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Titanic
My wife watched Titanic the other night, I sat down for the 'crash'
scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? -- Scott Vernon Plowville Pa _/)__/)_/)_ |
My wife watched Titanic the other night, I sat down for the 'crash'
scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? Poor Scotty Potti is soooo ignorant that he doesn't know that ship wheels worked like tillers on ships until late 20's and early 30's, then were slowly converted to "car logic." In other words, turn the wheel left to go right. RB |
Scotty wrote...
and why is the ship in color? Wasn't everything black and white at that time? |
Scott Vernon wrote:
My wife watched Titanic the other night, I sat down for the 'crash' scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? Yes, it was quite a little controversy and some people will still argue about it. It used to be common for the watch officer or pilot to give helm orders in terms of a tiller... ie, to turn starboard, they'd order the helmsman "put the helm to port." and vice versa. That way, it was up to the helmsman to know how his helm worked, not the officer. A pilot could step aboard any ship using a tiller, wheel, whipstaff, shin-cracker, or whatever, and bring her safely in. Somewhere around World War 1, people noticed that no ships had tillers any more. So they changed the standard terms. the Royal Navy held on to "reverse helm orders" until the early 1930s, most everybody else changed about 10 ~ 15 years sooner. So, when 2nd Officer Murdoch received the report of an iceberg right ahead (and the odds are good he saw it himself about the same time), he ordered the boatswain's mate of the watch (who survived BTW, a man named Hitchins) to put the helm "hard a-starboard" in order to put the ship to port. Then as the ship started swinging, Murdoch ordered the helm put the other way in order to swing the stern out away from the iceberg. They almost made it. Regards Doug King |
It used to be common for the watch officer or pilot to give helm orders
in terms of a tiller... ie, to turn starboard, they'd order the helmsman "put the helm to port." and vice versa. Good god. WRONG!!!! Titanic's wheel worked counter to today's wheels. Tiller logic prevailed for quite a few years, even with wheels on large ships. The wheel on Titanic had to be turned to PORT for a starboard course. RB |
OH! Thanks Doug.
SV "DSK" wrote in message . .. Scott Vernon wrote: My wife watched Titanic the other night, I sat down for the 'crash' scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? Yes, it was quite a little controversy and some people will still argue about it. It used to be common for the watch officer or pilot to give helm orders in terms of a tiller... ie, to turn starboard, they'd order the helmsman "put the helm to port." and vice versa. That way, it was up to the helmsman to know how his helm worked, not the officer. A pilot could step aboard any ship using a tiller, wheel, whipstaff, shin-cracker, or whatever, and bring her safely in. Somewhere around World War 1, people noticed that no ships had tillers any more. So they changed the standard terms. the Royal Navy held on to "reverse helm orders" until the early 1930s, most everybody else changed about 10 ~ 15 years sooner. So, when 2nd Officer Murdoch received the report of an iceberg right ahead (and the odds are good he saw it himself about the same time), he ordered the boatswain's mate of the watch (who survived BTW, a man named Hitchins) to put the helm "hard a-starboard" in order to put the ship to port. Then as the ship started swinging, Murdoch ordered the helm put the other way in order to swing the stern out away from the iceberg. They almost made it. Regards Doug King |
Doug was correct about the wheel. I was wrong. Scotty Potti is still an idiot. RB |
Bobsprit wrote:
Good god. WRONG!!!! Titanic's wheel worked counter to today's wheels. No, it did not. You are misinformed. ... Tiller logic prevailed for quite a few years, even with wheels on large ships. The wheel on Titanic had to be turned to PORT for a starboard course. That's a misconception. Does the USS Constitution wheel work backwards? How about all theose skipjacks from the 1890s and early 1900s? For that matter, the diagrams of the Titanic's steering system (provided by Brown & Co, Marine Engineering & Hydraulics) are still on file at Harlan & Wolff's, the shipbuilder. Several writers from Darcy Lever, Esq ('Young Sea Officer's Sheet Anchor, 1819') to Allan Villiers have documented how ships wheels worked. Not one case of a "tiller rigged" wheel is known to have existed. If you get a copy of Joshua Slocum's "Voyage Alone Around The World" he includes a diagram of his steering rig. Guess which way the wheel turned... DSK |
Doug was correct about the wheel.
I was wrong. As usual. S/V Express 30 "Ringmaster" "Trains are a winter sport" |
In article ,
SAIL LOCO wrote: Doug was correct about the wheel. I was wrong. As usual. At least he stood up and admitted it.... something your hero Bush refuses to do. -- Jonathan Ganz (j gan z @ $ail no w.c=o=m) http://www.sailnow.com "If there's no wind, row." |
"DSK" wrote If you get a copy of Joshua Slocum's "Voyage Alone Around The World" he includes a diagram of his steering rig. Guess which way the wheel turned... Clockwise? |
On Wed, 22 Sep 2004 07:43:27 -0400, "Scott Vernon"
wrote this crap: My wife watched Titanic the other night, I sat down for the 'crash' scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? No. That's what happened. Pathetic Earthlings! No one can save you now! |
OzOne wrote: On 22 Sep 2004 12:31:15 GMT, (Bobsprit) scribbled thusly: Doug was correct about the wheel. I was wrong. RB Hey Bubbles, I think you can regard this as a milestone. It's a milestone for Dig too. Cheers |
The sad part about this observation is that, if true, they might not
have lost the ship if the turn had continued. By turning back in course the iceberg was able to breach the hull along many watertight sections. If I remember correctly, she was designed to survive three sections flooding but not more. Cheers DSK wrote: Scott Vernon wrote: My wife watched Titanic the other night, I sat down for the 'crash' scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? Yes, it was quite a little controversy and some people will still argue about it. It used to be common for the watch officer or pilot to give helm orders in terms of a tiller... ie, to turn starboard, they'd order the helmsman "put the helm to port." and vice versa. That way, it was up to the helmsman to know how his helm worked, not the officer. A pilot could step aboard any ship using a tiller, wheel, whipstaff, shin-cracker, or whatever, and bring her safely in. Somewhere around World War 1, people noticed that no ships had tillers any more. So they changed the standard terms. the Royal Navy held on to "reverse helm orders" until the early 1930s, most everybody else changed about 10 ~ 15 years sooner. So, when 2nd Officer Murdoch received the report of an iceberg right ahead (and the odds are good he saw it himself about the same time), he ordered the boatswain's mate of the watch (who survived BTW, a man named Hitchins) to put the helm "hard a-starboard" in order to put the ship to port. Then as the ship started swinging, Murdoch ordered the helm put the other way in order to swing the stern out away from the iceberg. They almost made it. Regards Doug King |
DSK wrote: So, when 2nd Officer Murdoch received the report of an iceberg right ahead (and the odds are good he saw it himself about the same time), he ordered the boatswain's mate of the watch (who survived BTW, a man named Hitchins) to put the helm "hard a-starboard" in order to put the ship to port. Then as the ship started swinging, Murdoch ordered the helm put the other way in order to swing the stern out away from the iceberg. Doug, apparently he did not reverse the order. See: http://www.encyclopedia-titanica.org...an_collins.pdf It would seem that reversing the engines to full power would have been a mistake that would have reduced rudder effectiveness. Cheers |
Nav wrote: DSK wrote: So, when 2nd Officer Murdoch received the report of an iceberg right ahead (and the odds are good he saw it himself about the same time), he ordered the boatswain's mate of the watch (who survived BTW, a man named Hitchins) to put the helm "hard a-starboard" in order to put the ship to port. Then as the ship started swinging, Murdoch ordered the helm put the other way in order to swing the stern out away from the iceberg. Doug, apparently he did not reverse the order. See: http://www.encyclopedia-titanica.org...an_collins.pdf It would seem that reversing the engines to full power would have been a mistake that would have reduced rudder effectiveness. Cheers Coupla points: 1. When he shifted the rudder, from (new world) hard port to hard stbd, the ship would continue to swing to port for a time before starting to swing to stbd. It's a matter of timing and conjecture as to whether his was right or wrong. 2. Putting the engines astern on a ship that is running full speed, is not the fastest of processes, so he probably still had good steering power ... i.e., doubt they got the engines stopped and started astern prior to collision. |
Nav wrote:
Doug, apparently he did not reverse the order. See: http://www.encyclopedia-titanica.org...an_collins.pdf Encyclopedia Titanica is a great web site. If you poke around, you'll find a couple of contributions I've made to it. As for whether Murdoch did or did not order the helm reversed: the above cited article is taken solely from the Inquiries, which came to several notably (possibly deliberately?) erroneous conclusions. Hichins would be in a position to know, so there's no point in arguing with him... although it should be noted that he made several mistakes in his testimony. BTW the oft-quoted estimate of 37 seconds is based on Hichins testimony that the Titanic had turned "about" 2 points before hitting the berg. The U.S. Inquiry made underway tests with the RMS Olympic to determine the time & distance this would have taken, and this is the origin of that figure. Its accuracy is a very open question. It would seem that reversing the engines to full power would have been a mistake that would have reduced rudder effectiveness. Funny they should say that, and it is corrected in another article on that same web site. More below. Cheers otnmbrd wrote: Coupla points: 1. When he shifted the rudder, from (new world) hard port to hard stbd, the ship would continue to swing to port for a time before starting to swing to stbd. It's a matter of timing and conjecture as to whether his was right or wrong. Yes, the ship was almost 900' long and 70,000 tons of mass. Not going to stop on a dime; nor turn on one. It would also take the steering engine some seconds to put the rudder from hard over one way to hard over the other. Certainly if the ship had maintained a turn to port throughout the collision, the impact area along the hull would have been longer. 2. Putting the engines astern on a ship that is running full speed, is not the fastest of processes, so he probably still had good steering power ... i.e., doubt they got the engines stopped and started astern prior to collision. Here is where things get tricky- the Titanic and her sister ships had a rather unusual engine arrangement. She had triple screws, the outboard ones driven by big reciprocating engines (in fact, the largest ever built). Her central prop was driven by the exhaust from these engines into a big turbine which was not reversible. The recips had a valve train lever to shift into reverse very quickly, which was linked to a set of valves bypassing the central turbine. So if the Titanic was ordered astern (another seperate issue... the few survivors among the engineroom & boiler room crew gave testimony that she was not reversed), the central engine would have freewheeled and not affected the rudder. It is also very likely that if the order was given to go astern, that it could not have been effectively engaged in reverse in the short time before impact. For people interested in the matter, there is a very large amount of good info available on the web. Regards Doug King |
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"Scott Vernon" wrote in message ...
My wife watched Titanic the other night, I sat down for the 'crash' scene. When they spotted the ice cube, they yelled 'hard to starboard, but it looked to me like they turned the wheel to port. Then the order 'hard to port' was given and , to me, they turned to 'the right'. Anybody else notice this? Should I quit drinking? Just Hollywoods average idiots at work. It was a Flik Flub. I noticed it to. Joe |
Joe wrote:
Bull Feathers! When the conning officer says hard to Starboard...He wants the ship to turn hard to starboard. That is true now, and has been since some time around 1910 in the U.S. There is no wheeled ship in the world that ever set op the helm ass backwards. That would be confusing and dangerious. This is an issue of some contention among old time boat enthusiasts. I've heard a lot of people, inclduing a few that knew a lot about maritime history, say that backwards steering used to be fairly common. However I don't think it was ever "the standard" and I don't think that it's the reason for "reverse helm orders." For one thing, there are too many boats & ships surviving from that time period with their steering intact. For example, Edson has been in business for a long time and they never made any "reverse" or "tiller-order" steering mechanisms. OTOH who knows wether some crusty old geezers rigged their wheels to steer like a tiller because they liked it that way. DSK |
Are you saying that the rudder effrectiveness is not reduced if the
engine is stopped? Cheers DSK wrote: |
On an old cornish working boat I sailed you had the wheel behind you.
Even on that boat the wheel turned the head normally. Cheers DSK wrote: Joe wrote: Bull Feathers! When the conning officer says hard to Starboard...He wants the ship to turn hard to starboard. That is true now, and has been since some time around 1910 in the U.S. There is no wheeled ship in the world that ever set op the helm ass backwards. That would be confusing and dangerious. This is an issue of some contention among old time boat enthusiasts. I've heard a lot of people, inclduing a few that knew a lot about maritime history, say that backwards steering used to be fairly common. However I don't think it was ever "the standard" and I don't think that it's the reason for "reverse helm orders." For one thing, there are too many boats & ships surviving from that time period with their steering intact. For example, Edson has been in business for a long time and they never made any "reverse" or "tiller-order" steering mechanisms. OTOH who knows wether some crusty old geezers rigged their wheels to steer like a tiller because they liked it that way. DSK |
Nav wrote:
Are you saying that the rudder effrectiveness is not reduced if the engine is stopped? I'm saying that many of the statements made about why the Titanic hit the iceberg, with regard to her rudder's ineffectiveness, are incorrect. As for "engine stopped" that is not a very useful terminology... you mean shaft stopped & locked? Applying throttle in reverse? Spinning in reverse with forward way on? *If* the Titanic's central shaft had been either stopped & locked, or spinning in reverse with forward way on, then of course her rudders effectiveness would have been reduced. However neither of those cases apply for several reasons, the main one being that her central shaft had no reverse and could not have been stopped & locked. Regards Doug King |
"Nav" wrote ... For example, the order "port 20" did not mean turn the ship to port 20 degrees. What did it mean? SV |
DSK wrote: Nav wrote: Are you saying that the rudder effrectiveness is not reduced if the engine is stopped? I'm saying that many of the statements made about why the Titanic hit the iceberg, with regard to her rudder's ineffectiveness, are incorrect. Such as? As for "engine stopped" that is not a very useful terminology... you mean shaft stopped & locked? Applying throttle in reverse? Spinning in reverse with forward way on? *If* the Titanic's central shaft had been either stopped & locked, or spinning in reverse with forward way on, then of course her rudders effectiveness would have been reduced. However neither of those cases apply for several reasons, the main one being that her central shaft had no reverse and could not have been stopped & locked. If the engine were stopped the rudder effectiveness would have been reduced. I think that is most likely true, why do you disagree with it? If it were reversed, effectiveness would be even lower. Cheers |
I'm saying that many of the statements made about why the Titanic hit
the iceberg, with regard to her rudder's ineffectiveness, are incorrect. Nav wrote: Such as? Such as yours. If the engine were stopped the rudder effectiveness would have been reduced. OK, tell us what you mean by stopped. Then tell us about the Titanic's engineering plant and how they would have "stopped" the central shaft. ... I think that is most likely true, why do you disagree with it? Oh, just a silly whim on my part, no doubt. Years of marine propulsion engineering have nothing to do with it. If it were reversed, effectiveness would be even lower. That's a mighty big "if." As above, please explain how they would have put the central shaft in reverse. In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. DSK |
DSK wrote: I'm saying that many of the statements made about why the Titanic hit the iceberg, with regard to her rudder's ineffectiveness, are incorrect. Nav wrote: Such as? Such as yours. If the engine were stopped the rudder effectiveness would have been reduced. OK, tell us what you mean by stopped. Then tell us about the Titanic's engineering plant and how they would have "stopped" the central shaft. The engine would be stopped by opening the steam bypass valve. That might not stop the propellor but that's not the issue here. Now are you still saying that stopping the engine has no effect on rudder effectiveness ... I think that is most likely true, why do you disagree with it? Oh, just a silly whim on my part, no doubt. Years of marine propulsion engineering have nothing to do with it. So you think an engine in neutral has no effect on rudder? If it were reversed, effectiveness would be even lower. That's a mighty big "if." As above, please explain how they would have put the central shaft in reverse. In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. Do you know what slip is and how it would affect the rudder? What would have been a likely value of slip for the central propellor of the Titanic at full speed? It's strange but every time I've taken the helm of a displacement boat the loss of helm authority when the engine is throttled back has been most obvious. Perhaps it's your engineering expertise that makes the difference. Cheers |
OK, tell us what you mean by stopped. Then tell us about the Titanic's
engineering plant and how they would have "stopped" the central shaft. Nav wrote: The engine would be stopped by opening the steam bypass valve. That might not stop the propellor but that's not the issue here. Please tell me what ships you've steamed where the engine could be stopped by "opening a steam bypass valve." Also please tell me where the steam is bypassed to... are you suggesting dumping main steam directly into the condenser? Another point I'd like you to explain is how do you stop the engine and not the shaft. Push in the clutch, maybe? Now are you still saying that stopping the engine has no effect on rudder effectiveness No, I'm saying that 1- a ship running at full speed is not going to stop & lock the shaft in less than a minute, 2- if it did then the water flow over the rudder would still be quite strong (ie 20+ knots), 3- in the specific case of the Titanic, the central prop had no reverse and thus no way to stop the shaft. Did you pay any attention at all to my post explaining some of the basics of the Olympic class ships propulsion plant? Do you know what slip is Yes. ... and how it would affect the rudder? Sure. Is it supposed to be rocket science? Are you insisting that a ship going 20+ knots is suddenly not going to answer her helm because of the loss of the prop stream? It has been suggested that if the Titanic's central prop had been spun in reverse, the cavitation would have greatly diminished her steering response... now that is a stronger case, except that it's simply not possible when there's no reverse on the central engine. ... What would have been a likely value of slip for the central propellor of the Titanic at full speed? I don't know, but it wouldn't be hard to figure out. The stats for the engine's RPM and prop pitch are public. It's strange but every time I've taken the helm of a displacement boat the loss of helm authority when the engine is throttled back has been most obvious. Yes, and I'm sure you have lots and lots of experience driving 800+ ships at 20+ knots. They handle *very* differently than a sailboat with under auxiliary power. If you're claiming that a vessel cannot be steered without a prop stream over the rudder, then how do you manage to control your boat's heading when under sail? .... Perhaps it's your engineering expertise that makes the difference. Perhaps. DSK |
We are talking about the central shaft OZ. Please keep up.
Cheers OzOne wrote: On Thu, 30 Sep 2004 11:03:22 +1200, Nav scribbled thusly: The engine would be stopped by opening the steam bypass valve. That might not stop the propellor but that's not the issue here. Now are you still saying that stopping the engine has no effect on rudder effectiveness Hey now that would depend on which one of the three was stopped. Oz1...of the 3 twins. I welcome you to crackerbox palace,We've been expecting you. |
Nav wrote:
We are talking about the central shaft OZ. Please keep up. Actually, I think he's gotten the point more quickly than you seem to be catching on. DSK |
DSK wrote
In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. DSK I agree 100%. But if a full astern bell was rung then the induced wheel walk could of forced her stern to swing faster into the berg. Joe |
DSK wrote: OK, tell us what you mean by stopped. Then tell us about the Titanic's engineering plant and how they would have "stopped" the central shaft. Nav wrote: The engine would be stopped by opening the steam bypass valve. That might not stop the propellor but that's not the issue here. Please tell me what ships you've steamed where the engine could be stopped by "opening a steam bypass valve." Also please tell me where the steam is bypassed to... are you suggesting dumping main steam directly into the condenser? On the Titanic the turbine received LP steam from the main engines. To stop it separate from the main engines, a valve which I call a "steam bypass valve" was opened to bypass the turbine and allow the LP steam back to the condenser. It is strange that you claimed such expertise on the Titanic machinery but did not know this. Cheers |
DSK the marine propulsion expert wrote: In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. http://www.dellamente.com/titanic/engines5.htm "Regardless, most scenarios agree steam to the turbine would have been cut off. While this had little effect on the ship's forward motion, it deprived the rudder of the steady, forceful stream of water necessary to turn a ship of that size. Several sources claim the rudder on the Titanic and her sister ships was too small. If that was indeed the case, shutting down the center turbine would be the last thing you would want to do in an emergency." Hmm, seems to agree with me? My yacht steers well without propwash because it's rudder, in comparison, is huge... My point is that, most power vessels can have much smaller rudders because they use the propwash to significantly increase rudder effectiveness. It's standard naval architecture. Cheers |
DSK the marine propulsion expert wrote:
In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. Nav wrote: http://www.dellamente.com/titanic/engines5.htm Interesting web site. Thanks for the link. It does contain a number of inaccuracies, though. "Regardless, most scenarios agree steam to the turbine would have been cut off. While this had little effect on the ship's forward motion, ??? The central turbine was about 35% ~ 40% of the ships forward power. How is it going to have "little effect on the ship's forward motion?" Or do they mean that shutting off steam to the turbine would not have produced significant stopping impulse? That would be much more correct. They also don't appear to know how the reciprocating engines were reversed. ... it deprived the rudder of the steady, forceful stream of water necessary to turn a ship of that size. ??? A steady stream of water goin 22 + knots is not "forceful"? ... Several sources claim the rudder on the Titanic and her sister ships was too small. If that was indeed the case, shutting down the center turbine would be the last thing you would want to do in an emergency." The "rudder too small" claim is total malarkey. The Olympic was the same design and had a long service career, with a reputation of being a good handling ship. Hmm, seems to agree with me? Sure. It's incorrect and based on assumptions when accurate data is readily available. Speaking of which, have you worked out the prop slip for the Olympic class ships yet? Data readily available, all you need is the prop pitch, top speed, and top speed rpm. ... My yacht steers well without propwash because it's rudder, in comparison, is huge... My point is that, most power vessels can have much smaller rudders because they use the propwash to significantly increase rudder effectiveness. It's standard naval architecture. At low speed, sure. At full speed, the prop stream does increase rudder effectiveness but I'd say that it's not "significant." Judgement call, I guess... certainly your vast experience in handling large steam ships and your claimed naval architect training give you a big advantage here. DSK |
Please tell me what ships you've steamed where the engine could be stopped by "opening a steam bypass valve." Also please tell me where the steam is bypassed to... are you suggesting dumping main steam directly into the condenser? Nav wrote: On the Titanic the turbine received LP steam from the main engines. Duh. I told you that several posts ago, Navjax. .... To stop it separate from the main engines, a valve which I call a "steam bypass valve" was opened to bypass the turbine and allow the LP steam back to the condenser. The inlet to the central turbine was actually under a slight vacuum. It wouldn't be "LP steam" it was exhaust from the wing engines. And in order to *stop* the central turbine, it's steam inlet would have to be shut. Then what happens? hint- consider the relationship between the seawater inlet temp to the condenser (termed "injection") and the condensing pressure of steam going into the condenser. It is strange that you claimed such expertise on the Titanic machinery but did not know this. Strange that you are now repeating my posts, ignoring proper terminology, and basically showing total ignorance of steam propulsion engineering, while insisting that somehow I'm the one that's wrong. Actually, it's more funny than strange, and also par for the course. DSK |
Some comments interspersed
DSK wrote: DSK the marine propulsion expert wrote: In any case, the ship was going full speed, the loss of the prop stream across the rudder would not reduce the rudder's effectiveness very much. This is probably most notable, in my experience, with variable pitch props, but you can and will experience it with fixed pitch. You slow the rpm of the prop and it tends to mess a bit with the smooth flow of water past the rudder, reducing effectiveness until hull speed reduces to rpm speed. (personal observation). Nav wrote: http://www.dellamente.com/titanic/engines5.htm Interesting web site. Thanks for the link. It does contain a number of inaccuracies, though. "Regardless, most scenarios agree steam to the turbine would have been cut off. While this had little effect on the ship's forward motion, ??? The central turbine was about 35% ~ 40% of the ships forward power. How is it going to have "little effect on the ship's forward motion?" Or do they mean that shutting off steam to the turbine would not have produced significant stopping impulse? That would be much more correct. They might be thinking that the mass of the ship will keep things moving with a gradual reduction in speed, not readily apparent in the time frame of this collision. They also don't appear to know how the reciprocating engines were reversed. ... it deprived the rudder of the steady, forceful stream of water necessary to turn a ship of that size. ??? A steady stream of water goin 22 + knots is not "forceful"? It's forceful, but definitely not as forceful ... Several sources claim the rudder on the Titanic and her sister ships was too small. If that was indeed the case, shutting down the center turbine would be the last thing you would want to do in an emergency." The "rudder too small" claim is total malarkey. The Olympic was the same design and had a long service career, with a reputation of being a good handling ship. Disagree. Rudder technology has come a long way. Although I don't doubt that the ships may have been considered good handling by many of the day, there are many possibilities which could have improved the "overall" rudder effectiveness, though whether this could have saved the day, is pure conjecture. Hmm, seems to agree with me? Sure. It's incorrect and based on assumptions when accurate data is readily available. Speaking of which, have you worked out the prop slip for the Olympic class ships yet? Data readily available, all you need is the prop pitch, top speed, and top speed rpm. Slip is a variable ..... changes from day to day, based on a number of factors. ... My yacht steers well without propwash because it's rudder, in comparison, is huge... My point is that, most power vessels can have much smaller rudders because they use the propwash to significantly increase rudder effectiveness. It's standard naval architecture. At low speed, sure. At full speed, the prop stream does increase rudder effectiveness but I'd say that it's not "significant." Judgement call, I guess... certainly your vast experience in handling large steam ships and your claimed naval architect training give you a big advantage here. DSK Would disagree. Prop wash is a very important contributor to rudder effectiveness at all speeds .... put a ship's engine on "stop" .... trust me, your effectiveness decreases rapidly. otn |
.... At full speed, the prop stream does increase
rudder effectiveness but I'd say that it's not "significant." otnmbrd wrote: Would disagree. Prop wash is a very important contributor to rudder effectiveness at all speeds .... put a ship's engine on "stop" .... trust me, your effectiveness decreases rapidly. How about when letting the prop freewheel from full speed? DSK |
DSK wrote: .... At full speed, the prop stream does increase rudder effectiveness but I'd say that it's not "significant." otnmbrd wrote: Would disagree. Prop wash is a very important contributor to rudder effectiveness at all speeds .... put a ship's engine on "stop" .... trust me, your effectiveness decreases rapidly. How about when letting the prop freewheel from full speed? DSK Tough question and I don't think there's any ONE right answer. In the case of the Titanic at the time frame between sighting and collision..... IF they had started to reduce steam to the turbine prior to reversing the recips, this measured reduction while the other engines were going full, would/should have created a "disturbance" aft of that center prop which would/should have reduced the effectiveness of that single, center rudder. Now, since I can see another route to your question. If the ship was steaming along (different scenario) at full speed with no steam to the turbine (it's just "freewheeling") would this reduce effectiveness of the rudder? I would have to say yes, as it becomes a rotating drag which , in my opinion, has to create disturbed water aft of the prop, which has to disturb the "smooth" flow of water across the rudder. Without specific test which address the many various conditions and actions that where or would occur, you have to assume that the above is speculation on my part based on my own sense of what has happened when handling one or two ships. G I.E., I don't guarantee I'm right....these are my observations. otn |
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