Titanics Rudder Size Factors

[Stephen Calcutt]

Hello everyone, I was looking at Imperator's rudder today, and I asked myself whether the reason why some might deem Titanic's rudder too small, was because it was deliberate decision by the engineers at Harland & Wolff. Since Titanic is a vessel designed for the transatlantic passenger trade I imagine there would be long periods in which the helmsman would make little change to the rudder commands. A larger rudder could also make the ship too sensitive to any input from the helmsman, making a slight turn to port into an aggressive one. The engineers at Harland & Wolff might've also considered the fact that the rudder would've been located behind the center propeller. I also asked myself whether Titanic would've made extensive use of her rudder within a busy port. Somewhere the engineers might've considered the rudder would've seen the most use, after reading an article stating how Cunard built two reciprocating ocean liners those being Franconia & Laconia after Lusitania & Mauretania due to how difficult turbiners were to maneuver within tight spaces. Perhaps since Titanic was a reciprocating vessel they would've used the quick reversing characteristics of reciprocating steam engines to maneuver in port. Maybe the unique circumstances of having a propeller in front of the rudder, the use of reciprocating steam engines, and her intended A to B run would've factored into such a decision. Another Harland & Wolff ship that has this hybrid layout would be the Justicia and she appears to have a similar rudder to length proportion as the Olympic class trio.

 

[Gordon Mooneyhan]

Perhaps since Titanic was a reciprocating vessel they would've used the quick reversing characteristics of reciprocating steam engines to maneuver in port.

I'm interested in how you conclude that reciprocating steam engines are quick reversing. Newton’s first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. To the best of my knowledge, there were no brakes on the Titanic's shafts. As a result, the propeller can't stop instantly. Interia means it will slow down as the friction in the system gradually overcomes the inertia. And no reciprocating engine can go from forward to reverse without coming to a complete stop. Yes, the bridge can telegraph the engine room to reverse, and that message will be received almost instantly. But the engine will have to come to just about a complete stop, if not a complete stop, before it can be reversed.

 

[Richard C Elliott]

Most authors nowadays do not think that Titanic's rudder was too small or, at least, notsignificantly so. See, for example, Was the Titanic's Rudder Large Enough?. In that paper Captain Weeks finds that according to two standard formulae used by naval architects the rudder was only marginally undersized. Other researchers have concluded that it was not undersized at all by the standards of 1912, though perhaps at the low end of the range.

I don't think there is any evidence to suggest that H&W were deliberately trying to keep the rudder size to a minimum. It was designed to the proportions they had used successfuly in numerous other ships - a well tried and tested design. The board of Trade inspector appeared to be quite impressed by the turning performance in Titanic's sea trials and Olympic handled quite nimbly in encounters with U-boats in wartime.

To be sure the performance was not up to the task of successfully avoiding an iceberg encountered at a distance far less than anyone at the time would have anticipated, but the rudder was not designed for that. No shipyard would have designed for that possibility.

 

[Stephen Calcutt]

Perhaps since Titanic was a reciprocating vessel they would've used the quick reversing characteristics of reciprocating steam engines to maneuver in port.

I'm interested in how you conclude that reciprocating steam engines are quick reversing. Newton’s first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. To the best of my knowledge, there were no brakes on the Titanic's shafts. As a result, the propeller can't stop instantly. Interia means it will slow down as the friction in the system gradually overcomes the inertia. And no reciprocating engine can go from forward to reverse without coming to a complete stop. Yes, the bridge can telegraph the engine room to reverse, and that message will be received almost instantly. But the engine will have to come to just about a complete stop, if not a complete stop, before it can be reversed.

Well I've read that steam engines persisted in icebreakers, tugboats, and ferries because they where quick reversing allowing them better maneuverability then say diesel boats. Here are two videos showing these engines in action.

 

[Stephen Calcutt]

Most authors nowadays do not think that Titanic's rudder was too small or, at least, notsignificantly so. See, for example, Was the Titanic's Rudder Large Enough?. In that paper Captain Weeks finds that according to two standard formulae used by naval architects the rudder was only marginally undersized. Other researchers have concluded that it was not undersized at all by the standards of 1912, though perhaps at the low end of the range.

Yes I've read that article by Captain Charles B Weeks, and I found it very informative. I see he references a text called Modern Ships written by John H La Doge and published in 1965. Sorry for asking, but wouldn't have ship design changed enough between 1900s and 1960s to make the average consensus of how large a rudder should in 1912 seem a tad undersized in 1965? I do agree the with the consensus that Titanic's rudder might've been in the mid to lower end of the range in terms of size compared to other vessels in the era.

I don't think there is any evidence to suggest that H&W were deliberately trying to keep the rudder size to a minimum. It was designed to the proportions they had used successfuly in numerous other ships - a well tried and tested design. The board of Trade inspector appeared to be quite impressed by the turning performance in Titanic's sea trials and Olympic handled quite nimbly in encounters with U-boats in wartime.

To be sure the performance was not up to the task of successfully avoiding an iceberg encountered at a distance far less than anyone at the time would have anticipated, but the rudder was not designed for that. No shipyard would have designed for that possibility.

I understand, it bothers me sometimes how some might consider the Olympic class trio to be badly designed and poorly built. When all three of these wonderful vessels passed the rigorous board of trade inspections with no issue at all. Thank you for your help it was much appreciated.

 

[Richard C Elliott]

I see he references a text called Modern Ships written by John H La Doge and published in 1965. Sorry for asking, but wouldn't have ship design changed enough between 1900s and 1960s to make the average consensus of how large a rudder should in 1912 seem a tad undersized in 1965?

Yes, I agree. Most of the formulae people use to support the argument that the rudder was undersized significantly post-date the Titanic. That is a major reason why many people think it probably wasn't undersized by early 1900s standards and, as I have said, it certainly performed to the expected standard.

 

[Stephen Calcutt]

Much appreciated for the input, I consider the Olympic class trio to be well designed ships. Technically Titanic did clear the berg or the least the portion that could be seen above water, it was the underwater portion that proved fatal.

 

[CherylThompson]

Well I've read that steam engines persisted in icebreakers, tugboats, and ferries because they where quick reversing allowing them better maneuverability then say diesel boats. Here are two videos showing these engines in action.




You've made some excellent points regarding Titanic's rudder design! Engineers likely aimed for a balance between maneuverability and stability, especially considering the ship's transatlantic role. A smaller rudder could reduce sensitivity, which is vital during long voyages. The unique propeller placement and the use of reciprocating engines would also have influenced these design choices for effective port maneuvering. I’ve been using domypaper.com for a while now, and I’ve never been disappointed. Their writers are always professional and do a great job with the assignments. I had a particularly challenging paper recently, and they handled it beautifully. The paper was detailed, well-written, and submitted before the deadline. I highly recommend them to anyone in need of writing help!

Thanks for those videos. I want to see it.

 

[Samuel Halpern]

Technically Titanic did clear the berg or the least the portion that could be seen above water, it was the underwater portion that proved fatal.

Technically? Meaning as in accordance with fact? The ship struck the iceberg. Doesn't matter what part of berg or ship came in contact which each other.

 

[Arun Vajpey]

Technically Titanic did clear the berg or the least the portion that could be seen above water, it was the underwater portion that proved fatal.

I am not sure what that is supposed to mean. From point of view of an impact and risk of flooding, running aground close to the shore etc, I would have thought that a ship's draught (draft) was what mattered most from a technical standpoint. Also, Murdoch and the others would have known very well that an iceberg would be over 8 times bulkier underwater compared with the exposed portion, which would obviously mean that the unseen part could be closer to the turning ship.