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Old 03-31-2008, 04:18 AM   #121
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RE: Electric Boat Engines

"Why? Are you overpowered?"


The origional use of the vessel as a USN Utility required at least 10K service speed 12K unloaded..

At 7 or 8K the HP requirements are reduced by at least half , DD get less efficient at below 60% of rated power. Usual rule of thumb on a DD is 20hp per cylinder is nice 30 is OK .

Since we only burn 2 or 3 gph at our cruise , we generate 36 to 54hp for that speed.

The 3-71 can do 60HP to 90HP "forever", so would be a better choice if an engine replacement were required. But top speed would forever not be 12K.




You can down-rate your engine by changing to smaller pump/injectors.

On a DD the injectors ARE the pump (a rocker arm is the force and timing) so smaller injectors , advanced timing (fuel burns longer) and a more efficient SLOW SPEED driive setup works best.

Our origional setup was 90 injectors (235hp@2100)and 1.5-1 reduction gear with 27 dia 3 blade prop.

After economizing we now use 60 injectors (160HP @1200_ with advanced timing and a 3-1 reduction gear with 32x32 4 blade prop.

Thats about all that can be done cheaply.
Interesting that as light loaded as we are with work boat style interior , we can still pull 2100 and cruise at 1800 at almost 10K.

The Navy rates the boat fully loaded , we would need another 20,000 to 30,000 to be that heavy.

Better fuel burn can be done , but its not cheap.

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Old 04-01-2008, 06:06 AM   #122
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RE: Electric Boat Engines

The injectors are the pump...well I think the pump is the injector but anyway, we agree on that!

If you had heaps of space, you could have a 3-71 set up next to your 6-71 as an auxiliary engine with another shaft or on the same shaft don't know, and use the 3-71 full blast and when it's not enough, switch it off and get the 6-71 cracking

Neat..yet not cheap!
Do people actually have a small and a big engine and use it according to power requirement?...hum the drag of the prop that is not working could be a problem unless you have a CPP, actually two...

Is the boat on your avatar the one we are talking about?
Lovely!
I would like to see it doing top speed with a V8-92 full blast!


-- Edited by Marc1 at 02:38, 2008-04-02
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Old 04-02-2008, 03:59 AM   #123
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RE: Electric Boat Engines

Do people actually have a small and a big engine and use it according to power requirement?

No as the weight would be quite high . but OTS is a drive package as usually used in landing craft.

I have seen these in Boats & Harbors gov rebuilt on the palet for about $6K.

Two 6-71 coupled to a housing with a single (about 3 1/2 ) shaft output.

Either is independantly operable although normal is as a pair.

Either can be disconected with a lever , but the package MUST BE SHUT DOWN TO REINGAGE (DOG CLUTCH) .

Thought about getting a package and selling a 6-71 and installing a 3-71 but the current boat would require too much rebuild to handle the width , and a 3 1/2 shaft and gear is really expensive.

For a newbuild most folks would simply gamble on a modern electric injected engine , and 1/2 dozen spare brain boxes.

Or seal out a modern mechanical injected engine like the IVECIO.

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Old 04-02-2008, 07:37 AM   #124
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RE: Electric Boat Engines

Different application, of course, but it's pretty standard for bigger boats to have large and small gensets for different applications, i.e., to optimize loading.

Any reason you couldn't have twins powering the same shaft to serve the dual purpose of providing extra power when necessary or as an auxiliary engine in case one goes out?
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Old 04-03-2008, 04:50 AM   #125
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RE: Electric Boat Engines

"Any reason you couldn't have twins powering the same shaft to serve the dual purpose of providing extra power when necessary or as an auxiliary engine in case one goes out?'



Easily done with the above tranny.

Fuel system failure is still the biggest reason for engine stoppages, and two engines wouldn't help .

With $4.00 diesel the go fast folks will still be using 1100hp Mann's , and the usual Trawler owner would never , ever use it for speed.

For most a diesel or gas outboard on a suitable mount is still best "get home"insurance.

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Old 03-01-2011, 12:57 AM   #126
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RE: Electric Boat Engines

I'd like to know if any of your opinions have changed in the three years since this thread was started. I believe that in a full keel heavy displacement 40-45 foot trawler with a hull speed of say 8knts that the diesel electric would be more efficient than a conventional system of propulsion. The electric motor can turn a substantially larger propeller at slower speeds. Plus the generator could be placed in the most desirable position for the particular boat. What do you guys think and does anyone have any experience with the "electric Wheel" by Ferris I believe.

Just some color
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Old 03-01-2011, 03:11 AM   #127
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Electric Boat Engines

Boy it's going to be cramped in that little wheel house, thank god it's cold outside. (well it looks cold to me)

Benn

-- Edited by Tidahapah on Tuesday 1st of March 2011 04:11:31 AM
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Old 03-01-2011, 03:55 AM   #128
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RE: Electric Boat Engines

"I believe that in a full keel heavy displacement 40-45 foot trawler with a hull speed of say 8knts that the diesel electric would be more efficient than a conventional system of propulsion. The electric motor can turn a substantially larger propeller at slower speeds."


If it were that just a wheel slowdown made much difference , we would see boats with OTS 6-1 and 8-1 trannies to swing a 48 to 60 inch wheel at 250RPM .

The loss of 2 or 3% in a mechanical gear box would be minor.

The electric drives have about 5X- 10x the losses (without supercooled superconductors as the military uses) .

A simple big prop IS a few percent more efficient but a diesel at best (only in big sizes) is 50% efficient , and hanging alternators , generators , controllers and then using a not great electric motor does not ADD , it looses.

Whole different game when propulsion loads are the minor loads and the hotel loads are huge , cruise ship.
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Old 03-01-2011, 05:12 AM   #129
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RE: Electric Boat Engines

Has anything changed since the thread started . well for one the nordhavn mentioned as being built as a diesel electric has been converted to a convential diesel drive and the head of nordhavn has publicly described the project as a train wreck.
Nice theory but still not viable.
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Old 03-01-2011, 09:49 AM   #130
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Electric Boat Engines

I am no engineer, but common sense tells me that the most inefficient mechanical piece of engineering we are still using today is the compression (heat engine ).

it is the almighty "crank shaft " *?

That was ok ! *for Henry Ford and the industrial revolution.
A piston will go to TDC *and stop then reverse direction, that is the same as a base ball bat hitting the ball it is like energy stops and starts.


Please, can someone tell me why the "Wankle engine" is no more .


I would have thought that *the elimination / reducing of friction *would be the best place to start.


Tell me does a one cylinder engine have less friction than a 12 cylinder *RR engine.


Power Boats are particularly vulnerable to losses caused by friction.


Gentlemen we are Ex sailboat people ( rag men) , we found back then the wind is free .


Are we all faced with going back to the future.

Wind: solar; May be Natural gas; steam and so on could be the answer.


Who has not seen the movie *Mad Max * a story of the end days.


To get away from the road rage and madness,yesterday we cruised around 8 kts all day, we felt that we were hardly moving, however we enjoyed the moment , with no where to go and all day to do it in .


Is speed *the relation ship between time and distance all that controls us .


I asked Mavis, are you happy?


Donald & Mavis.


We are *the Mystic knights of the sea.
We are from the sea .
We are of the sea.
We are*by the sea















-- Edited by SOMERS on Tuesday 1st of March 2011 10:53:28 AM
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Old 03-01-2011, 04:22 PM   #131
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RE: Electric Boat Engines

I'm not a go fast guy. I'm actually a go heavy and go slow type guy. This electric motor will push a 45 foot 16 ton vessel to hull speed with power to spare burning only 0.5 gallons of diesel per hour. I have to say I'm coming from sail and don't own a trawler. If diesel continues to become more and more cost prohibitive I may never be able to afford a power voyaging vessel. My ideal boat would have the shape of a sailing vessel below the waterline, and a north sea trawler above. 0.5 gallons an hour is doable. One gallon per hour is doable. My 28' waterline 7 ton sailboat will cruise at hull speed with 12hp burning 3/4 gallons per hour but her salon is cramped and she lacks a pilothouse.
http://www.solomontechnologies.com/st58.htm
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Old 03-01-2011, 05:09 PM   #132
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Electric Boat Engines

For awhile I was going to buy a 35-40' sailboat and convert it to a trawler. I reasoned the hull would take about half the power to drive as a FD trawler and 1/3 to 1/4 as much as a typical SD trawler. Bought the Willard instead.
There was an article in the June 03 issue of PMM about an 43' Ocean Alexander that had twin Cats that was converted to diesel electric power using bus components. The OA was found to be 22% more efficient. The article talks about propeller and engine loading advantages of the DE system.
I just did a search on the FAST system and the web sites and phones don't work anymore.
Looks like it did'nt work out but then the company could have been reorganized. Further searches may produce another DE product.

-- Edited by nomadwilly on Tuesday 1st of March 2011 06:26:24 PM
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Old 03-01-2011, 07:19 PM   #133
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RE: Electric Boat Engines

Willy, how many gallons are you burning per hour at what HP? The willard is very cool, and I imagine a fine seakeeper.
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Old 03-01-2011, 08:28 PM   #134
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RE: Electric Boat Engines

Quote:
SOMERS wrote:

I am no engineer, but common sense tells me that the most inefficient mechanical piece of engineering we are still using today is the compression (heat engine ).


it is the almighty "crank shaft " *?

That was ok ! *for Henry Ford and the industrial revolution.
A piston will go to TDC *and stop then reverse direction, that is the same as a base ball bat hitting the ball it is like energy stops and starts.


Please, can someone tell me why the "Wankle engine" is no more .


I would have thought that *the elimination / reducing of friction *would be the best place to start.


Tell me does a one cylinder engine have less friction than a 12 cylinder *RR engine.


Power Boats are particularly vulnerable to losses caused by friction.


Gentlemen we are Ex sailboat people ( rag men) , we found back then the wind is free .


Are we all faced with going back to the future.

Wind: solar; May be Natural gas; steam and so on could be the answer.


Who has not seen the movie *Mad Max * a story of the end days.


To get away from the road rage and madness,yesterday we cruised around 8 kts all day, we felt that we were hardly moving, however we enjoyed the moment , with no where to go and all day to do it in .


Is speed *the relation ship between time and distance all that controls us .


I asked Mavis, are you happy?


Donald & Mavis.


We are *the Mystic knights of the sea.
We are from the sea .
We are of the sea.
We are*by the sea















-- Edited by SOMERS on Tuesday 1st of March 2011 10:53:28 AM
*
Could it be the Wankel bit the dust because they were loud, cranky, used too much fuel, made a funny buzzing sound and were pretty much a disaster??

I think somebody watched too many movies on TBS last weekend... The Postman... Water World maybe???** I think the whole reason to spout the "end of the world gloom and doom" and "we are running out of Oil " mantra has been pretty well debunked.. even Al Gore is quiet.* Now if you want to push alternative tech for national security I am on board.* I would love to have a trawler with a flux capacitor but it is a ways away...
HOLLYWOOD

*
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Old 03-01-2011, 08:30 PM   #135
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RE: Electric Boat Engines

Winchester, if I was twenty years younger, I'd be looking for a boat like yours.
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Old 03-01-2011, 08:54 PM   #136
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RE: Electric Boat Engines

You know I think the average age of circumnavigators is a couple who are over 60. This is a guess but I would imagine 99% of circumnavigations are under sail. All that being said I'd like a trawler.
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Old 03-01-2011, 09:16 PM   #137
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RE: Electric Boat Engines

73,I repowered a few years ago. Had a 4-107 Perkins and installed a 4-107 Mitsubishi. I call the Mitsu a 4-107 because it has the same # of cylinders, the same bore and stroke and it's also an inline eng w pre-chamber combustion chambers. I bought it because we had decided to move to Alaska and most of the time we're out in the wilderness and in some rather exposed areas where running a 35 yr old eng is less desirable than running a new one. The excellent electric glow plugs/heaters also factored in. I picked the Klassen built engine as they offered the most extensive range of custom features and they dealt extensively in Alaska and mostly w fishermen and other commercial business.
The Mitsu S4L2 develops 37hp at 3000rpm with a rather large nylon fan rigged as an industrial eng. Exactly the same engine is marketed by Vetus (42hp) and Westerbeke (44hp). I'm proped for 3000rpm at WOT and cruise at 2300 85% of the time and at 2500rpm some of the time. The engine is rated for WOT for one hour and I've never done that. At 2300 the W30 makes 6.15 knots and at 2500 6.4 knots. Fuel burn is less than but almost exactly 1gph. However the 1gph computation was made while the engine was being broken in and I gained at least 150rpm when broken in so one can assume actual burn rate now is probably closer to .9gph. I think w a 27hp Yanmar the Willard would run comfortably at 6 knots. 27hp would be the lower end of the practical power range for the W30 Willard. Several W30s have 55hp and one chap has 80hp * *...all a waste in my opinion. The W30 rolls a bit but I have no plans to get stabilizers. Join the Willard Boat Owners Group on Yahoo Groups to learn almost anything about a Willard you would like to know. The other guys have seen it but for you 73 here's a better pic of my boat. Willard made 5 models w the same hull as mine.
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Old 03-02-2011, 03:58 AM   #138
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RE: Electric Boat Engines

Please, can someone tell me why the "Wankle engine" is no more .Pollution is directly related to the combustion surface area.

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

With the new urea /hotter cat anti pollution garbage still not working in trucks , it is doubtful the Wankle will make a comeback.
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Old 03-02-2011, 06:23 AM   #139
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RE: Electric Boat Engines

Hummm, what is the Mazda RX 8? A powerful rotary engine in a very good car.
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Old 03-02-2011, 07:32 AM   #140
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RE: Electric Boat Engines

Quote:
SOMERS wrote:I am no engineer, but common sense tells me that the most inefficient mechanical piece of engineering we are still using today is the compression (heat engine ).
That might be better described as "common misperception."

The most efficient device we have for converting liquid fuel to rotary motion today is a very large diesel engine. That engine is over 50 percent thermally efficient and produces one horsepower for each 126 grams of fuel burned.

To put that into perspective, Eric's SL42 burns about 182 grams to produce each horsepower. FF's darlings suck up 190 to do the same job.

And it's not the crankshaft that stands in the way of efficiency, the most widely used marine gas turbine in use today burns just under 170 grams to put a horsepower into the shaft.

*
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