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Old 02-02-2016, 14:41   #16
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

The technical limitations of electric propulsion are exaggerated. Back in 2007, the 14m solar-electric catamaran Sun21 crossed the Atlantic from the Canaries to St. Martin in 29 days, using no sails and no combustible fuels, averaging about 5 knots. That was using two tonnes of lead-acid batteries, not LiFePO4. Today, about 1.5 tonnes could be saved by using LiFePO4 batteries. More efficient solar panels are available now too.

With diesel, range is limited by how much fuel one can carry. With solar-electric, range is unlimited. However, as I wrote earlier, most cruisers will not be willing to make the compromises/sacrifices needed to install the solar and battery capacity needed to cover long distances with electric propulsion. 50-100 miles is about as far as a typical, reasonable electric propulsion sailboat is going to go electric-only. About 1000W of solar is going to provide about enough daily range on passage to overcome currents i.e. to not be adrift.

So, for day sailors, electric propulsion should be fine. For passage making, it would be very difficult to make electric propulsion as convenient as diesel.
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Old 02-02-2016, 15:03   #17
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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The technical limitations of electric propulsion are exaggerated. Back in 2007, the 14m solar-electric catamaran Sun21 crossed the Atlantic from the Canaries to St. Martin in 29 days, using no sails and no combustible fuels, averaging about 5 knots. That was using two tonnes of lead-acid batteries, not LiFePO4. Today, about 1.5 tonnes could be saved by using LiFePO4 batteries. More efficient solar panels are available now too.
Didn't that boat cost something like 15 million dollars?
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Old 02-02-2016, 15:20   #18
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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Didn't that boat cost something like 15 million dollars?
No, that was Turanor, an 85 tonne floating palace, which in 2013 crossed the Atlantic in 22 days. I don't know the cost of Sun21, which at 12 tonnes is fairly spartan, but my estimate is very roughly about $1 million.
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Old 02-02-2016, 15:37   #19
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

Go diesel and go sailing.
Most of the major marinas around here have one or two electric drives...in the back, under a tarp, collecting dust. I think the time will come when they are sensible on a cruising boat but for the large part it ain't today.
That being said, I took my first ride in a Tesla the other night...HOLY KEERAP! I want one...Badly.

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Old 02-02-2016, 16:03   #20
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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The technical limitations of electric propulsion are exaggerated. Back in 2007, the 14m solar-electric catamaran Sun21 crossed the Atlantic from the Canaries to St. Martin in 29 days, using no sails and no combustible fuels, averaging about 5 knots. That was using two tonnes of lead-acid batteries, not LiFePO4. Today, about 1.5 tonnes could be saved by using LiFePO4 batteries. More efficient solar panels are available now too.
10kW of solar panels occupying 65 m2, 50kWh of battery storage and just 2 x 8kW motors.

And a downwind passage. Let's see then do it the other way


Technically feasible? Yes. Practical for a cruiser? Not there yet!
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Old 02-02-2016, 16:07   #21
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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Most of the major marinas around here have one or two electric drives...in the back, under a tarp, collecting dust.
I've also seen some of those, all of which had lead-acid batteries. A few people have electric propulsion supported by lead-acid batteries and are satisfied but, in my opinion, electric propulsion requires at least LiFePO4 batteries.

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I think the time will come when they are sensible on a cruising boat but for the large part it ain't today.
Electric motors are already extremely efficient, so there are really only two significant opportunities to improve the technology for electric propulsion: batteries and photovoltaics. LiFePO4 are already dramatically better than any variant of lead-acid, by any metric: W/liter, Wh/liter, W/kg, Wh/kg, cycle life, simplicity of charging, life cycle cost, etc. However, in the future, Lithium-Silicon batteries will be a huge improvement over LiFePO4, most important, Lithium-Silicon batteries will outperform LiFePO4 batteries in terms of Wh/kg by a factor of at least three. There is not so much room for improvement in photovoltaics. Currently, the best PV panels (that don't have to be aimed directly at the sun) are about 22% efficient. I guess that might improve to somewhere between 25% and 30% over the next 20 years.

I think electric propulsion for sailboats using LiFePO4 batteries is already fine for day sailing, is tolerable for some people for short passages, e.g. Caribbean or Mediterranean, and is seriously problematic for ocean crossings. Lithium-Silicon batteries will, in my estimation, make electric superior to diesel for short passages such as around the Caribbean or within the Mediterranean. Even with Lithium-Silicon batteries and hypothetical 30% efficient solar panels, crossing oceans with electric propulsion will involve serious compromises that are not for everyone. Maybe someday Lithium-Air batteries will make it from the labs to practical for use on boats, but my guess is practical Lithium-Air batteries are at least 20 years away, if ever.

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I took my first ride in a Tesla the other night...HOLY KEERAP! I want one...Badly.
I made the switch to electric cars and would absolutely never go back to internal combustion. However, what I think will be the main driver of electric car adoption does not apply to boats. Most parents find it nearly impossible to get a teenager to return a car with a full tank, however, electric car owners have little problem getting teenagers to plug in when they return home. Won't work for boats.

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10kW of solar panels occupying 65 m2, 50kWh of battery storage and just 2 x 8kW motors.

And a downwind passage. Let's see then do it the other way


Technically feasible? Yes. Practical for a cruiser? Not there yet!
That was 2007, using lead-acid batteries. I certainly agree that even with LiFePO4 batteries, solar-electric propulsion without sails is not yet practical for ocean crossings. Even with sails, solar-electric propulsion for ocean crossings requires compromises that are not tolerable for most sailors. Day sailing and short passages are another story.
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Old 02-02-2016, 18:05   #22
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

I salvaged 2 old electric pallet jacks for $200 each. With their motors and controllers i saved a bundle and instead of a huge battery bank im building a genset to run from my teather rather then the boat. This mainly was to open up the floor and get that old perkins and fuel tanks out so i had more walking space. Diesel is just SO powerful it cant be ignored so im trying both worlds to see how it goes. I suspect the resale on an electric is **** but it will be quiet inside and have some range. Pairs of 24 volt batteries run up the center above the keel so as my wallet grows so can my battery banks.
Money isnt everything sometimes. Conside what a clean cedar interior is worth smelling instead of grease and diesel... Something to consider.
Happy sailing!
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Old 02-02-2016, 18:42   #23
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

Getting back to resale. If the battery problems are remedied then It was a good move on my part. I had a old MD2B volvo that was locked up from the previous owner. I wanted to replace but all I need is to get in and out of the marina. It's called sailing for a reason.
I someday want to sail the world and don't want all the smells, maintenance, mess, and problems of a diesel. I have seen to many videos in foreign lands about dirty or wet diesel fuel.
I was able on a full charge to run my electric motor for about 45 minutes.Sailing most of the move. I do believe though that I own a sail boat. So if I am 15 miles away from the dock and cannot make it back for monday morning then that is on me.Keep sailing through the night and learn from the mistake.
I am also looking for a generator and/or hybrid system to install if I have to. But for now I want solar and wind to tweek first.
I feel if I can get the range up to 5 miles that is all anyone will need as a typical coastal cruiser. Which I am not admittedly. But when the buyer sees (if I do sell my boat) he or she doesn't need to go to the fuel dock before leaving. That the solar panels topped off the batteries while he or she was at work. That is a plus and not a minus.
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Old 02-02-2016, 18:49   #24
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pirate Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

My guess is that for the next 5 years resell value would take a hit. After that ---who knows. ...perhaps electrics will fetch a premium! (lol)
I definitely think the future is electric....I could be wrong but thats where Im hanging my hat.
I recently converted to an electric 10 Kw system and could not be happier. The quiet, the lack of fumes, the surprising low draw at 3-4 knots, and the reliability are all big pluses for me. I expect my kids will take over the boat later on so I guess they will need to deal with the resale if they choose to sell.

While I think electric brushless motors are more reliable than diesels, the range anxiety issue is always forefront. However regenerative charging using the prop, + solar, CTOW and if needed, an onboard generator can do a lot to alleviate this issue.
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Old 02-02-2016, 19:55   #25
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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Originally Posted by StuM View Post
10kW of solar panels occupying 65 m2, 50kWh of battery storage and just 2 x 8kW motors.

And a downwind passage. Let's see then do it the other way


Technically feasible? Yes. Practical for a cruiser? Not there yet!
Agree. Just to translate the specs of Sun 21 into terms that relate to a cruiser.

65 sq mt (700 sq ft to us Americans) means you'll need cover a space roughly 6M X 11M (20' X 35') with solar panels. Not even feasible for most monohulls. Cost? 10 kW of panels even at today's lower prices will set you back a bar minimum 10,000, maybe double for top of the line panels.

2 X 8 kW motors is about 10 HP each. Not much for a 14M boat, even a catamaran. Like Stu said, might work downwind but try punching into a headwind or big chop with 20 HP.

Haven't even mentioned what you do if you have several days of cloudy weather. Even in the tropics I've seen total overcast for two weeks straight.

Unless one spends big money in a fancy, custom installation (which will include a large, expensive diesel genset)or only uses electric only to get from the dock to the channel it just isn't ready for prime time.
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Old 02-02-2016, 21:40   #26
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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The technical limitations of electric propulsion are exaggerated. Back in 2007, the 14m solar-electric catamaran Sun21 crossed the Atlantic from the Canaries to St. Martin in 29 days, using no sails and no combustible fuels, averaging about 5 knotsYour average diesel long range power vessel might run 20% faster on a crossing.. That was using two tonnes of lead-acid batteriesequivalent to 500 gal on hulls specifically designed for efficiency likely result in upwards of 3000-4000 miles range good for most crossings with diesel., not LiFePO4. Today, about 1.5 tonnes could be saved by using LiFePO4 batteries. More efficient solar panels are available now too.

With diesel, range is limited by how much fuel one can carry. With solar-electric, range is unlimitedUnless you get cloudy days or are in higher lat or you need to run at full power for more than an hour. However, as I wrote earlier, most cruisers will not be willing to make the compromises/sacrifices needed to install the solar and battery capacity needed to cover long distances with electric propulsion. 50-100 miles is about as far as a typical, reasonable electric propulsion sailboat is going to go electric-only.and even that is a high end system in ideal conditions. About 1000W of solar is going to provide about enough daily range on passage to overcome currents i.e. to not be adrift.

So, for day sailors, electric propulsion should be fine. For passage making, it would be very difficult to make electric propulsion as convenient as diesel.
The boat you speak of was specifically designed to prove a point. It was not built as a viable production cruiser.

There was a recent thread about 3 women rowing across the pacific. They aren't using a lot of diesel either but no one is suggesting its the next big thing in cruising.
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Old 02-02-2016, 22:09   #27
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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There was a recent thread about 3 women rowing across the pacific. They aren't using a lot of diesel either but no one is suggesting its the next big thing in cruising.
Rowing, schmowing. The next big thing will be kayaking.

Like cruising from Germany to Australia by kayak - retracing the route of Oskar Speck: Home Page

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Old 02-02-2016, 22:22   #28
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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My guess is that for the next 5 years resell value would take a hit. After that ---who knows. ...perhaps electrics will fetch a premium! (lol)
I definitely think the future is electric....I could be wrong but thats where Im hanging my hat.
I recently converted to an electric 10 Kw system and could not be happier. The quiet, the lack of fumes, the surprising low draw at 3-4 knots, and the reliability are all big pluses for me. I expect my kids will take over the boat later on so I guess they will need to deal with the resale if they choose to sell.

While I think electric brushless motors are more reliable than diesels, the range anxiety issue is always forefront. However regenerative charging using the prop, + solar, CTOW and if needed, an onboard generator can do a lot to alleviate this issue.
Please tell us more about your conversion. Why, cost, upside, downside. All others have opinions, but you have experience. it seems like you have all of the power backup options in place ...
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Old 02-02-2016, 22:53   #29
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

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Agree. Just to translate the specs of Sun 21 into terms that relate to a cruiser.

65 sq mt (700 sq ft to us Americans) means you'll need cover a space roughly 6M X 11M (20' X 35') with solar panels. Not even feasible for most monohulls. Cost? 10 kW of panels even at today's lower prices will set you back a bar minimum 10,000, maybe double for top of the line panels.

2 X 8 kW motors is about 10 HP each. Not much for a 14M boat, even a catamaran. Like Stu said, might work downwind but try punching into a headwind or big chop with 20 HP.
Sun21 is not a sailing vessel.

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Haven't even mentioned what you do if you have several days of cloudy weather. Even in the tropics I've seen total overcast for two weeks straight.
On overcast days, solar panels generate about half the electricity they generate on sunny days. So that would mean one could only go about 79% as fast, for the same period of time, covering only about 79% of the distance.
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Old 03-02-2016, 09:17   #30
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Re: Comparing diesel vrs electric propulsion(DIY/Production) in terms of resell value

2 X 8 kW motors is about 10 HP each. Not much for a 14M boat, even a catamaran. Like Stu said, might work downwind but try punching into a headwind or big chop with 20 HP.

I'm sorry but your looking at it wrong. Do not use horse power I initially made that mistake. Torque and instant torque is what you need. With electric you have it.
With hull design your not looking to get a sailboat on a plane. Your lucky to do 7 knots with a diesel going 2500 RPM downwind. The hull and boats just aren't built for more then that.
With that in mind it doesn't take a lot to get my contest 33 sailboat moving to 4 to 6 knots. And setting an anchor is not a problem either. I usually run half throttle but as I said I am not in a hurry. If I was I'd buy a completely different boat.
At the St Pete Boat show a few years ago was a pontoon specially built for touring. It had 4 solar panels on the roof and it was said to go all day long with just them. Now it wasn't going to break any sea speed records but they said it would do a few knots with the little motor it had.
By the way at 48 volts my electric motor is rated at 6 to 14 horse power. 14.7 horse power is peak power for only a minute or two. But the torque to turn the prop is what you have to watch out for. At 20 volts it is rated for 2000 rpm. I did drop it from 1 to 1 to 2 to 1 just to keep the stuffing box cool. Also a three bladed prop is a must.
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