The Finer Points of Ship Construction
- Thread starter Mark Chirnside
- Start date
-
- Tags
- construction
Mark Chirnside
Member
Hi Charles, Erik!
Thanks Charles for the information. I understand that reciprocating engines then are not as smooth as turbine engines (at least the engines themselves, not the propellers). But I can't seem to find anyone supporting the 'shake the ship apart' talk with regard to these engines -- I mean, there seems no reason why well-designed and balanced engines could 'shake a ship apart.'
I've also some thoughts on bulk carriers, Noel.
Best regards,
Mark.
Thanks Charles for the information. I understand that reciprocating engines then are not as smooth as turbine engines (at least the engines themselves, not the propellers). But I can't seem to find anyone supporting the 'shake the ship apart' talk with regard to these engines -- I mean, there seems no reason why well-designed and balanced engines could 'shake a ship apart.'
I've also some thoughts on bulk carriers, Noel.
Best regards,
Mark.
Mark Chirnside
Member
Hi Erik!
Who, if you don't mind is saying the ship would be shaken apart???
Daniel Allen Butler, we're on:
http://www.titanic-titanic.com/forum/ikonboard.cgi?s=3d57f777737bffff;act=ST;f=12;t=1;st=10#entry14
Just click on the blue, go to 'other ships' and then '...Olympic' folder, page 2 of the thread.
Best regards,
Mark.
Who, if you don't mind is saying the ship would be shaken apart???
Daniel Allen Butler, we're on:
http://www.titanic-titanic.com/forum/ikonboard.cgi?s=3d57f777737bffff;act=ST;f=12;t=1;st=10#entry14
Just click on the blue, go to 'other ships' and then '...Olympic' folder, page 2 of the thread.
Best regards,
Mark.
Charles B. Weeks Jr.
Member
I don't think they'd actually shake the ship apart. But they could cause pipes to break (a frequent cause of engine room fires on new Diesel ships) or other parts to fail due to the vibration. I have read accounts of the German liners, pre-Imperator that had large recips and they were noted for the vibration and the discomfort to passengers and crew alike. The scene in the engine room in Cameron's movie shows the engines very nice and quiet, and at slow speed they are. But Hooked Up they're something else.
Charlie
Charlie
Noel F. Jones
Member
Erik Wood said of myself:
"This is the second post made by him that I .... can actually partially agree with."
Let me know what the present issues are and I'll do my best to accommodate you – albeit I am definitively over-extended when it comes to theoretical naval architecture.
Charles B.Weeks Jnr.
American Export-Isbrandtsen, I notice. It's probably before your time but I'm trying to track down an informed obituary of Hans Isbrandtsen; can you help? I don't recall that New York had any dedicated shipping dailies but his passing would have been reported via the commercial if not the social desk of the NY Times or similar. I think he died in the late 1950s (but I may be doing him a disservice!).
Incidentally, my searching elicited a person of that name who was killed in the WTC and it's difficult not to conjecture he may well have been a descendant relative.
To your knowledge, is there a history of Isbrandtsen Line extant, preferably pre-merger? I'm trying to profile their antritrust agitation apropos the conference dual rate system.
I appreciate all this is a bit esoteric for ET so feel free to e-mail me with any information you can provide.
VIBRATION
From the perspective of living on top of engine rooms, I went from motorships to steam reciprocating and found the latter reassuringly peaceful. I went from them to steam turbine and found it disconcertingly quiet, unless some cavalier manoeuvreing was going on.
Vibration-wise, one knew where one was - literally - with motorships!
Noel
"This is the second post made by him that I .... can actually partially agree with."
Let me know what the present issues are and I'll do my best to accommodate you – albeit I am definitively over-extended when it comes to theoretical naval architecture.
Charles B.Weeks Jnr.
American Export-Isbrandtsen, I notice. It's probably before your time but I'm trying to track down an informed obituary of Hans Isbrandtsen; can you help? I don't recall that New York had any dedicated shipping dailies but his passing would have been reported via the commercial if not the social desk of the NY Times or similar. I think he died in the late 1950s (but I may be doing him a disservice!).
Incidentally, my searching elicited a person of that name who was killed in the WTC and it's difficult not to conjecture he may well have been a descendant relative.
To your knowledge, is there a history of Isbrandtsen Line extant, preferably pre-merger? I'm trying to profile their antritrust agitation apropos the conference dual rate system.
I appreciate all this is a bit esoteric for ET so feel free to e-mail me with any information you can provide.
VIBRATION
From the perspective of living on top of engine rooms, I went from motorships to steam reciprocating and found the latter reassuringly peaceful. I went from them to steam turbine and found it disconcertingly quiet, unless some cavalier manoeuvreing was going on.
Vibration-wise, one knew where one was - literally - with motorships!
Noel
Mark Chirnside
Member
Hi!
VIBRATION
I seem to recall the HAPAG liner Deutschland had enormous vibration at 23 knots, making much of her after accommodation uninhabitable.
In being specific to engines, I think we can be reasonably sure that most vibration comes from the propellers rather than the engines themselves, the impulses reverberating off the stern plating and progressing through the hull. While I appreciate that reciprocating engines themselves may run with a little more vibration than turbines, I personally can't see any reason either as to why that vibration can't be reduced to a reasonable level through the use of four-cylinder, properly-balanced engines.
EXPANSION JOINTS
Out of interest Noel, as the Queen Mary served for over thirty years and is still around, did she ever suffer from structural problems related to fatigue? We know her scantlings were strengthened as a result of experience with the pre-World War I liners.
Another point that I am wondering concerns the number of expansion joints: I generally thought that the more expansion joints, the better. Reviewing Olympic's, Berengaria's and Aquitania's expansion joints in 1931 the Board of Trade recommended more joints above the strength deck on future liners to distribute stresses more evenly. Indeed, when Britannic's after well deck was enclosed, Harland & Wolff added an expansion joint there. Britannic had another on the boat deck as well. But it can't be as simple as that.
Is there any recommendation for the spacing between expansion joints or anything? I mean, five may be better than three, but what about six?
QE2 & NORWAY
Regarding these liners, what is there construction as regards expansion joints and stress-relieving features? Apparently both, ships, the latter forty years old, are starting to age and suffer mechanical (i.e. plumbing) problems.
Best regards,
Mark.
VIBRATION
I seem to recall the HAPAG liner Deutschland had enormous vibration at 23 knots, making much of her after accommodation uninhabitable.
In being specific to engines, I think we can be reasonably sure that most vibration comes from the propellers rather than the engines themselves, the impulses reverberating off the stern plating and progressing through the hull. While I appreciate that reciprocating engines themselves may run with a little more vibration than turbines, I personally can't see any reason either as to why that vibration can't be reduced to a reasonable level through the use of four-cylinder, properly-balanced engines.
EXPANSION JOINTS
Out of interest Noel, as the Queen Mary served for over thirty years and is still around, did she ever suffer from structural problems related to fatigue? We know her scantlings were strengthened as a result of experience with the pre-World War I liners.
Another point that I am wondering concerns the number of expansion joints: I generally thought that the more expansion joints, the better. Reviewing Olympic's, Berengaria's and Aquitania's expansion joints in 1931 the Board of Trade recommended more joints above the strength deck on future liners to distribute stresses more evenly. Indeed, when Britannic's after well deck was enclosed, Harland & Wolff added an expansion joint there. Britannic had another on the boat deck as well. But it can't be as simple as that.
Is there any recommendation for the spacing between expansion joints or anything? I mean, five may be better than three, but what about six?
QE2 & NORWAY
Regarding these liners, what is there construction as regards expansion joints and stress-relieving features? Apparently both, ships, the latter forty years old, are starting to age and suffer mechanical (i.e. plumbing) problems.
Best regards,
Mark.
As to the Norway she was due to retire from service from the NCL fleet last year. But they decided to keep her around. She has had plant problems and her structure seems to be starting to show fatigue. Not necessarily from the sea but the additions of weight to the frames.
I would imagine that the QE2 and the Norway are very similar in construction. I will look up some info on the expansion joints.
I would imagine that the QE2 and the Norway are very similar in construction. I will look up some info on the expansion joints.
Charles B. Weeks Jr.
Member
Noel:
There is indeed such a book. "The American Viking, The Saga of Hans Isbrandtsen" I've read it and its very good, we have it in the Maine Maritime Academy Library. Hans died in 1953 of a heart attack on (Wake Is?) on his way to the orient. By the way did you know that Hans was a cousin of Arnold P. Moeller (Maersk Line)?
There is indeed such a book. "The American Viking, The Saga of Hans Isbrandtsen" I've read it and its very good, we have it in the Maine Maritime Academy Library. Hans died in 1953 of a heart attack on (Wake Is?) on his way to the orient. By the way did you know that Hans was a cousin of Arnold P. Moeller (Maersk Line)?
David G. Brown
RIP
Going back to the subject of engine vibration--The mass of moving metal in a marine steam engine was enormous. Not being an engineer, I lack the precise wording to explain this thought...but would not the momentum of that moving metal (pistons, cranks, etc.) eventually cause some sort of fatigue of the engine beds?
This thought comes to me as a result of discussions with my grandfather worked for B&O railroad. When they switched to diesel engines the tracks began holding up better. The moving metal of the connecting rods on steam locomotives was "pounding" the rails and causing the wooden sleepers to slowly crush and deteriorate.
Anyone have any thoughts along this direction?
-- David G. Brown
This thought comes to me as a result of discussions with my grandfather worked for B&O railroad. When they switched to diesel engines the tracks began holding up better. The moving metal of the connecting rods on steam locomotives was "pounding" the rails and causing the wooden sleepers to slowly crush and deteriorate.
Anyone have any thoughts along this direction?
-- David G. Brown
Adam McGuirk
Member
Speeking of engines, say Murdoch did reverse the engines like has been said many times, wouldn't that have called a great deal of momentum in the ship, which is not really mentioned by survivors?
Adam
Adam
Mark Chirnside
Member
Hi!
David wrote and Erik replied:
In Olympic's case, a number of loose rivets were noted in her thrust blocks in 1932 (I understand these blocks were part of the bedplates), but the tank top and double bottom were sound. These were replaced and re-amered at boiler construction standard. In order to reduce the fatigue created, changes were made to Britannic's engines, by fitting a nineth balance weight and reinforcing structural members. In Olympic's case, in 1932 new balance weights were fitted with new crankshafts and other changes were made to reduce the load on the top half of the main bearings by more than one third; after this work, not the slighest engine defect was ever discovered. With proper balancing and design, I can't see why engines could not work relatively well without causing other damage to a ship's structure.
I can't help thinking that it might have been better to complete such changes at the 1920 refitting, because Harland & Wolff had clearly modified Britannic's engines as early as 1914, but with Olympic they just added inadequate strenghening plates in 1911, which served until 1932.
Ismay testified that the engines were 'balanced, to run their best at 78 r.p.m.' but I am not quite sure what me meant, although this speed was the finest in terms of being the smoothest vibration-free speed combined with speed performance and fuel economy (if you get my explanation!)
I look forward to that expansion joint material Erik.
Best regards,
Mark.
David wrote and Erik replied:
In Olympic's case, a number of loose rivets were noted in her thrust blocks in 1932 (I understand these blocks were part of the bedplates), but the tank top and double bottom were sound. These were replaced and re-amered at boiler construction standard. In order to reduce the fatigue created, changes were made to Britannic's engines, by fitting a nineth balance weight and reinforcing structural members. In Olympic's case, in 1932 new balance weights were fitted with new crankshafts and other changes were made to reduce the load on the top half of the main bearings by more than one third; after this work, not the slighest engine defect was ever discovered. With proper balancing and design, I can't see why engines could not work relatively well without causing other damage to a ship's structure.
I can't help thinking that it might have been better to complete such changes at the 1920 refitting, because Harland & Wolff had clearly modified Britannic's engines as early as 1914, but with Olympic they just added inadequate strenghening plates in 1911, which served until 1932.
Ismay testified that the engines were 'balanced, to run their best at 78 r.p.m.' but I am not quite sure what me meant, although this speed was the finest in terms of being the smoothest vibration-free speed combined with speed performance and fuel economy (if you get my explanation!)
I look forward to that expansion joint material Erik.
Best regards,
Mark.
John Meeks
Guest
My knowledge on these matters is relatively limited, since, on a day to day basis, I deal with statics rather than dynamics - I leave that more complicated stuff to you guys!
However - one small point that may (or may not!) be appropriate...
Whilst any reciprocating engine will always produce some vibration (which can hammer the bejesus out of mounting bed!) - a well designed, carefully run power unit can be set to run at an appropriate speed to limit this vibration to within quite acceptable parameters, as has been pointed out.
But when you are considering more than one engine, you can have the added effect of synchronisation and harmonic resonance to deal with. This can be a particularly delicate 'balancing act' on large multi-engined aircraft with reciprocating engines.
Indeed, one or two examples spring to mind (particularly one or two German WWII twin, and tri-motor bombers) where it was normal practise to ensure that the motors were running 'out of synch.' to avoid a harmonic resonance cycle being established.
Such a cycle (where, at periodic intervals, one cylinder on one engine 'fires' at exactly the same moment as a cylinder on a second power unit) can produce a substantial hammering to the structure of any aircraft or vessel - not to mention being damned irritating to everyone on board!
Just a thought....
John M
However - one small point that may (or may not!) be appropriate...
Whilst any reciprocating engine will always produce some vibration (which can hammer the bejesus out of mounting bed!) - a well designed, carefully run power unit can be set to run at an appropriate speed to limit this vibration to within quite acceptable parameters, as has been pointed out.
But when you are considering more than one engine, you can have the added effect of synchronisation and harmonic resonance to deal with. This can be a particularly delicate 'balancing act' on large multi-engined aircraft with reciprocating engines.
Indeed, one or two examples spring to mind (particularly one or two German WWII twin, and tri-motor bombers) where it was normal practise to ensure that the motors were running 'out of synch.' to avoid a harmonic resonance cycle being established.
Such a cycle (where, at periodic intervals, one cylinder on one engine 'fires' at exactly the same moment as a cylinder on a second power unit) can produce a substantial hammering to the structure of any aircraft or vessel - not to mention being damned irritating to everyone on board!
Just a thought....
John M
