They have two propellers so in that sense they are twins. But they are not twins in the sense that our GB is a twin because the two props are not of equal size, positioned equidistant from the keel or centerline, or powered by engines developing equal power. Therefore one cannot perform the same kind of maneuvers using differential thrust (and rudders and power) that one can perform with an actual twin-engine boat.
Single vs Twin: It's Baaaaack!
- Thread starter markpierce
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The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
They have two propellers so in that sense they are twins. But they are not twins in the sense that our GB is a twin because the two props are not of equal size, positioned equidistant from the keel or centerline, or powered by engines developing equal power. Therefore one cannot perform the same kind of maneuvers using differential thrust (and rudders and power) that one can perform with an actual twin-engine boat.
Northern Spy
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Not sure if Alco made an opposed piston engine. May have, they sure built a lot of diesels. I learned on a Fairbanks Morse, which had some use on locomotives as well.
OP
OP
markpierce
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Correct ... Fairbanks-Morse.
OP
OP
markpierce
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Many nineteenth-century ships with engines carried sail rigs for "get-home" propulsion in case of engine failure.
ALCO made it's own diesel engines by virtue of buying an established diesel engine manufacturing company in 1929 or thereabouts. To my knowledge the engines made for ALCO's diesel-electric locomotives by this company were all conventional designs.
bfloyd4445
Guru
I cant find the link. but this is similiar except that it uses four pisrones in teo cylinders. The one that impressed me used two pistonsw which fired both up and down making the two cylinders into four. The piston top and bottom were the dame and the wrist pins extended to operate rods to the crank
EcoMotors OPOC Two Stroke Engines – Opposed Piston Opposed Cylinder
That's the same basic layout the Fairbanks-Morse of WWII had. You said in your first post that this new engine had one piston traveling back and forth in a single cylinder, thus creating two combustion chambers.
But apparently that's not the case. If it's the way your second post describes it, this is nothing new at all but dates back to the 1930s.
But apparently that's not the case. If it's the way your second post describes it, this is nothing new at all but dates back to the 1930s.
Northern Spy
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Similar, but not the same. The Fairbanks Morse D8 1/8 had two parallel crankshafts. Fewer moving parts. The lower crank was timed 12 degrees ahead of the upper crank in timing so less hp went to the upper crank. The upper crank drove the scavanging blower. The lower crank was the prime mover, in my case it was a generator and the fuel racks were controlled by a synchronous governor. No valves just ports. Great design.
RickB
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Here is a quick review: http://www.mikalsen.eu/papers/FPEreview.pdf
Here is a Russian application used as an air compressor:
Attachments
RickB
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The OP idea goes back a lot further than the 1930s. The first one was patented in 1907.
The Junkers predates FMs by a few years, the Jumo was flying in 1932 but FM didn't build an OP until 1938. There are quite few variants on the OP theme, some of the most exotic come from the Brits, of course.
Any engine fanatic would love to have worked for Napier, which appears to have been founded by a bunch of bored watchmakers who wished there was a way to convert oil to heat, smoke, and noise with as many parts as possible.
The Junkers predates FMs by a few years, the Jumo was flying in 1932 but FM didn't build an OP until 1938. There are quite few variants on the OP theme, some of the most exotic come from the Brits, of course.
Any engine fanatic would love to have worked for Napier, which appears to have been founded by a bunch of bored watchmakers who wished there was a way to convert oil to heat, smoke, and noise with as many parts as possible.
RickB
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Oh man, much misery and many many laughs nursing FMs through snorkeling and equalizers. It was the only engine I ever had "runaway."
There are some great sea stories based on those beasts. I couldn't find it on this computer but I have a scan someplace of a photo of a very young me sitting on the log desk trying to capture some air. It shows a good view of the inboard exhaust valve and a "coffin cover." When I have time I'll dig it out, would make a good avatar.
RickB
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There was an English company named Doxford that built those things and powered half the merchant shipping fleet for decades ... there is nothing new in the engine room, just different ways of doing the same thing.
bfloyd4445
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Marin, the engine i refered to I cant find the link to. I just discovered it a couple of days ago and thought i had saved it but cant find it. These are two0 diferent engines crrect. I cant find the links anywhere.
ok, it worked like this.each cylinder was closed at each end and each end had intake and exhaust valves. In side the cylinder there was a single piston that was the same on the top as the bottom. The center of the cylinder was slotted to allow rods to be connected to the piston sorta risk pin like for crank operation. The other engine i found that was interesting was this one http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder
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RickB
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Was it not this one?
Watch "Opposed Piston Opposed Cylinder Engine" Video at Engineering TV
It is just another Doxford to me.
bfloyd4445
Guru
Thats one of the two neat engines i found but the one I was most interested in was basically a two cylinder single piston engine. The piuston was the same on each end and the wrist pin drove the crank. This engine upon ignition it was compressing on the way down then it would ignite on the other end back and forth. Think of a single piston with a top on both the top and bottom with each end in its own cylinder.
Anyway Rick, check out this interesting link which has tons of descriptions of many diferent engine designs on the right side of the page.
Opposing piston 80% thermally efficient NASA « Dreamer3000′s Weblog
FF
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The need for really efficient multi fuel drone engines will create enough R&D ca$h to better the future of boats and noisemaker in time.
GO DARPA!
GO DARPA!
bfloyd4445
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that would be nice
FF
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The "big boys" with the large single engines pushing an oil bucket have efficiencies we can only dream of .
Just getting near existing tanker efficiency would be an improvement.
Just getting near existing tanker efficiency would be an improvement.
RickB
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In terms of BSFC, we are only about 10 percent off. Considering how inexpensive and zero maintenance our engines are, that is pretty good.
Depending on the size of engine the BSFC figures overlap even in automotive applications.
The only place you will see over 50 percent thermal efficiency is on the very large slow speed 2-stroke engines.
Depending on the size of engine the BSFC figures overlap even in automotive applications.
The only place you will see over 50 percent thermal efficiency is on the very large slow speed 2-stroke engines.
1 engine vs 2 engines
Hi Guys
For the last 30 years I have being sailing on sailboats, and because I`m moving to Fort Myers where I have an apartment with a dock included, that only accept up to 5`0 draftI So I sold my 52 Amel Supermaramu. Now I`m looking to buy a power boat, trawler, or similar. Because I`m ignorant on this matter the first question is: One Engine or two engines.Y will be concentrated in the ICW, or Bahamas.I had in mine Mainship or Grand Banks type.
Any suggestion are really welcome.
Hi Guys
For the last 30 years I have being sailing on sailboats, and because I`m moving to Fort Myers where I have an apartment with a dock included, that only accept up to 5`0 draftI So I sold my 52 Amel Supermaramu. Now I`m looking to buy a power boat, trawler, or similar. Because I`m ignorant on this matter the first question is: One Engine or two engines.Y will be concentrated in the ICW, or Bahamas.I had in mine Mainship or Grand Banks type.
Any suggestion are really welcome.
psneeld
Guru
There is no answer...only preference.
Many will lean towards 2 if venturing to very remote areas where self rescue is important.
Many will lean towards 1 if that's not important...
But ultimately...there is no right answer except the one YOU make....no matter WHO tries to convince you otherwise.
If you are totally mechanically inept...the two or more may be a better solution for you...but as in all my answers in this discussion "may" and "maybe" or "possibly" are the most frequently used words.
I've been going to sea as a pro since college in everything up to 400 footers and have owned both single and twins with around 10 yers living aboard. I am just finishing up a 2000 mile, 4 month trip on the intracoastal.
For every advantage of 2 or 1...there's a disadvantage or you could even say neither can do more (99% of the time) and neither does less. That is because every boat is different and none perfectly suited for every situation.
Only a totally custom boat might tweek out an advantage across the board...but just barely.
Many will lean towards 2 if venturing to very remote areas where self rescue is important.
Many will lean towards 1 if that's not important...
But ultimately...there is no right answer except the one YOU make....no matter WHO tries to convince you otherwise.
If you are totally mechanically inept...the two or more may be a better solution for you...but as in all my answers in this discussion "may" and "maybe" or "possibly" are the most frequently used words.
I've been going to sea as a pro since college in everything up to 400 footers and have owned both single and twins with around 10 yers living aboard. I am just finishing up a 2000 mile, 4 month trip on the intracoastal.
For every advantage of 2 or 1...there's a disadvantage or you could even say neither can do more (99% of the time) and neither does less. That is because every boat is different and none perfectly suited for every situation.
Only a totally custom boat might tweek out an advantage across the board...but just barely.
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Tom.B
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I suggest you read some of this thread first: http://www.trawlerforum.com/forums/s6/single-vs-twin-epic-thread-8067.html
jwnall
Moderator Emeritus
I agree. You still will not have an answer to your question, but at least you can read all the pros and cons without having to have them repeated.
John
RT Firefly
Enigma
Greetings,
Welcome aboard, 1 vs. 2?
Welcome aboard, 1 vs. 2?
Nomad Willy
Guru
We all understand your post RT but I'll bet the OP is wondering what all the panic is about.
Portuguese
Guru
Jorge
Welcome!
One question: In 30 years of sailing, how many events of damage engines did you have and why? Now, having in mind that you were concentrated on sailing with the wind, now that you will be concentrated in an engine and therefore you'll be giving it a lot of TLC, how many problems you'll have per year?
How many masts did your sailboat have? Were two masts a lot to look for?
I would recommend that you use your best sailing common sense and apply it in your next motorboat.
Good luck
P.
Welcome!
One question: In 30 years of sailing, how many events of damage engines did you have and why? Now, having in mind that you were concentrated on sailing with the wind, now that you will be concentrated in an engine and therefore you'll be giving it a lot of TLC, how many problems you'll have per year?
How many masts did your sailboat have? Were two masts a lot to look for?
I would recommend that you use your best sailing common sense and apply it in your next motorboat.
Good luck
P.
RT Firefly
Enigma
Greetings,
Mr. mb. I think Mr. jorge's question was answered in posts #2 & #3. IF he is able to wade through the first 200 or 300 posts he should be able to reach the logical conclusion stated by Mr. psneeld UNLESS we want to try for 800+...
Mr. mb. I think Mr. jorge's question was answered in posts #2 & #3. IF he is able to wade through the first 200 or 300 posts he should be able to reach the logical conclusion stated by Mr. psneeld UNLESS we want to try for 800+...
Cyclone
Senior Member
Having boated for over 50 years with a single and during that time only experienced three failures, a single would and still is my first choice. As stated earlier in this and other forums, maintenance is the key. Not complicated but due diligence of the owner. Treat the engine as you treat your shared captain.
The only issue re sail over power, one source of mechanical power, is that a sail boat tends not to be subjected to the same wind/current issues when docking and undocking. Many folk think that twins will minimize that issue. Not true. Being able to handle the boat requires skill that comes with practice and always an alternative plan. If the vessel you are about to acquire has a single and you are worried think about a thruster. There is a new model on the market which does not require major construction and that will take care of managing your bow especally trying to get it into the wind.
The other issue re single and twin that you do acquire double the trouble and cost. So buy what fits your needs and regardless of power practice doing the difficult things, docking, undocking especally, until they become second nature.
The only issue re sail over power, one source of mechanical power, is that a sail boat tends not to be subjected to the same wind/current issues when docking and undocking. Many folk think that twins will minimize that issue. Not true. Being able to handle the boat requires skill that comes with practice and always an alternative plan. If the vessel you are about to acquire has a single and you are worried think about a thruster. There is a new model on the market which does not require major construction and that will take care of managing your bow especally trying to get it into the wind.
The other issue re single and twin that you do acquire double the trouble and cost. So buy what fits your needs and regardless of power practice doing the difficult things, docking, undocking especally, until they become second nature.
RT Firefly
Enigma
Greetings,
And they're off - YouTube
And they're off - YouTube
RT - You Are Too Funny! This lucky OP has no concept what he has just entered by starting this thread! But, I do wish him great learning, fun, and enjoyment on TF.... Welcome Aboard!
BTW: My 10 cents!
Twins, Twins, Twins, Twins, Twins, Twins, - - > Cause I Like Em!
