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10-21-2015, 12:38 PM
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#1
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
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Yanmar re-enters 50hp Diesel outboard market with Neander!!!!
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Peter.
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10-21-2015, 01:10 PM
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#2
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Senior Member
City: Knoxville
Vessel Name: Pura Vida
Vessel Model: 08 Meridian 490 Pilothouse
Join Date: Apr 2014
Posts: 316
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I wish we could purchase a NEANDER Shark Turbo Diesel outboard engine in the US.
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10-21-2015, 01:34 PM
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#3
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
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Quote:
Originally Posted by Pura Vida
I wish we could purchase a NEANDER Shark Turbo Diesel outboard engine in the US.
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Ah, I didn't realise it doesn't comply with US regs; are you sure you can't import it from Europe?
I've sent off an email to get the price.
What do you think: 2x as much as a gasoline 50hp?
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Peter.
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10-21-2015, 01:40 PM
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#4
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
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Have a look at the engineering: wtf!!!
Technology : Neander Shark
The key enabler for a dual crankshaft engine with a constrained piston movement by two con-rods with theoretically no piston side forces is provision for forgiveness towards tolerances, which can lead to off-design positions of the piston in its cylinder bore and unfavorable mechanical effects like scuffing, sticking or simply higher friction as the least bad of effethis
PS: I had to look at the photos to understand this....lol.
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Peter.
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10-21-2015, 03:15 PM
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#5
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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Neat stuff!!!
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10-21-2015, 03:21 PM
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#6
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
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Quote:
Originally Posted by Ski in NC
Neat stuff!!!
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Sounds like a complicated solution to a simple problem: vibration .
What's wrong with a counter weigh/damper on the crank/flywheel?
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Peter.
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10-21-2015, 04:02 PM
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#7
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Senior Member
City: louisiana
Join Date: Aug 2014
Posts: 234
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Quote:
Originally Posted by Rustybarge
Sounds like a complicated solution to a simple problem: vibration .
What's wrong with a counter weigh/damper on the crank/flywheel?
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Increase weight??
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10-21-2015, 04:16 PM
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#8
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
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Quote:
Originally Posted by rardoin
Increase weight??
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I think a standard 50hp gas outboard would be about 100-110kg, so 175kg for the diesel is pushing the limits on the transom of a planing hull designed for half the load.
I'm thinking you would need a redesigned hull to take the extra weight.
Maybe its designed for displ. Speeds?
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Peter.
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10-21-2015, 04:28 PM
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#9
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
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Posts: 6,194
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Quote:
Originally Posted by Rustybarge
Sounds like a complicated solution to a simple problem: vibration .
What's wrong with a counter weigh/damper on the crank/flywheel?
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A two cylinder four stroke is an infernal machine. With two pistons moving together, firing is 360deg, but dynamic balance is HORRIBLE. Counterweights on the fw or crank can help, but they provide a rotating force, the piston force is linear along bore axis. Only way to cancel is to have a counter rotating balance shaft. Which these guys basically get with the two cranks.
Only thing with worse vibes is a single cyl, and not by much!!
Better balance can be had by a 180deg crank, with pistons moving opposite. But then firing order is 180deg/540deg which provides it's very own special flavor of shake at low rpm. Also sounds horrible. Sounds like a misfiring three cyl. And balance of the 180deg crank is better, but still sucks.
The Neander design looks like it has or nearly has perfect mechanical balance. Weights added to the CR cranks will act linear like the piston forces and should be able to nearly cancel.
I think also the low rpm shake from firing impulses is canceled too.
Maybe they could use this design for the snotty running four stroke two cyl gassers.
Only downside I see is cost. Low volume Euro stuff is expensive.
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10-21-2015, 04:47 PM
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#10
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Guru
City: I need a bigger boat!
Vessel Model: Cheetah 25' Powercat.
Join Date: Aug 2014
Posts: 925
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Quote:
Originally Posted by Ski in NC
A two cylinder four stroke is an infernal machine. With two pistons moving together, firing is 360deg, but dynamic balance is HORRIBLE. Counterweights on the fw or crank can help, but they provide a rotating force, the piston force is linear along bore axis. Only way to cancel is to have a counter rotating balance shaft. Which these guys basically get with the two cranks.
Only thing with worse vibes is a single cyl, and not by much!!
Better balance can be had by a 180deg crank, with pistons moving opposite. But then firing order is 180deg/540deg which provides it's very own special flavor of shake at low rpm. Also sounds horrible. Sounds like a misfiring three cyl. And balance of the 180deg crank is better, but still sucks.
The Neander design looks like it has or nearly has perfect mechanical balance. Weights added to the CR cranks will act linear like the piston forces and should be able to nearly cancel.
I think also the low rpm shake from firing impulses is canceled too.
Maybe they could use this design for the snotty running four stroke two cyl gassers.
Only downside I see is cost. Low volume Euro stuff is expensive.
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Thanks for your explanation; very interesting..
Here's a video showing the setup:
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Peter.
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10-21-2015, 05:59 PM
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#11
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Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
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Posts: 18,738
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Counter weights on a single or 360 twin if heavy enough can counter Ballance for up and down but when the counter weights are thrown sideways (as in 90 or 270 degrees) there's nothing to the side to counter weight wise so most engineers compromise by giving the counter weight about 1/3 of a total up and down Ballance. Old Brittish twin cyl motorcycles were all (almost) w 360 cranks and were quite smooth to about 50% rpm max but terrible above that.
For a smooth engine I've thought a 90degree V3 w the single cyl side having a cyl about twice the size as the twin cyl side would be good. No counterweights required ... I think.
But this Yanmar twin connecting rod engine will be very widespread soon .. I think. The Pistons coming almost straight down on the crank pins is a wonderful new design. If they have it heavily patented they should make millions with it.
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Eric
North Western Washington State USA
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10-21-2015, 06:44 PM
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#12
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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This would also work on a single cyl.
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10-21-2015, 06:46 PM
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#13
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Senior Member
City: Markham
Vessel Name: currently boatless
Join Date: Apr 2015
Posts: 280
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I'll bet these engines will show up on the new pocket trawler Ken Fickett is designing at Great Harbour.
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10-21-2015, 07:17 PM
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#14
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Guru
City: Galveston, Texas
Vessel Model: 24" El Pescador
Join Date: Nov 2014
Posts: 743
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Quote:
The key enabler for a dual crankshaft engine with a constrained piston movement by two con-rods with theoretically no piston side forces is provision for forgiveness towards tolerances,
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Does this mean it will be built with hand tools in a country with the cheapest labor?
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10-21-2015, 07:37 PM
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#15
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Guru
City: Sydney
Join Date: Jul 2015
Posts: 1,646
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The big question is do we really need a expensive heavy hard to maintain 50hp diesel when we have so many cheap light 4 stroke petrol outboards that have a proven history ?
And as my late father would say DON'T mention the WAR
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10-21-2015, 08:17 PM
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#16
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Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,738
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Quote:
Originally Posted by Ski in NC
This would also work on a single cyl.
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Ski,
What about torsional vibration?
This would be an engine w more crankshafts than cylinders?
gaston,
"Light 4 stroke gas ... " never heard that one before.
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Eric
North Western Washington State USA
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10-21-2015, 08:32 PM
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#17
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Guru
City: Sydney
Join Date: Jul 2015
Posts: 1,646
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Quote:
Originally Posted by manyboats
Ski,
What about torsional vibration?
This would be an engine w more crankshafts than cylinders?
gaston,
"Light 4 stroke gas ... " never heard that one before.
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The Honda 50 is within a few kg of the Yamaha 50 2 stroke so yes light 4 stroke
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10-21-2015, 09:48 PM
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#18
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Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,738
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gaston,
Yamaha is offering a 50hp 2 stroke?
Must be like the Evinrude E-tec. And they aren't light.
Only light OB is an old one.
I'll look up the Yamaha though.
Went to the Yamaha site and the only 50hp engine was SOHC and 249lbs or 113kg. The Yanmar diesel OB is 175kg.
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Eric
North Western Washington State USA
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10-21-2015, 10:33 PM
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#19
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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Quote:
Originally Posted by manyboats
Ski,
What about torsional vibration?
This would be an engine w more crankshafts than cylinders?
gaston,
"Light 4 stroke gas ... " never heard that one before.
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Torsional vibes are an issue with long multi cylinder crankshafts. Crank flexes in the twisting sense, and has a natural frequency that can get excited by firing pulses. Not really an issue with few cylinders, the cranks are relatively stiff in the twisting sense.
But I do wonder about gear lash between the cranks, and how ever they extract the output. Guess one crank is driving output shaft, other is geared to the main, so a prime candidate for gear lash rattle.
Proof is in the pudding!! I'd love to see the details and fiddle with one. Some elegance seen in the casual glance!!
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10-22-2015, 05:44 AM
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#20
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Guru
Join Date: Oct 2007
Posts: 22,553
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WHY a Diesel?
With many new fancy gas engines creating 14hp per gal/hr and diesel 15%+ more costly than gas why bother?
Surely you wont be up in the 1,000 - 2,000 hours of operation per year that might justify a diesel?
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