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.

FF

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

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.

FF

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?

"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.

FF

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

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

"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.

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.

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

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

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

Willy, how many gallons are you burning per hour at what HP? The willard is very cool, and I imagine a fine seakeeper.

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
*

Click to expand...

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

*

Winchester, if I was twenty years younger, I'd be looking for a boat like yours.

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.

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.

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.

Hummm, what is the Mazda RX 8? A powerful rotary engine in a very good car.

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 ).

Click to expand...

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.

*

FF wrote:

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

Click to expand...

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.

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

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

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.

"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 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 !!

Click to expand...

A dream indeed. Now get some power to the side car wheel and you'd have a two wheel drive drag racing machine.

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

nomadwilly wrote:

... Other advantages are extremely low boat speeds are possible without constantly going in and out of gear ...

Click to expand...

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?

*

Mark,
In DE there's no batteries. The electrical power generated goes directly to the boat motors (as opposed to boat engines).

Missed the point, Eric.* Where does the unused electricity go (minimum generator speed producing more electricity than used by the electric motor)?

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