Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 12-02-2012, 11:54   #16
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by Sand crab View Post
I was hoping this thread would die but no, It's like a zombie, it lives forever! Actually, I like zombies. They are like my first ex, dead in bed.
On the torquedos and other inboard motors do they run backwards so you don't have to have a tranny? Likewise do they spin really slow?
Yes, all within the controller, so no gears. And 10 rpm if you want. The most efficient props are large and slow turning with a pitch that will allow your desired speed at the low rpm. The container ships I sailed on were diesel direct drive at a cruise speed set for 113 rpm. MacG, I know for the small scale of my future system, you would be onboard. I have no net weight gain over a conventional system.
__________________

__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 12-02-2012, 12:01   #17
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,005
Send a message via Yahoo to roverhi
Re: Electrical propulsion vesus Diesel propulsion

If a boat needs a 40hp diesel to power into a head sea and wind, it will need 40hp electric to do the same. Running an electric motor that large at full power will eat batteries so fast it will make your alternator spin. Electric power is fine for getting in and out of the slip and occasional short term light air powering with a small electric motor. For the real world of long distance cruising, electric power just doesn't work unless you carry a gen set. If you have to carry a gen set, why not just put in a diesel that will power the boat in all conditions and be done with it??
__________________

__________________
Peter O.
'Ae'a Pearson 35
roverhi is offline   Reply With Quote
Old 12-02-2012, 12:10   #18
Registered User

Join Date: Jan 2009
Location: Holland, France
Boat: 33ft sloop
Posts: 1,091
Images: 5
Re: Electrical propulsion vesus Diesel propulsion

For small craft that will be the only solution. But if your boat is a bit bigger, like Jedi' s Sundeer f.e., it may become a good idea.
__________________
MacG is offline   Reply With Quote
Old 12-02-2012, 12:14   #19
Registered User

Join Date: Sep 2011
Location: Germany
Boat: secondarily boatless
Posts: 178
Re: Electrical propulsion vesus Diesel propulsion

Guys,

let's do the math:

I have nice big batteries. 1000 Ah at 12 Volts = 12 kWh of Energy (out of which I probably never should draw more than 50%). This will run a 25 kW electrical engine for 30 minutes.

They weigh 480 kg or around 1,000 lbs. The equivalent in Diesel fuel is around 2 kg (10 kWh of thermal x efficiency).

The other option - a genset with electric motors - fares better, but still takes two conversions more: In the generator to electrical, and then in the motor again to mechanical. Net effect - less propulsion per liter of fuel. Couple that with the fact that this technology simply has not been refined to the same reliability as a diesel engine (admittedly, only hearsay on my part) and you have twice the trouble for half the fun.

...and did I mention that I love the redundancy of my two engines? Except when that redundant drive has brought me back to port - in there it is really virtually impossible to bring in the boat with just one engine...

Oliver
__________________
Oliver L. is offline   Reply With Quote
Old 12-02-2012, 12:25   #20
Registered User

Join Date: Nov 2008
Location: Bayfield, Lake Superior, WI
Boat: C&C 34
Posts: 358
Images: 1
Re: Electrical propulsion vesus Diesel propulsion

The real question here is whether you should carry a short-barreled shotgun or a 9mm with an extended mag on your diesel/electric genertor driven electric/non-electric day sailer cruiser?
__________________
Never, ever, ever take a sleeping pill and a laxative at the same time.
sailstoo is offline   Reply With Quote
Old 12-02-2012, 12:41   #21
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by Sand crab View Post
On the torquedos and other inboard motors do they run backwards so you don't have to have a tranny? Likewise do they spin really slow?

The torqueedo's have a planetary gearbox, so while the prop spins slowly, the actual motor spins pretty fast. About 10,000 rpm at full throttle I believe.
__________________
44'cruisingcat is offline   Reply With Quote
Old 12-02-2012, 13:25   #22
Registered User

Join Date: Feb 2012
Location: San Diego, CA
Boat: Cape George 36
Posts: 77
Images: 3
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by roverhi View Post
If a boat needs a 40hp diesel to power into a head sea and wind, it will need 40hp electric to do the same. Running an electric motor that large at full power will eat batteries so fast it will make your alternator spin. Electric power is fine for getting in and out of the slip and occasional short term light air powering with a small electric motor. For the real world of long distance cruising, electric power just doesn't work unless you carry a gen set. If you have to carry a gen set, why not just put in a diesel that will power the boat in all conditions and be done with it??
I don't understand why the assumption is always that the electric motor runs off of batteries. Perhaps, like the diesel electric ships and locomotives, it runs directly off of the genset.

Diesel engines have wonky power curves. They have narrow RPM ranges that produce optimal power. Outside that range and they're inefficient. Given the other power demands (electronic nav, lights, house power, etc)... lots of boats are running expensive giant diesel engines to charge house battery banks.

Should a compact diesel genset arise that can power a 40hp electric motor, it seems a no-brainer to replace the diesel with the a genset and motor. From what I've seen, most of these electric wonders will simply sit in the space that my gear/transmission box sits. They are about the same size. Now if I can replace the engine with a genset of the same size with adequate power output to run the motor, I don't really care about the battery capacity. Automating the genset to start up on demand based on load/battery capacity and adding an inverter and now I have AC house power, just like at the dock.

The problem is I haven't seen a genset with an output capacity that can physically fit into the space of my engine (and my engine is very space inefficient - VW Pathfinder marinized with a "kit" - looks very steam-punk compared to a modern Yanmar).
__________________
AuroraGH is offline   Reply With Quote
Old 12-02-2012, 13:34   #23
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by roverhi View Post
If a boat needs a 40hp diesel to power into a head sea and wind, it will need 40hp electric to do the same. Running an electric motor that large at full power will eat batteries so fast it will make your alternator spin. Electric power is fine for getting in and out of the slip and occasional short term light air powering with a small electric motor. For the real world of long distance cruising, electric power just doesn't work unless you carry a gen set. If you have to carry a gen set, why not just put in a diesel that will power the boat in all conditions and be done with it??

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".
__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 12-02-2012, 13:41   #24
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by AuroraGH View Post
I don't understand why the assumption is always that the electric motor runs off of batteries. Perhaps, like the diesel electric ships and locomotives, it runs directly off of the genset.

Diesel engines have wonky power curves. They have narrow RPM ranges that produce optimal power. Outside that range and they're inefficient. Given the other power demands (electronic nav, lights, house power, etc)... lots of boats are running expensive giant diesel engines to charge house battery banks.

Should a compact diesel genset arise that can power a 40hp electric motor, it seems a no-brainer to replace the diesel with the a genset and motor. From what I've seen, most of these electric wonders will simply sit in the space that my gear/transmission box sits. They are about the same size. Now if I can replace the engine with a genset of the same size with adequate power output to run the motor, I don't really care about the battery capacity. Automating the genset to start up on demand based on load/battery capacity and adding an inverter and now I have AC house power, just like at the dock.

The problem is I haven't seen a genset with an output capacity that can physically fit into the space of my engine (and my engine is very space inefficient - VW Pathfinder marinized with a "kit" - looks very steam-punk compared to a modern Yanmar).
They have just what you and I need. 5Kw through 50Kw at whatever charging voltages you need. Since we all run inverters, we don't need a heavy gen set for 120/240 60 hertz that has to run at some rpm /60.
http://www.propulsionmarine.com/wp-c...r-Brochure.pdf

Check out the weight (or lack there of) of these DC gen sets.
8 KW Polar DC Marine Generator | Propulsion Marine
__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 12-02-2012, 13:50   #25
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Electrical propulsion vesus Diesel propulsion

For you folks that have the big heavy boats up to 15 meters, this one will work just fine for your needs.....
http://www.propulsionmarine.com/wp-c...e-Brochure.pdf

User configurable for 8 different voltages (DC) from 48 volts @ 416 amps up to 320 volts @ 62.5 amps.
__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 12-02-2012, 13:50   #26
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by AuroraGH View Post
I don't understand why the assumption is always that the electric motor runs off of batteries. Perhaps, like the diesel electric ships and locomotives, it runs directly off of the genset.

Diesel engines have wonky power curves. They have narrow RPM ranges that produce optimal power. Outside that range and they're inefficient. Given the other power demands (electronic nav, lights, house power, etc)... lots of boats are running expensive giant diesel engines to charge house battery banks.

Should a compact diesel genset arise that can power a 40hp electric motor, it seems a no-brainer to replace the diesel with the a genset and motor. From what I've seen, most of these electric wonders will simply sit in the space that my gear/transmission box sits. They are about the same size. Now if I can replace the engine with a genset of the same size with adequate power output to run the motor, I don't really care about the battery capacity. Automating the genset to start up on demand based on load/battery capacity and adding an inverter and now I have AC house power, just like at the dock.

The problem is I haven't seen a genset with an output capacity that can physically fit into the space of my engine (and my engine is very space inefficient - VW Pathfinder marinized with a "kit" - looks very steam-punk compared to a modern Yanmar).
To power your 40 hp electric motor you'd need a bigger than 40 hp genset.

But the OP did mention refuelling with a power cord, which does suggest running off batteries...

While diesel torque curves may be "wonky" they work quite well in boats, where they can be set up to run in their most efficient rev range almost all the time. IC engines are pretty well suited to displacement boats. Much more so than to cars, which is why cars need multi-ratio gearboxes.
__________________
44'cruisingcat is offline   Reply With Quote
Old 12-02-2012, 14:09   #27
Registered User
 
deckofficer's Avatar

Join Date: Feb 2011
Location: Northern and Southern California
Boat: too many
Posts: 4,198
Images: 4
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by 44'cruisingcat View Post
Much more so than to cars, which is why cars need multi-ratio gearboxes.
Now that is a whole new subject, IMHO cars need to be electric. I have a stake bed truck I converted to electric and bought a container full of a China knock offs of the Smart Car, fully electric. When I'm at my place in SoCal, that is all I drive. Since I have a solar charged large bank of batteries for power outages, I just charge these two vehicles from that so the solar charge controller never has to back off the charge rate. Free driving except for insurance and windshield wiper fluid.
__________________
Bob
USCG Unlimited Tonnage Open Ocean (CMA)
http://tbuckets.lefora.com/
deckofficer is offline   Reply With Quote
Old 12-02-2012, 14:43   #28
cruiser

Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by deckofficer View Post
....
On a 8500 lb PDQ 36, where (2) 9.9 outboards do a fine job,....
Wait.... who told you this? Those motors are perfect for no winds and no waves, getting to and from the dock. For cruising, PDQ made the same boat as a LRC with twin diesels. Those 9.9's can't maintain boat speed into any kind of a head wind. Anyone who has them should tell you this.

Look, you've already made up your mind. I'm not going to wade in here. Let me just say that this is a great idea that just is not ready for prime time.

Remember, when you're out 'there' and the weather kicks up and things go bad...they go bad real fast and all at once. You need motors you can depend on for more than 30 minutes or you endanger your boat and crew.
__________________
Tropic Cat is offline   Reply With Quote
Old 12-02-2012, 15:24   #29
Registered User

Join Date: Sep 2009
Location: Mackay,QLD, Australia
Boat: planning a approx 45ft cat
Posts: 3,651
Images: 3
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by deckofficer View Post
MacG, my dear friend, I beg to differ. I have finally settled on which boat will be my final and last boat, and that is the little PDQ 36. I'll sell those two 9.9's and replace them with two Torqeedo 4.0's. For power generation, should I need to motor more than the 50 miles the 48 volt battery bank can take me, instead of a heavy, 120/240 60 hertz diesel genset, I'll use a diesel gen set that can run any rpm because it's output will be only DC at the charging voltage for the propulsion/house bank of batteries. 48 volt inverters if you have heavy 120 volt, 60 cycle loads are the best way to go because when you turn on that 1200 watt appliance, instead of 100 amps on the DC side, it is only 25 amps. I'll admit, both the DC genset and electric outboards are more expensive (but a lot lighter) than conventional. I will enjoy quiet motoring with gobs of torque and a fully electric galley all the way down to my 1500 watt electric BBQ on the railing, and pulling all the propane tanks, lines, regulators, alarms, and appliances out of the boat.

Very doable and not that expensive.
Deck Officer I wish you well In your future conversion.

However, it is fair to say that you are at the cutting edge of the technology with your bike and car conversions and I think the Torguedos you are talking about are only about to hit the marketplace not yet proven in the application.

There was a similar weight vessel in Australia (Oram) that went in the water with Torquedos and I think they gave up and went down another route. Others know more about this vessel than I.

Unfortunately at present the implementation of electric propulsion systems on crusing vessels for long distance crusing is still at the cutting edge of development and not yet mature technology nor yet price competetive.

If you are prepared to pioneer technology and accept all that comes with it that is your choice.

It is simply pushing the envelope at present to widely recomend electric drive systems for cruisers, generally.

cheers
__________________
downunder is offline   Reply With Quote
Old 12-02-2012, 15:39   #30
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Electrical propulsion vesus Diesel propulsion

Quote:
Originally Posted by downunder View Post
Deck Officer I wish you well In your future conversion.

However, it is fair to say that you are at the cutting edge of the technology with your bike and car conversions and I think the Torguedos you are talking about are only about to hit the marketplace not yet proven in the application.

There was a similar weight vessel in Australia (Oram) that went in the water with Torquedos and I think they gave up and went down another route. Others know more about this vessel than I.


cheers
Actually that boat was launched with E-power pods. They proved to be very poorly made and totally lacking in customer support, so were quickly replaced with Torqueedo's.

Unfortunately the Torqueedo's had several reliability issues also, and were replaced several times under warranty, until finally being replaced permanently by outboard power.
__________________

__________________
44'cruisingcat is offline   Reply With Quote
Reply

Tags
diesel, electrical, propulsion

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Gas Station Diesel vs Marine Diesel Rocketman Engines and Propulsion Systems 75 08-05-2016 20:31
Boat Diesel vs Truck Diesel In Training Engines and Propulsion Systems 37 26-11-2011 05:40
Pleased with Electric Propulsion boat_alexandra Engines and Propulsion Systems 34 11-11-2011 00:42
Do Not Use Biocide Journeyman Engines and Propulsion Systems 37 24-07-2011 19:47



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 22:25.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.