Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 23-04-2008, 05:53   #16
Registered User

Join Date: Aug 2007
Posts: 944
Hi hope that by the time I get a boat, I will be able to get really good and reliable electric motor by then. Hopefully, they would've perfected them enough to where they are truly a no brainer to operate and repair (if needed). I would also have solar panels as well as a wind generator to help keep my batteries tapped.

This may be my fantasy land idea but I hope I can get that much closer to that reality soon.
__________________

__________________
shadow is offline   Reply With Quote
Old 23-04-2008, 06:09   #17
Registered User

Join Date: Apr 2008
Location: Bristol UK
Boat: 1937 48ft wooden motor passenger vessel
Posts: 9
Hi shadow, been looking at this for a while now for my passenber boat. Go look at The Electric Boat Association (EBA) Massive amounts of info and really good links.

Good luck
Ade
__________________

__________________
adrian pye is offline   Reply With Quote
Old 23-04-2008, 06:12   #18
Registered User

Join Date: Nov 2005
Location: Ohio
Posts: 2,311
Quote:
Originally Posted by ess105 View Post
????????? = wind. It is a sailboat. If you want a motor boat, don't buy a hybrid. Doesn't make any sense whatsoever. However, while you're running on the primary source (wind) you get to run your electrics and top off your drive batteries for free. On long passage there is no need to burn any oil to power your fridge. You have enough power in the batteries to get on and off your hook.
But for $800 I can buy a Ferris water generator to tow behind the boat to power everything and not have the complexity of a hybrid. And a big diesel can rumble along for days when the breeze is no where to be found.

It will be interseting it see if the controllers have the robustness to survive the rigors of life aboard. The diesel/tranny has already been proven.
__________________
Joli is offline   Reply With Quote
Old 23-04-2008, 06:15   #19
Registered User

Join Date: Nov 2005
Location: Ohio
Posts: 2,311
Quote:
Originally Posted by Don Lucas View Post
Thanks for the responses. Lots of Pros/Cons items, some are of course are the resistance to change things. Hope we get some more responses from people who have real experience with this whole thing.

By the way, nuc subs shut down the reactors all the time. What do you think drives the boat when the reactor is down; a BIG batttery and electric motor coupled to the shaft. I don't think there is a problem here of the diesel/electric hybrid working great. I think the thing is a scale one of getting vendors etc to develop the idea down to the size we need. This of course is marketing 101 in that they won't if they feel it won't be accepted and pay back the investment.
A huge and heavy battery bank is just what the owner of a cat wants?
__________________
Joli is offline   Reply With Quote
Old 23-04-2008, 08:57   #20
Registered User
 
Beausoleil's Avatar

Join Date: Jul 2007
Location: Potomac Shores, VA USA
Boat: Formosa 51 Aft Cockpit Ketch - "Beausoleil"
Posts: 565
Images: 1
Quote:
Originally Posted by Don Lucas View Post
By the way, nuc subs shut down the reactors all the time. What do you think drives the boat when the reactor is down; a BIG batttery and electric motor coupled to the shaft.
Don,

Just a technical nit: While I'm not a nuclear engineer, I'm pretty sure that nuclear subs do not "shut down the reactors all the time". It's a pretty serious process to fully shutdown a nuclear reactor. They may take them off-line - reducing the power output by fully inserting all the control rods. And yes, they probably do run on battery when doing emergency service on the engine/reactor plant. Any "scheduled" maintenance would be while in port or drydock, even.

Back to diesel-electric: I think it's pretty obvious that once you reach a certain horsepower requirement, diesel-electric hybrids are more efficient mechanically and economically - why else are locomotives and large merchant ships virtually all diesel-electric powered?

And I also think that hints at the answer to the follow-up question: at what point are they more economical? Since locomotives and large ships are pretty massive, I think it's a safe bet to say that with today's technology, the payoffs don't happen until you get to large scales. But the automotive industry, with its economies of scale, will eventually move to hybrid technology in large trucks/lorries and cars because it's more economical - mechanically and fiscally, and us sailors will finally see the trickle-down effect.

The physical efficiencies come from running a diesel (or gas/petrol) engine within its peak power curve where it burns fuel most efficiently. They aren't constant-torque machines like DC motors can be. So you size the engine to handle average loading of the generator/electric motor system, and use a moderate battery bank to handle the peak load conditions. Overall, it's more efficient power-wise. The manufacturing question becomes "how small can you scale it and still come out ahead $$$-wise". In the marine community, Lagoon is proof that we're coming pretty damn close.
__________________
Beausoleil is offline   Reply With Quote
Old 23-04-2008, 09:40   #21
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Don, you said nuclear subs periodically shut down their reactor and since you worked as a nuclear engineer on one, you would know. Do you mean just while tied to the dock or sometimes while underway and run on batteries alone? Do they have large battery banks like the old diesel subs had? All I know when I got to do a tour of a Los Angeles class is they would not let me go aft into the propulsion space. Just curious.

David
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 23-04-2008, 10:25   #22
Registered User

Join Date: Nov 2005
Location: Ohio
Posts: 2,311
My wife is a Senior Reactor Operator and the only time I know they throttle back to a hot idle is if they need to make a repair (leaking valve, steam leak, isolate equipment). It is big deal when it trips, they very much try to avoid that, especially in the summer when loads are high and we have a weekend planned on the boat.
__________________
Joli is offline   Reply With Quote
Old 23-04-2008, 11:01   #23
Registered User
 
coot's Avatar

Join Date: Feb 2006
Posts: 367
Images: 2
Quote:
Originally Posted by ess105 View Post
I'm not sure what hybrid system you are referring to when you say the speed loss is "huge". On the hybrid Lagoon 420's the cost of regeneration is at worst 1 knot.
1 knot out of how many? If you could make 10 knots, but only get 9 because you are charging the batteries, the loss is 10%. If there is enough wind for 5, but you only get 4, the loss is 20%. Maybe you don't agree with "huge", but I would say that 10-20% is "substantial".

The other side of that is that you have to sail to charge the batteries for much longer than you ran the engine. I would expect that if charging the batteries costs you 1 knot, then motoring at 5 knots for an hour would require you to sail more than 5 hours to replace the energy in the battery. Have you measured the actual ratio?
__________________
Mark S.
coot is offline   Reply With Quote
Old 23-04-2008, 11:19   #24
Registered User
 
Richkd's Avatar

Join Date: Apr 2008
Location: Aiken,SC
Boat: Hunter 280 AliMar
Posts: 34
Images: 3
Hey! Anyone making SOLAR SAILS yet? Ditch the diesel, load up on batteries and converters and Hoist the main! lol That is assuming you only sail when the sun shines.
__________________
Richkd ( Not Rich Kid)

"If the wind is free then why is sailing so dang expensive?"
Richkd is offline   Reply With Quote
Old 23-04-2008, 12:04   #25
Registered User
 
Jackstee's Avatar

Join Date: Nov 2006
Location: Presently liveing and working in Pakistan
Boat: HT 26. Currently in Mallorca
Posts: 98
Hi Guy's

Actually I did 7 years on a nuclear boat and we used to shut down fully the "Kettle" every 3 months for maintenance. This during the regular schedule of 3 months on, three months off. I was always called to start the diesels to do a "snort" and it earned me the right to have to stay on board for the first couple of days until we were on shore power.
Also, I did three reactor changes during that period and had to leave nuc boats after those 7, as I had, had, my lifetime dosage.

That caused me to leave the RN, as boats were great and I couldn't think of life after them(Sad eh)
However it actually worked out not bad at all.

Steve
__________________
I'll be onboard soon.
Jackstee is offline   Reply With Quote
Old 23-04-2008, 13:51   #26
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
Quote:
I would expect that if charging the batteries costs you 1 knot, then motoring at 5 knots for an hour would require you to sail more than 5 hours to replace the energy in the battery. Have you measured the actual ratio?
I am glad you posted that. I was goign to do the same. Energy out means you have to put the same energy in plus losses. This either comes from loss of speed or longer time. One or the other. There are no free luches. If the propellor takes 10Hp to turn it and push the hull through the water at say 10kts, then it is goign to require the same energy to spin the propellor in the water to replace that energy, Plus longer to make up for the losses. That is a lot of resistance under the water. If there is no resistance, the propellor will not turn. The max resisitance will be 10Hp back in. But we all know the extreme inefficiencies do not allow the effort to reach 10Hp. So the effort must be applied over a longer time.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 23-04-2008, 15:15   #27
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
You are right. One spends much longer putting the energy in than taking it out. I've not had enough time on the boat to measure this. Using the amp meters (which have their limitations too) the demand when powering was 75A max and supply when regenerating was 15A max. With losses you could be looking at 10:1 ratio and that's if one trusts the numbers which I don't. Ultimately all I'll trust is actual experience over the long term. That I can't share as I don't have it.

Having said that I can map this back to my typical usage profile. If there's wind then I like to spend as little time as possible under motor at both ends of the trip. If I'm doing short hops I probably won't put back in enough so somewhere along the way I'll have to run the generator for a bit. With the longer hops I expect to regenerate more than I need.

If their is no wind and I absolutely have to move then we're motoring. The hybrid setup is not very efficient in this mode so I'm hoping to avoid it. Our schedule will be largely open so I hope to minimize our dependency on this mode. Time will tell.

By the way if we do end up bobbing in the doldrums for a few days we'll have solar and massive Ahs available to us to run the on board systems without having to run gensets. I can think of worse places to be (like at work typing this message).

I think if people have the wrong expectations about hybrids then they'll be very disappointed. If they fit your usage profile then they have their attractions.
__________________
Dignity on the web
ess105 is offline   Reply With Quote
Old 23-04-2008, 17:30   #28
Senior Cruiser
 
mikereed100's Avatar

Cruisers Forum Supporter

Join Date: Dec 2005
Location: Santa Barbara
Boat: 46' custom cat
Posts: 1,571
Images: 2
Quote:
But for $800 I can buy a Ferris water generator
Not to drift too far, but where can you get a Ferris water generator for $800?

Mike
__________________
mikereed100 is offline   Reply With Quote
Old 23-04-2008, 17:55   #29
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
And how can it be hooked up to provide propulsion later on?
__________________
Dignity on the web
ess105 is offline   Reply With Quote
Old 23-04-2008, 21:37   #30
Registered User

Join Date: Nov 2006
Location: Vancouver, Can.
Boat: Woods 40' catamaran
Posts: 277
Quote:
why else are locomotives and large merchant ships virtually all diesel-electric powered?
Locomotives are D/E because they demand tremendous amounts of torque at zero speed (starting a train from a standstill). This is where electric motors shine. Large merchant ships are RARELY D/E (except cruise ships and ice breakers). I'm a commercial N.A. who designs these sorts of ships.

Cruise ships use D/E because they have a large "hotel" electrical load and can generate the large amounts of electricity and also use it for propulsion. They have redundancy of multiple gensets, and can raft mount them for reduced noise which is important for passengers.

Ice breakers use D/E for low speed prop torque reasons, and for damage resistance when milling ice with the props (electric motors don't mind as much as diesels being stopped by ice chunks).

There are other types of ships using D/E, but 95% are using straight diesels because they are the most efficient.

Frankly to me, the current crop of hybrid propulsion systems seem like a solution needing a problem. They won't be more efficient with the mechanical -> electric -> mechanical conversions required; they are a lot more complex and won't be easily repaired outside of first world countries.

If you want to generate power while sailing, I agree that a towed generator (or solar panels) are a much cheaper and more reliable option.
__________________

__________________
Evan is offline   Reply With Quote
Reply

Tags
diesel

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
Electric Outboard JohnnyC Auxiliary Equipment & Dinghy 23 28-02-2010 06:01
Hybrid Engines libellula Product or Service Reviews & Evaluations 78 12-09-2008 20:34
Electric and Diesel comparison Whimsical Multihull Sailboats 90 04-08-2008 16:38
420: Lagoon Diesel-Electric Problems PeterL Lagoon Catamarans 13 12-06-2007 07:28



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 10:40.


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.