Design ElementsTitanic


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Steve Kiger

Guest
Can anyone tell me if the design of the hydraulic helm (within the wheelhouse) had a force-feedback, or other means of determining actual rudder response to turning commands? What photos and information I have is inconclusive.

SteveK
 
Dec 4, 2000
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Steve -- I have not been able to study an exact duplicate of Titanic's system. However, I have looked closely at a contemporary system very similar produced by a competitor.

Hydraulic systems have no "feedback" such as you get when driving a car. However, this is not a disadvantage because the wheel was not turning the rudder. It was simply giving "commands" to a steering engine and that engine actually moved the rudder.

When the QM turned the steering wheel, a hydraulic cylinder in the telemotor caused a slave cylinder to move at the steering engine. This, moved the steam valves on the engine which responded by moving the rudder.

In Titanic's day water and glycerin were the hydraulic fluid. It was critical to keep the system warm so that the fluid would not freeze.

A small double-acting, single-stroke pump at the telemotor kept the hydraulic system full of fluid. This pump "clicked" when the steering wheel was at dead center (zero rudder angle). Because of the nature of hydraulic systems, however, the rudder might not have been dead center. So, a spring-loaded centering device was built into the steering engine. If the QM left the wheel at dead center, the steering engine would automatically center the rudder. This kept the wheel and rudder in synch.

Hydraulic systems "slip." Unless some synchronizing system is included, the king spoke indicating zero rudder angle will not come back to its upright position after each turn. That is why the spring-loaded system was necessary. Otherwise, any mechanical rudder angle indicator (such as is normally built into the steering pedestal) would never read correctly.

I have not determined if Titanic's pedestal had a mechanical rudder angle indicator. The ship was equipped with electrical devices to perform this function. If the QM had both, he could have compared the angle he called for against the actual position of the rudder. This would have allowed him to gauge the "lag" between the turning of the wheel and the movements of the steering engine.

The electrical rudder angle indicator (or, rudder position indicator) is plainly visible in the photo of Olympic's bridge. It is located near the deckhead in what appears to be quite an inconvenient spot.

Many people erroneously believe the spring-loaded centering system would have caused the ship to return to a straight course if the QM let go of the wheel. This is not the case, nor would it be desirable. Unlike a car, ships often require some small angle of rudder to maintain a straight course. "Fighting" an automatically-returning wheel would cause undue strain on the QM and result in an erratic course.

--David G. Brown
 
Jul 10, 2005
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Dear Captain Brown,

Where does one find such information?? I have read many books and articles on Titanic, but not how she functioned mechancially. I am finding this rather fascinating.

Thank you

Beverly
 
Dec 4, 2000
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Beverly -- One night in the pilot house I got to talking about why the ancient Greek sailors greased their pants. One of the other fellows stopped me. "Dave," he said. "You know too much."

You can study the telemotor in a dockside restaurant in Toronto. I don't have the name in front of me, but it is behind a small maritime museum and specializes in fish. The telemotor is on the second floor surrounded by potted palms.

If you want to study a steering engine, I suggest the museum ship Willis B. Boyer in Toledo, Ohio. The steam-powered steering engine on this ship dates from 1911, so is contemporaneous with Titanic. Although smaller, it functions on the same concept: moving the steering wheel changes the control valves on the two pistons. The pistons then run in the appropriate direction until the engine has moved the rudder far enough to reach a "neutral" position of the valving.

My personal riverboat has hydraulic steering, so I know well its benefits and drawbacks.

Oh yes...the Greeks greased their pants so they could slide on their rowing benches. Special short pants were employed as the world's first sliding-seat rowing.

-- David G. Brown
 
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Steve Kiger

Guest
Thank you for the informative response. I was curious--in the theoretical sense--of whether or not the Quartermaster would know if he had lost rudder response due to a failure of the hydraulic system or the steering engine. What pictures I have--downloads mainly--suggest a half-circle display arranged above the top edge of the helm. Is this perhaps the rudder angle indicator you mentioned?
 
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Steve -- Any breakdown of a hydraulic system should be immediately apparent by the "feel" of the steering wheel. Just what a 1912-era telemotor would feel like, though, I don't know because I've not used one.

On one ferry that I ran a few years ago the master hydraulic pump leaked. If we did not fill it every morning, we would discover that it took more and more turns of the steering wheel to obtain the same rudder angle. With a full reservoir, there were 8 turns "lock to lock." After two days of innatention, you could crank 40 turns without ever getting hard over in either direction. Needless to say, we replaced the leaking bearing.

The loss of the steering engine would not be "felt" by the QM. He would note quickly, however, that the ship was not responding to the helm. This would be obvious even at night in the enclosed wheelhouse because the compass reading would not change, or would change in the wrong direction.

I'm not sure about the half-circle display you mentioned. The electric rudder angle/position indicator on Olympic's bridge looks like any large electric meter of the period. In fact, the guts inside were probably identical to the meters on the electrical switchboard. The only difference was the face, which on the rudder indicator was graduated in degrees left or right of center.

The mechanical rudder angle/position indicator on the telemotor that I have studied is a half-circle graduated in degrees left and right from center. A large bronze pointer shows the amount of helm applied. This pointer is driven mechanically through gearing from the steering wheel shaft.

Keep in mind that the indicator on the telemotor does not really say anything about the rudder. It only indicates the amount of helm that has been called for by the QM turning the wheel. That is why the electrical indicator was needed, to provide the true rudder angle.

On the subject of failure -- both the wheelhouse wheel and the auxiliary steering wheel on the bridge would have been incapacitated by a failure of the hydraulic system. Steering would have been shifted to the so-called "docking bridge." In the unlikely event that both steering engines should fail, the rudder could have been controlled by by block and tackle.

More than likely, however, if the both steering engines had failed at sea, the rudder would have been secured amidships. Titanic could have been "aimed" sufficiently well to make New York by using only its reciprocating engines. If the port engine were run slower than the starboard, the ship would turn left. The reverse would be true if the starboard engine were slowed. About two weeks ago I talked to a German captain who brought his ship into harbor using this technique.

-- David G. Brown
 
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Steve Kiger

Guest
Thank you once again. My general impressions, based on my own experience with hydraulics in the military, suggested much the same, but having a ship-driver's views are much appreciated. Glad to know I'm at least thinking in the right direction on how the systems operated.
 

Cal Haines

Member
Dec 2, 2000
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Tucson, AZ USA
Dave wrote:
Many people erroneously believe the spring-loaded centering system would have caused the ship to return to a straight course if the QM let go of the wheel. This is not the case, nor would it be desirable. ...

Hi Dave,

The receiving telemotor worked against two large springs that tried to force it to center. It is my understanding that if the helmsman released the wheel it would, in fact, return to center. I can post a diagram if you like. The helmsman would feel the pressure of the spring which would increase as he put in more rudder, but he had no direct connection to the rudder itself. As you say, if the steering engine failed to move the rudder, the wheel would not "feel" any different. But I suspect that an experienced helmsman would usually know that the steering engine was down just by the feel of the ship, much as you feel your car respond to the turn of the wheel.

Cal
 
Dec 4, 2000
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Cal, once again I must respectively disagree. There is no "feedback" through an hydraulic system. The piston and gear arrangement in the telemotor would work against that. The telemotor was designed to send information, not receive it.

However, the self-centering of the system would work whether or not the QM had hands on the wheel. All that was necessary was for the system to be in the zero rudder angle position. Self-centering was necessary to keep the rudder angle/position indicator on the telemotor synchronized with the rudder.

In my opinion, steering a ship the size of Titanic would be hell in a seaway if it had rollback like a car. It might be necessary to hold several degrees of rudder for perhaps days at a time. Rollback would cause undue strain on the QM all during that time. The best situation would be for the steering system to hold the desired rudder angle until told to change.

Due to the design of the hydraulic portion of the system, I doubt the QM felt the spring action. The wheel had the same "feel" all the time, even when hard over. However, a good QM could detect through his feet what was happening to the ship. (Can't say "seat of the pants" because he was standing.)

By the way, even a good QM has trouble steering a straight wake with the best system. "Iron Mike" (automatic steering) is so much better than human muscle. Ive seen studies that show on a long voyage the slight deviations from course allowed by a human being can add 2% to 5% to the length of the trip as compared to automatic steering.

-- Dave
 
May 9, 2001
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David,

" If the port engine were run slower than the starboard, the ship would turn left. The reverse would be true if the starboard engine were slowed. About two weeks ago I talked to a German captain who brought his ship into harbor using this technique. "

Are you telling me that the recipricating engines could be run independently of one another???
I had no idea that could be done!
I've always thought of the engines as being connected or just one unit.
So, then if I understand correctly, Titanic could reduce RPM on one engine, and increase RPM on the other and thus induce a turn of sorts.
Well then could this feature account for the discrepancies in witness accounts of Murdoch's engine orders during the collision?
I mean, could he, (would he), have been ordering one engine to stop while ordering the other to just maintain full ahead?

Yuri Singleton

Sorry if this sounds so elementary a question, but this seperate engine idea is totally news to me.
 

Cal Haines

Member
Dec 2, 2000
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Tucson, AZ USA
David wrote:
> ... There is no "feedback" through an hydraulic system. The piston and gear arrangement in the telemotor would work against that. The telemotor was designed to send information, not receive it.

Not true. Unless you can show me a check valve that held pressure in one side or the other of the system, the only thing that keeps the spring in on the receiving telemotor from pushing the plunger back amidships is the pressure of the fluid on one side of the system. Not only is that pressure holding the spring back, but it is also trying to push the rack on the sending telemotor back to center. The gearing and the lever arm of the wheel give the helmsman a nice mechanical advantage to ease his work. Don't forget that many large sailing vessels were steered by ropes or chain wound around a drum connected to the wheel. The ropes/chains would drag the tiller to one side or the other. The helmsman's muscles and the mechanical advantage of the tackle had to match the many tons of force that the sea exerted on the rudder.

> However, the self-centering of the system would work whether or not the QM had hands on the wheel. All that was necessary was for the system to be in the zero rudder angle position. Self-centering was necessary to keep the rudder angle/position indicator on the telemotor synchronized with the rudder.

The self centering feature was there to synchronize the two telemotors when amidships. It really had nothing to do with the rudder angle indicators. You need separate helm angle and rudder angle indicators: If the Officer of the Deck calls for 5 degrees right rudder, the helmsman has to know when to stop turning the wheel. If he keeps turning the wheel until the rudder position indicator reads 5 degrees he will be in big trouble since the steering engine will push the rudder well beyond the desired amount. The helm angle indicator tells the helmsman what he has ordered the steering engine to do; the rudder angle indicator tells him what the steering engine has managed to get done at that moment in time. Don't forget, it takes 10 to 15 seconds for the type of steering gear on the Titanic to move the rudder hard over, but the rate at which the wheel can be turned hard over is limited only by the strength and agility of the helmsman. It's not absolutely necessary to have a helm angle indicator, the helmsman could just keep track of the number of spokes he had turned the wheel, but that could result in errors.

> In my opinion, steering a ship the size of Titanic would be hell in a seaway if it had rollback like a car. It might be necessary to hold several degrees of rudder for perhaps days at a time. ...

Hmm. I can't imagine holding a constant rudder angle for days at a time. Small corrections in the rudder angle as the ship rolls are necessary to stay on course.

> ... Rollback would cause undue strain on the QM all during that time. The best situation would be for the steering system to hold the desired rudder angle until told to change.

That may be true and that could be why modern ships function without the returning force. But in 1912 they may not have been too worried about strain on the helmsman. The helmsmen on the sailing ships, rigged as I have described, didn't have a machine to help hold the wheel. I'm sure you've seen drawings or photos of some of those ships that had two or more very large wheels on the same shaft so the several men could assist.

If they had wanted to hold the wheel over for some reason there are a couple of ways that they could do so. One is to close a valve at the sending telemotor, the other is to slip a loop of rope over one of the "handles" (probably the wrong term) on the perimeter of the wheel.

> Due to the design of the hydraulic portion of the system, I doubt the QM felt the spring action. The wheel had the same "feel" all the time, even when hard over. ...

I disagree. The force in the return spring and that felt by the helmsman would increase in direct proportion to the rotation of the wheel away from center. Unless there is a check valve in there (and none of my books mention one), the helmsman would feel the return pressure as long as he held the wheel over. I doubt that there was a check valve, because if it stuck closed they would be in real trouble! (The relief mechanism that functioned when the wheel was amidships was just a passage connecting the two sides, it had no moving parts and there was nothing to fail.) I grant you that other steering systems do not have the return-to-center feature, but the Brown system did.

If they had wanted it to function as you describe, they could have simple omitted the large return springs, yet there they are. But you don't have to take my word for it:
[hr]
Quote:

If the hand wheel is let go, the spring compression of the receiver cylinder forces the fluid through the pipes until the centre or by-pass annular space is reached by the transmitter piston, at which position the gear and rudder are "amidships".

J. W. M. Sothern, "Verbal" Notes and Sketches for Marine Engineer Officers, 17th Ed., Vol II, James Munro & Co., Glasgow, page L-18.
[hr]​
Cal
 
M

Morgan Eric Ford

Guest
The seventh edition of "Verbal Notes and Sketches" (1911) has this to say about Brown's telemotor.

"In pulling the wheel around, it will be found to become sensibly stiffer until it is hard over, so that the steersman feels the amount of helm he is giving the ship, much in the same was as in steering by hand with the antiquated winding drum and chains; and, on "letting go", the steering wheel will run back to midships together with the steering gear aft"

Morgan
 
Jul 10, 2005
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Thank you for the great information gentlemen, and to you Captian Brown for also telling me about why Greek Sailors greased their pants. I never knew they did that. What a world of knowledge you are.

This is the main thing that I truely enjoy about this board. There are many very qualified folk who have great depth of knowledge on this subject, and I don't see much about Titanic's mechanics and how she functioned. Everyone is very helpful. Thank you.

Are there any books out there that the average landlubberwoman can get her hands on that would go into more detail about Titanic's mechanics???
I find this all very interesting. And the museums, I can't wait to go and visit them. I enjoy them very much.

Hey Cal or Morgan, where can I find the Verbal Notes and Sketches???

Thank you !!!

Beverly
happy.gif
 

Cal Haines

Member
Dec 2, 2000
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Tucson, AZ USA
Hi Beverly,

I don't know of a book that will tell you, a) what machinery Titanic had, and b) how it worked. A good source for what equipment Titanic had is the Ameron House reprint of the Olympic Special Number issue of The Shipbuilder. (I got mine from the Titanic Historical Society.) How the equipment works can be found in the many marine engineering texts that are around. A lot of WWII vintage books are on the used market now. Verbal notes and Sketches ... is a good one, but it doesn't really start with the basics and walk you through everything. I would try your local library or used book store and look for Marine Engineering titles, flip through some books until you find one that is at your level.

There are some books on steam engines on-line here: http://www.history.rochester.edu/steam/

One place to buy used books on-line is from the Amazon.com used/rare books "z-shops". The easiest way to get there is
http://www.bibliofind.com

You are always welcome to ask questions here. There are also a lot of bits and pieces in the ET archives. I posted a fairly detailed description of the steering engines a while back, for example.

Cal
 

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