separate 12 volt house bank and will on occassion use a 48 volt to 12 converter to run my laptop off off the 48 volt propulsion bank. Did this during Hurricane Earl since the 48 volt wind generator was really cranking. If you've know of something that could max out the Honda and provide 60 amps (way more than I need BTW) at 56 volts I'd like to know more. Though I think you may be talking about an inverter with 48 volts input and 120 volts output. Really have no need for that when the Honda is availible to provide 120 volts whenever I need it.
Yes, that is what I meant. The specs I gave were typical for a 4000 watt 48 volt input inverter. I plan on a fully electric galley and electric hot water so that size inverter is needed.
Magnum MS-4448PAE 48 VDC 4400-watt 48VDC to 120/240VAC sinewave Inverter

SailFastTri, the weight is a wash with my component selection plus I have flexibility as to where I place the weight which as you know on a light cat is important. The weight of your diesel is just for an engine, not a gen set. What is the typical weight for a 20Kw 120/240 gen set? A Westerbeke 22Kw is 829 lbs for 120/240 60 cycle, whereas a PolarDCmarine 20 Kw DC gen set tips the scales at 396 lbs. Don't you think that kind of weight savings alone justifies a DC diesel charger over a 120/240 60 cycle unit?

And to the followers of Steve Dashew, he was one of the first to promote a separate prop pitched astern on a dedicated shaft for charging under sail.
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Old 12-02-2012, 23:29   #55
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Re: Electrical propulsion vesus Diesel propulsion

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Hell, what a finincial hit that was.
Not a total loss. Torqueedo came good with a full refund. The E-pods were a write off though, so not a cheap excercise.

They still use the genset, they have a fully electric galley - ceramic cooktop, microwave/convection oven etc.

If the electric drives had proven to be more reliable, and a bit more powerful, it could have been pretty successful.
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Old 12-02-2012, 23:40   #56
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Re: Electrical propulsion vesus Diesel propulsion

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Not a total loss. Torqueedo came good with a full refund. The E-pods were a write off though, so not a cheap excercise.

They still use the genset, they have a fully electric galley - ceramic cooktop, microwave/convection oven etc.

If the electric drives had proven to be more reliable, and a bit more powerful, it could have been pretty successful.
When you say "ceramic cooktop" is that an element type of heat or induction? I'm planning on using induction.
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Old 12-02-2012, 23:59   #57
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Re: Electrical propulsion vesus Diesel propulsion

Don't think it's induction, the hotplate definitely gets hot. The cooktop is glass, and when you turn it on an element glows red under the glass.

Their entire galley is 240 volt - fridge/freezer, breadmaker, all the appliances. They have a big inverter too.

They have 48 volt lithium batteries, about 100 amp/hours I think, and a 5 kva 48 volt DC genset. Also a reasonable sized solar array and a wind gen, also in 48 volt.

The 12 volt system is run from one smallish AGM battery, kept charged from the 48 volt system by a DC-DC converter.

They run the genset every second or third day, only for maybe 3/4 hour, which keeps the batteries good. Lithiums are pretty much a must have for this set up to work well though. Lead batteries charge too slowly.
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Old 13-02-2012, 00:13   #58
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Re: Electrical propulsion vesus Diesel propulsion

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Don't think it's induction, the hotplate definitely gets hot. The cooktop is glass, and when you turn it on an element glows red under the glass.

Their entire galley is 240 volt - fridge/freezer, breadmaker, all the appliances. They have a big inverter too.

They have 48 volt lithium batteries, about 100 amp/hours I think, and a 5 kva 48 volt DC genset. Also a reasonable sized solar array and a wind gen, also in 48 volt.

The 12 volt system is run from one smallish AGM battery, kept charged from the 48 volt system by a DC-DC converter.

They run the genset every second or third day, only for maybe 3/4 hour, which keeps the batteries good. Lithiums are pretty much a must have for this set up to work well though. Lead batteries charge too slowly.
Thanks. Pretty much how I plan to do it, only real change is induction cook top.
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Old 13-02-2012, 04:38   #59
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Couldn't have said it better myself JRM. Your post about the death wish I misunderstood till reading your last post.

What happened to your last post?
After a re-read I decided it came off as way more mean-spirited than intended. This is one of those topics where people who have no clue about the subject love to share their ignorance.

Is diesel-electric hybrid more expensive than a straight diesel? Absolutely. Is it worth it? Absolutely. Is it silly that people with water makers, water heaters, microwaves, freezers, and washing machines shout it down as being expensive and unnecessarily complicated? Absolutely.

I'm quite happy with my electric boat, and so is anyone else who comes along for the ride. Yes, there are drawbacks. Certain death upon leaving the harbor isn't among them...

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Old 13-02-2012, 05:36   #60
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Re: Electrical propulsion vesus Diesel propulsion

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Not quite. An electric motor might have a cont rating of 5 hp, but will produced 30 hp for a thermal determined time frame. I built an electric scooter that does just that, so my small 0.77 Kw 48 volt battery bank will allow acceleration that beats my Corvette to 40 mph, and can cruise 6.5 miles. It fits into the dinghy quite nicely.


On a 8500 lb PDQ 36, where (2) 9.9 outboards do a fine job, two 4000 watt electrics will do at least as well. Modern lithium batteries would not be a weight penalty when the same 48 volt propulsion bank is also the house bank.

If it wasn't for me being the caregiver to my 92 year old dad, I would be showing all of you just how well this would work now. This whole debate feels like deja vue for me because I just went through all this on the engine I built for my hot rod. Everyone on the hot rod forum (except for a few) were telling me the only way to build an engine for performance was to accept that it will only return 5 mpg. My ride breaks 30 mpg, does a 10.8 @ 132 in the 1/4, and because I went to the extreme in mounting the engine and transmission as low in the frame rails as possible, it can pull 1.04G in the corners. It is my Swiss Army knife of hot rods. I always relish the challenge when popular belief says "it can't be done".

I just had to comment on this picture of what I assume is you and your Dad. If anyone looks closely they can see your Dad is not looking at the bike. Keep this one deckofficer, it's a picture worth a thousand words.
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