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Old 12-22-2012, 11:31 AM   #101
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Could the reason why diesel/electric is not popular in boats be because boats do not use multiple gears as do land based vehicles?
In a word, no.

In more than a word, what do you mean by "boats?" There are many marine applications where D/E makes a great deal of sense for many reasons.


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Can you see clutching in and out to change locomotive gears while accelerating?.
Yes, the "clutching" is performed automatically in the very commonly used and very efficient geared locomotive drives used in European railways.
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Old 12-22-2012, 11:38 AM   #102
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Jeff

I can assure you my boat has a gearbox - Hurth. It has a 2.5:1 reduction gear with a reverser. Some in fact claim that marine gearboxes have clutches. Furthermore, the propeller is variable speed as I move the throttles up and down. For our slow trawlers, what more do we need and why?
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Old 12-22-2012, 11:43 AM   #103
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I went to Antarctica and nearly the North Pole on diesel electric boats...

On the way to Iceland...one of the main motors burned up as the insulation on the windings was so bad (WWII vintage)...

We still continued north to within 400 or so miles of the pole on one motor and came all the way back on one engine and a little over 8 knots via Sweden and Denmark liberty/political calls...
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Old 12-22-2012, 11:56 AM   #104
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Although it's interesting that the large tankers, bulk carriers, and container ships built today mostly seem to be diesel powered, not diesel-electric or turbine. I'd like to know why that is.
Because those ships operate for extended periods at a constant speed and load and have hulls optimized for that purpose and driven by engines and propellers optimized for extended operation at a specific power output and ship speed.

There is no advantage to adding another conversion between the fuel tank and the propeller.

Some "parcel tankers" that operate in coastal trades are diesel-electric because a tanker may consume as much power offloading as it does transiting.

Many LNG tankers use steam turbine propulsion because they can utilize the boil-off gas for fuel. The Japanese are building several now and are the leading supplier of boilers these days.
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Old 12-22-2012, 12:09 PM   #105
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Could the reason why diesel/electric is not popular in boats be because boats do not use multiple gears as do land based vehicles? Can you see clutching in and out to change locomotive gears while accelerating?. Electric eliminates the clutch and gearbox, neither of which is used in recreational boating.
Most railroad locomotives have eight engine settings, referred to as "runs"--- run six, run eight. I have no idea how the system works but you can hear the prime mover (diesel engine) "shifting" as the locomotive accelerates and you can see these "shifts" reflected by in the exhaust plume.
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Old 12-22-2012, 12:33 PM   #106
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Most railroad locomotives have eight engine settings, referred to as "runs"--- run six, run eight. I have no idea how the system works but you can hear the prime mover (diesel engine) "shifting" as the locomotive accelerates and you can see these "shifts" reflected by in the exhaust plume.
Those "shifts" are merely changes in power/throttle settings. Possibly that's due to the throttles being electrically controlled. Most all the diesel-electric railroad locomotives were/are built this way such as from builders EMD, ALCO, and GE. This allowed one engine crew to control multiple locomotives (units). One builder, Baldwin (now long-defunct), however, had pneumatically controlled throttles which allowed "infinite" power settings as there were no "notches." Here, air hoses rather than electrical wires connected locomotives' throttles. Baldwin locomotives couldn't be "MUed" with other builders' locomotives.

Engine controls of a 1950s-era GE 70-ton diesel-electric locomotive (photo taken in 2009):

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Old 12-22-2012, 12:37 PM   #107
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Jeff

I can assure you my boat has a gearbox - Hurth. It has a 2.5:1 reduction gear with a reverser. Some in fact claim that marine gearboxes have clutches. Furthermore, the propeller is variable speed as I move the throttles up and down. For our slow trawlers, what more do we need and why?
Rest assured that your gear box has clutches just like the automatic transmission in your car has them. They are in what is called a clutch pack and are either engaged, which means compressed together or not engaged which then allows the engine to turn without transmitting power to the out put shaft. You control if they are in gaged or not buy the lever you push at the helm. One difference in your car and the boat is the car has one more link to the engine by way of the Torque Converter where the boat has a Damper Plate. This is a mechanism that allows your car to stay in gear while you are at a stop light yet there is no forward motion. The torque converter is a turbine affair in which one part is connected to the flywheel and the other is connected to the front shaft on the transmission. As the engine turns at low speed, idle, the Stator and the Rotor turn by each other, but as the engine speed increases the rotor causes pressure on the stator and the stator starts to move thus making the car move. A Torque Converter would not be needed in the car but then you would have to select drive, neutral or reverse constantly. When you were approaching a light you would have to shift into neutral every time just as you do on the boat as you approach the dock. Other wise the engine would stall. The boat transmission is simple because it only needs to select one ratio so it has only one clutch pack where the car transmission needs to select between several ratios and thus becomes more complicated by way of several clutch packs and other items.

More than anyone really wants to know about either I'm sure.
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Old 12-22-2012, 01:10 PM   #108
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Perhaps the operative word is control.

You can putz around in a harbor at 1 knot and stay in "gear". I think you can reverse instantly at full power AND torque and then without a pause for the clutches slam into reverse. Don't remember the details perfectly as my PMM is in a box still but DE drive is has some really great advantages. Don't remember about efficiency though.
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Old 12-22-2012, 01:17 PM   #109
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Eric, my builder warned me about changing from forward to reverse saying it must be done at idle/near-idle engine speeds to avoid risk of damage.
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Old 12-22-2012, 02:16 PM   #110
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Eric, my builder warned me about changing from forward to reverse saying it must be done at idle/near-idle engine speeds to avoid risk of damage.
Mark,

I'm sure that the damage can be real. It is a lot like slaming into a wall at 50MPH so as you can go backward. A lot easier to slow down then go the other direction. Think about the twisting force on the shafts inside the transmission, the prop, the drive shaft. Even though the damper plate is traveling in the same direction the force of full pressure, then no pressure and then full pressuree all with in a second or so is scary.
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Old 12-22-2012, 02:34 PM   #111
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I have no idea how the system works but you can hear the prime mover (diesel engine) "shifting" as the locomotive accelerates and you can see these "shifts" reflected by in the exhaust plume.
Those "shifts" are the transitions between series and parallel operation of the traction motors. There is a very short period during the transition when no power is delivered. That is what gives the impression of a gear shift as in a truck.

The "runs" or "notches" are governor limits that control the maximum amount of power available to the traction motors in a given configuration. They reduce the risk of overloading a motor by limiting the amount of power the engine can produce.
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Old 12-22-2012, 03:06 PM   #112
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If I cruise 10hours in idle , I must full power at least 1minute twicw a day to clean the engines. Is it the same with gasoline engines?

NO. And 1 min will not clean the carbon buildup behind the rings, high piston temperature and time is required.

Perhaps a half hour ,,.

The nicest engine room I was able to visit was on a 55-60 ft Motor sailor called Feng Shuay (SP?)

It had a fine setup with the engine mounted an the bow!

The boat was heavy so a 6-71 at 2500lbs was not noticed , the noisemaker was there too.

The engine was walk around standing headroom, and the hull at deck level provided huge storage at eye level.

The shafting was std truck with the tranny at the usual after position absorbing thrust .Windlass , mechanical from the 6-71 with a clutch, no blown fuses.

With todays far lighter engines , and the fact that 60 years later the fore peak still sucks as a place to be , I think this configuration would be of far more interest than a D cell powered boat.

When the decimal moves 2 places on batts , smaller .,lighter, cheaper and far far more powerful, perhaps a noisemaker free (for a week) boat could be built.
yes, electric is quiet but without a noisy generator to run it the technology isnt really applicable to marine use at this time. I thought of solar but its not really possible to put enough solar cells on a small vessel to do the job without generqator backup. Has anyone tryed such a thing I wonder?

As for carbon, why not use a fuel additive to keep the carbon build up in check? I've beern doing that for years in my D pickups and cars.
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Old 12-22-2012, 04:54 PM   #113
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Mark and JD,

I was talking about diesel-electric drive not clutching reverse gears. I don't think you need to pause or de-throttle w DE systems.

And Mark I definitely do go to idle and pause for 1 to 3 seconds before shifting into reverse unless it would save me from crashing into the float or another boat.
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Old 12-22-2012, 06:01 PM   #114
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yes, electric is quiet but without a noisy generator to run it the technology isnt really applicable to marine use at this time. I thought of solar but its not really possible to put enough solar cells on a small vessel to do the job without generqator backup. Has anyone tryed such a thing I wonder?

As for carbon, why not use a fuel additive to keep the carbon build up in check? I've beern doing that for years in my D pickups and cars.
Yes for once the boating mags and their infinite advertisements have a company that's advertising it...sorry I don't remember the name...I skimmed over it as useless for the next 5-10 years...WAYYYYY too expensive for my tastes/abilities...
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Old 12-22-2012, 06:48 PM   #115
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Aren't pod-drive cruise ships, and the like, diesel-electric driven? Are the pod drives on the new trawlers like this or is it more like a stern-drive system with gears and CV joints?
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Old 12-22-2012, 06:55 PM   #116
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Aren't pod-drive cruise ships, and the like, diesel-electric driven? Are the pod drives on the new trawlers like this or is it more like a stern-drive system with gears and CV joints?
thats a good question. Will ve tolook into that.

This looks interesting and they apear to be electric motor driven you were right
http://www.nauticexpo.com/boat-manuf...ips-20116.html
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Old 12-22-2012, 06:58 PM   #117
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Aren't pod-drive cruise ships, and the like, diesel-electric driven?
Most all cruise ships, pod-drive or not, are diesel-electric powered. They have multiple diesel engines. They turn on as few or many as needed to meet the power needs at any particular time.
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Old 12-22-2012, 07:23 PM   #118
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Most all cruise ships, pod-drive or not, are diesel-electric powered. They have multiple diesel engines. They turn on as few or many as needed to meet the power needs at any particular time.
So they are using railroad tecknology. When i finally find what i am looking for in a DeFever 40-41 i plan on experimenting with electric power in a more conventional form. I think an ac electric motor generator driven power system that will power the original prop shaft arrangment the old bost was launched with might end up being very fuel efficient.
Very interesting idea multiple engines for diferent load conditions. I don't remember much of my electric motor training but a single electric motor wired to run on different voltages phases for different loads............naw, way to complicated for a 7-9kt vessel. But if she had a hulll designed to go fast then it would make sense. Wow! Just think of it a trawler that can go freeway speeds!! YAHOOOO

Hummmm......Guess thats why they use it on cruise ships and not toy boats
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Old 12-22-2012, 07:37 PM   #119
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An interesting arrangement would be a single, keel-protected propeller shaft/propeller turned by an electric motor and two small primary engines and possibly a genset connected to generators. For moving at up to hull speed, one primary engine would be used. Faster speeds (assuming the appropriate hull shape) could be provided by using both engines at the same time. If one primary engine broke down, there would still be the second, or even the genset if both primaries failed. Steering wouldn't be hampered by having only one of two offsetted propeller shafts not operating.
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Old 12-22-2012, 07:47 PM   #120
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So they are using railroad tecknology. When i finally find what i am looking for in a DeFever 40-41 i plan on experimenting with electric power in a more conventional form. I think an ac electric motor generator driven power system that will power the original prop shaft arrangment the old bost was launched with might end up being very fuel efficient.
Very interesting idea multiple engines for diferent load conditions. I don't remember much of my electric motor training but a single electric motor wired to run on different voltages phases for different loads............naw, way to complicated for a 7-9kt vessel. But if she had a hulll designed to go fast then it would make sense. Wow! Just think of it a trawler that can go freeway speeds!! YAHOOOO

Hummmm......Guess thats why they use it on cruise ships and not toy boats
NOT railroad tech...been around for a LONG time in the maritime industry...big electric motors driven by multiple gensets...I believe the USCGC Glacier 9wwii vintage) had 10 Gensets driving the motors and powering the vessel. She had 2 of the largest electric motors ever built at around 3 stories high.
She was a 15+ knot vessel, designed to break thick ice and ran as many gensets as needed to carry the drive and house load. At any given time one or more were being rebuilt underway.
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