Reply
 
Thread Tools Display Modes
 
Old 03-02-2011, 07:40 AM   #141
JD
Guru
 
JD's Avatar
 
City: New Bern NC
Country: USA
Vessel Name: Stella Di Mare
Vessel Model: Mainship 34t
Join Date: Apr 2010
Posts: 1,702
RE: Electric Boat Engines

Quote:
FF wrote:

The Wankle had many problems but was killed by the air police.

Most of the problems were in the the wiper seals in the early engines.* Mazda solved the problems and replaced a lot of engines free of charge in the 70's.*

Fuel mileage was a big problem.*

Redesigning of the exhaust port on the RX8 seems to have solved the emission and mileage problems for now.

Audi is using a small gas*Wankel running at 5k rpm to*power the gen set in their 2011 electric car.*

So it is not dead yet.
__________________
Advertisement

JD is offline   Reply With Quote
Old 03-02-2011, 07:41 AM   #142
Guru
 
jleonard's Avatar
 
Join Date: Jun 2008
Posts: 2,740
RE: Electric Boat Engines

http://www.liquidpiston.com/technologycycle/tid/1.html

I ran across the above a few weeks ago.
Interesting reading.
__________________

jleonard is offline   Reply With Quote
Old 03-02-2011, 02:33 PM   #143
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
RE: Electric Boat Engines

I just finished wading through this thread, whew, there sure are some interesting thoughts on the matter. There are also a couple of bizarre misconceptions as well. "My 85ft 90ton boat was originally powered with 16hp steam power ..." probably tops the list of claims that lead people into thinking diesel-electric offers up some magic solution to taking more power from a propeller than was delivered to the shaft.

That 16hp was almost certainly the "nominal horsepower" as described in the registration documents. This is a regulatory figure for the benefit of the tax collector, the class surveyor, and the licensing boards of the day. It was based partially on boiler firebox area, steam pressure, and a few other bits of 19th century voodoo. A common sized steamship of the late 1800s was just over 300 feet in length, admeasured out at around 2500 tons, and ripped through the water fully loaded at around 13 knots - all on around 300 nominal horsepower. The shaft horsepower produced by that engine was actually around 2000 or so.

That "giant tugboat diesel" was also a magic thing if the generator bolted to its butt could produce more power than it did. Come on guys, there is no free lunch, you lose power at each and every step of the process between the fuel tank and the propeller hub.

As far as diesel electric itself, it really doesn't offer much for recreational boaters unless they are into ship assist work or icebreaking on the side. Aside from cruise ships and a few tankers that use as much power at the dock as they do underway, and ferries that seem to be in near constant maneuvering mode, the only other benefit is the elimination of the reduction gear. This was why the T2 tankers of WW2 used steam turbine-electric drive, reduction gears were hard to come by during the war, they all went to warships.

The recent spate of diesel electric marketing built on the image and mystery of a propulsion system that lends itself to vaporware and voodoo engineering to sell to the uninformed. Read carefully through that entire thread, take a few notes of ideas and firm beliefs in certain claims then research each of them. I believe that anyone with a talent for research will quickly find where faith, hope, and reality diverge rapidly.

The idea that having near maximum torque available at zero shaft rpm is nice if you are chopping ice with your prop or starting a train or a car rolling from a full stop but our propellers live in a fluid medium ... they don't need massive torque at low rpm since they don't generate much thrust at low rpm ... that is why an engine can idle in gear. Few of the benefits touted in car advertisements apply to boats and that is among the many reasons the promises of a couple of years ago are left in the wake of a diesel turning a fixed pitch propeller.
RickB is offline   Reply With Quote
Old 03-03-2011, 05:04 AM   #144
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,531
RE: Electric Boat Engines

"The idea that having near maximum torque available at zero shaft rpm is nice"

You bet!!


My dream is a small flash boiler in the side car , and an almost silent bike that can clock 0-60 in 3 seconds !!
FF is offline   Reply With Quote
Old 03-03-2011, 09:53 AM   #145
Member
 
Winchester 73's Avatar
 
Join Date: Mar 2011
Posts: 8
RE: Electric Boat Engines

Quote:
FF wrote:


"The idea that having near maximum torque available at zero shaft rpm is nice"

You bet!!


My dream is a small flash boiler in the side car , and an almost silent bike that can clock 0-60 in 3 seconds !!
A dream indeed. Now get some power to the side car wheel and you'd have a two wheel drive drag racing machine.
Winchester 73 is offline   Reply With Quote
Old 03-03-2011, 11:05 AM   #146
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,721
Electric Boat Engines

It's easy to say Baugh Humbug. The April K DID experience a big increase in efficiency and there are many other significant benefits to DE drive. All DE is is a different way of transmitting power from the engine to the propeller. Diesel engines are heat engines so a reduction in heat loss would make them more efficient and DE drive does nothing to accomplish heat reduction. It all has to do w propeller loading and accomplishes what Fred's "cruise prop" does without the big disadvantages of over propping. One can adjust the propeller speed and engine load for any speed whereas the fixed pitch and gear system is only optimized at WOT when geared/loaded properly. The engine can run much more efficiently by operating at the ideal rpm to produce the power requited in any givin situation. Other advantages are extremely low boat speeds are possible without constantly going in and out of gear. The engine not being mechanically connected to the prop shaft can be operated on very soft engine mounts w very low levels of vibration. There are other advantages mentioned in the PMM article about the 43' OA April K. Perhaps the FAST system failed because of economic considerations. The Rotary Engine is not efficient because the force of the explosion in the combustion chamber is not directly applied to the piston and the seals produced lots of friction and thus heat loss.*73,
Looks like your boat's WLL is almost the same as hull OAL. Must be very fast in a stiff breeze. Looks like the sail area is maximized and the height of same is minimized as well. But if the hull was as long as the OAL including the bow sprit and boomkin you'd have more wetted surface but a very much reduced prismatic coefficient and increased WLL. Please go on the Sticky thread for boat pics and post pics.


-- Edited by nomadwilly on Thursday 3rd of March 2011 12:07:51 PM
Nomad Willy is online now   Reply With Quote
Old 03-03-2011, 11:31 AM   #147
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,265
RE: Electric Boat Engines

Quote:
nomadwilly wrote:

... Other advantages are extremely low boat speeds are possible without constantly going in and out of gear ...
If the electric motor is using less electricity than is being produced by the generator being powered by the diesel engine at*idle speed, and the battery banks are full,*what happens with the excess electric power?

*
markpierce is offline   Reply With Quote
Old 03-03-2011, 11:40 AM   #148
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,721
RE: Electric Boat Engines

Mark,
In DE there's no batteries. The electrical power generated goes directly to the boat motors (as opposed to boat engines).
Nomad Willy is online now   Reply With Quote
Old 03-03-2011, 11:51 AM   #149
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,265
RE: Electric Boat Engines

Missed the point, Eric.* Where does the unused electricity go (minimum generator speed producing more electricity than used by the electric motor)?
markpierce is offline   Reply With Quote
Old 03-03-2011, 12:15 PM   #150
Senior Member
 
Bendit's Avatar
 
City: Auckland
Country: New Zealand
Vessel Name: Pioneer
Vessel Model: Westcoaster 53 converted to pleasure
Join Date: Nov 2007
Posts: 283
Electric Boat Engines

Mark,
There isn't any excess electricity. The generator will produce on demand, just*as the alternator, on your engine stops producing*when the batteries are fully charged,*the generator will stop producing*electricity when the motor doesn't require any. *

After we have been*motoring for a couple of hours, and the solar panels are getting plenty of sun, the tachometer sometimes*goes to zero*because there is no field current getting to the alternator. To start the tacho, I need to add*an additional load - turn the interior lights on or an invertor.

-- Edited by Bendit on Thursday 3rd of March 2011 01:17:36 PM

-- Edited by Bendit on Thursday 3rd of March 2011 01:22:11 PM
__________________

Bendit is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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
Different size engines/same boat belizebill General Discussion 2 02-28-2011 02:24 PM
Noisy electric heads Delia Rosa General Discussion 45 02-19-2011 10:30 PM
Electric bike by VW Fotoman General Discussion 21 10-29-2010 05:07 PM
Electric Heads Forkliftt Other Trawler Systems 4 05-26-2010 09:35 PM
electric motors....again gns General Discussion 20 11-07-2008 04:34 PM




All times are GMT -5. The time now is 11:33 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012