Engines in reverse

[John Earl]

Something that I have been wondering about for a long time.

Following the collision, the engines were put into reverse. Didn't this have had a detrimental affect on the efficiency of the rudder?

Wouldn't a better tactic have been putting the port engine in reverse and the starboard engine full ahead or just leaving all engines full ahead?

Thanks.

 

[Michael H. Standart]

>>Wouldn't a better tactic have been putting the port engine in reverse and the starboard engine full ahead or just leaving all engines full ahead?<<

It might have been had everybody been in place to do something like that. They didn't. The ship was not at any sort of detail where everybody would be in place on the throttle controls to do any sort of complicated work with the engines.

Of course, after the accident, it no longer mattered.

 

[John Earl]

Main question

My main thought was that putting the engines into reverse reduced the efficiency of the rudder and that not altering the operation of the engines might have been of more help.

This question has intrigued me for a long time and I have seen no discussion anywhere on the subject.

 

[Arun Vajpey]

Given the circumstances, I have always believed that Murdoch made the best of a bad situation. He had a very limted time to see the iceberg, gauge the best action to take and if the ship he was going to order the ship to turn, which way to go. I am sure Murdoch had a justifiable reason - at least as he saw it - for giving his "Hard-a-starboard" order to turn the bow to port rather than the other way around or any thing else. To his credit, he almost pulled it off.

Many recent quality works on the subject query whether the "reverse engines" order was given at all and even if it was, whether it could have been put into effect within the timeframe available.

As for steaming straight ahead at the berg, I doubt anyone can be cartain that it would have been a "straightforward" head-on collision, especially when the underwater part of the berg - the part that really mattered - was not visible. A head-on collision would have caused very heavy damage to the bow and injuries and deaths among the crew and steerage passengers up front. If that had happened and the Titanic remained afloat, Murdoch would have blamed to this day for causing those deaths instead of taking evasive action, no doubt supported by many "survivor eyewitness accounts".

As has been said before, it is easy with hindsight.

 

[John Earl]

Its a matter of fact

The simple question I have pondered is; as a matter of fact, on Titanic or any other similar sized vessel, does putting engines in reverse reduce the efficiency of the rudder?

 

[Tad G. Fitch]

John, there really is no evidence other then Boxhall's statements to suggest the engines were reversed before the collision. The other two witnesses (Hichens and Olliver) to the statements Murdoch made to Captain Smith after he arrived on the Bridge and asked the First Officer what happened, recall this same conversation, but do not back up Boxhall regarding a 'Full Astern' order, and do not mention that being said.

All of the surviving witnesses who were in the engine room or boiler rooms at the time of the collision testified to a 'Stop' order being received just prior to, or just after the collision. None support the idea that the engines went astern prior to the collision. The engines certainly were reversed after the collision, but that is not what we are talking about here.

That being said, the time frame in between the warning from the lookouts and the collision was too short for the engines to have been reversed, even had that order been given. The ship was going 'Full Ahead' and nobody in the engine room was standing by expecting a 'Full Astern' order to be sent down. The process of stopping he engines while the ship had a full head of steam, and then going in reverse full speed, was complicated and couldn't be done that quickly. This is one area where First Officer Murdoch has been unfairly criticized over the years.

Kind regards,
Tad

 

[Jim Currie]

Hello John!

Very sensible questions.

My take on them is as follows:

Going full ahead starboard and half astern port is the method of turning a twin screw ship 'short round'.
There was no time for this.

Maintaining full speed on both engines would be the best option to get optimum rudder effect but again, there was the problem of proximity to the iceberg versus porpeller damage.

First consider the mechanics of ordering 'Full Astern' on a Tripple screw ship like Titanic while she was making 21.5 knots.

If Titanic's engines were suddenly ordered to turn astern (put in reverse). They would stop turning a head first. This would take about 30 seconds. The turbine prop would stop first and would be free-wheeling so it would turn relative to the speed of the ship. However the main engines would be coming to a controlled stop and would not free wheel but would cause a lot of turbulence in the vicinity of the stern post and rudder arch. When the engines started turning astern, the propellers would cause cavitation and enormous vibration. (Note that some of the crew thought the noise and vibration of ice contact was the engines going astern).
While this was happening, the rudder would become ineffective. Another thing that would cause the rudder to become ineffective would be the rapidly reducing speed caused by loss of momentum and the ship trying to push away the entire Atlantic Ocean with her starboard bow as she turned left to avoid the iceberg.

You have touched on the reasons why the nonsense about a hard left...hard right avoidance manoeuvre is just that...nonsense! To be of any use, such a manoeuvre must be made with the ships engines giving maximum assistance to the rudder.

As for the better tactic?

As Michael pointed out, thete was no time to do anything fancy with the engines. Murdoch was a very highly experieneced officer. His reaction to the situation would be professional. You and everyone else can be sure that he reacted in the shortest possible time available and in a manner that these circumstances permitted.

His first reaction was to avoid the danger ahead so he turned towards the nearest clear path. Obvioulsy this lay to the left of the ship. What else did he know?

He knew the iceberg was too close to avoid simply by turning sharp left.
He knew the iceberg was too close for the engines to bring the ship to a halt in time to avoid damage.
He knew that an iceberg might just have an underwater spur.
He Knew that turning in the way he did, the ship's stern would swing toward the iceberg.
He knew that if her stern got too close, there was a real danger of loosing at least one propeller.
He knew that the way to reduce the chance of loosing a complete prop. was to stop the engines.
He Knew How long the engines would come to a complete halt.
He knew there was not sufficient time for the engines to start turning in reverse, let alone help to brake the ship's forward motion.
He knew that in the event he did hit the iceberg he would have to stop the ship and make an inspection.

In light of all this knowledge, he chose to put the helm over hard left and ring an emergency 'Full Astern'.
This had the effect of slowing the ship down..turning her away from the danger as fast as possible while still maintaining rudder control. Meanwhile, the engines were rapidly slowing down. He possibly thought there might just be a chance for them to be at the stopped phase in the full astern manoeuvre as the stern passed the iceberg.
If there had been no contact with the ice, Murdoch would have ordered 'Stop' on the engines and then brought the ship back onto course before ordering 'Full Ahead' and resuning passage for New York.

Since there was iceberg damage, Murdoch would allow the Full Astern order to carry on until the ship was almost stopped. He would then order 'Stop'. It is quite possible that that the engines had not reached maximum revolutions astern before he did so.

Jim C.

 

[Michael H. Standart]

>>My main thought was that putting the engines into reverse reduced the efficiency of the rudder and that not altering the operation of the engines might have been of more help.<<

To answer your question directly, yes, putting the engines in reverse would have robbed the rudder of it's effectiveness.

The thing is that there is no direct evidence that this was done until after the collision with the iceberg. (Whether or not this evidence may be considered as reliable is another debate.) By this time, avoidance was a moot point and the damage was done.

 

[John Earl]

Best practice.

Michael, Jim and Tad,

Thanks for the replies.

It is likely that Mr Murdoch would have acted instinctively when he received the information that collision with an iceberg was imminent.

I wonder then what would have been considered as "best practice", if it became suddenly necessary to manoeuvre a vessel of Titanic's size either to port or starboard so as the avoid an obstacle dead ahead.

This could have been a likely topic for discussion in naval academies or other similar learned bodies of the day, concerned with the operation of vessels at sea.

In my view, given that a fundamental aspect of the collision was the manoeuvring of the Titanic after the iceberg was sighted dead ahead, it is surprising there seems to have been so little discussion on the subject either as to what actually took place or, what would have been the best course of action to take.

Finally, my questions and comments are in no way intended to infer criticism on anyone connected with the operation of Titanic on that fateful night. It is quite easy to construct questions and opinions while sitting comfortably in an arm chair, having no real concept of what could have been going through the minds of Titanic's crew on that cold dark night in the middle of the Atlantic ocean when faced with certain disaster.

Regards
John

 

[Jim Currie]

Hello John.

There is a fundemental problem with 'armchair detectives' discussing this subject.

In normal 'armchair' operations, where non-technical matters are being discussed, there is a level playing field. I.E. all the participants are usually amatures. Nothing wrong in that. However, big ship handling is a skilled occupation which is taught, not from books alone but from pracice and a fundemental understanding of the element you are working in. Not only that, it is ship-specific. No two ships handle exactly the same. AND...No two situations are exactly the same un

Chief Officer William Murdoch was at the peak of his carreer. He had no peers. He was a top dog at his trade. It is therefore rather arrogant of us all to call into question his actions that night.

You wrote:

"It is likely that Mr Murdoch would have acted instinctively when he received the information that collision with an iceberg was imminent."

Spot-on!

It is more than likely that Murdoch already knew about the iceberg when the lookouts confirmed identification by phone.
When the three bells were sounded, he would raise his night glasses and sweep the horizon slightly to each side of the bow. If there was anything there he would pick it up immediately.
Not only that, when he did see the iceberg, it's shape would tell him the direction in which lay clear water. That just had to have been to the left. That's why he went in that direction.

You also wrote:

"In my view, given that a fundamental aspect of the collision was the manoeuvring of the Titanic after the iceberg was sighted dead ahead, it is surprising there seems to have been so little discussion on the subject either as to what actually took place or, what would have been the best course of action to take."

Actually there is quite a lot on the subject on this website.

You should know that there are basically two schools of thought. These are:

1: Titanic was first ordered hard left to avoid bow contact and then ordered hard right to swing the stern away from the ice berg.

2: Titanic was turned hard left , came to a standstill, went ahead for a short period to gain rudder effectiveness and turned hard right during this period.

Number 1 is classic and perfectly sound practice if the man in charge has sufficient time to perform that maneouvre and is able to keep the engines running ahead at full speed.
From the evidence, we know that a second helm order was given but it was given after the ice berg had past astern of the ship.

I favour number 2. Simply because of the futility of number 1 and the facts that:

A. Murdoch intially thought he would miss the ice.

B. After she did hit it, she had to stop and make an inspection for damage.

C. Initially during 'B'. it was thought that Titanic had had a close shave. It would be perfectly feasible for Captain Smith to order his ship back onto her original heading to await the outcome of the damage inspection. All being well, he could continue on his voyage as intended without loosing time coming back onto her original course. If not, then he was ready to commence ship damage control and launch his boats if the need arose.

Keep asking interesting questions and giving us your considered opinion.

Jim C.

 

[Michael Kestner]

I've seen quite a bit of analysis over Murdoch's orders on this very board, John. A lot of those discussions are archived now, since the board was recently upgraded to a new software system.

One thing I would point out, that I've seen mentioned in older threads on this subject, was that Titanic's propeller setup would cause her to always turn to the left a little bit faster than to the right, all other things being equal. I don't fully understand the physics, but Titanic's port propeller rotated counter-clockwise, while the other two rotated clockwise. This was done to counter balance the thrusting of the reciprocating engines and reduce vibration, as I understand, and from what I gather it also tended to kick Titanic's stern slightly to starboard as she moved forward, meaning her head would tend to swing slightly to port. Think of it kind of like driving a car where the front end alignment is off. This was a known trait of the Olympic class ships and Murdoch would have known to use that to his advantage.

Now, whether the learned men of the day actually debated Murdoch's handling of the ship before the accident, I couldn't say. It seems to me, that most simply accepted that with the distance the iceberg was sighted at, no maneuver was possible that could have completely avoided damage. I know some of the people on this forum had the opportunity to test out a Titanic/Iceberg scenario in a simulator and, if I recall correctly, were just BARELY able to avoid collision in the simulator. It's a hard scenario to test, because we don't know the dimensions of the iceberg well enough to know exactly how far away the ship was to swing to avoid hitting the underwater portion of the berg.
*edit* Mr. Currie also made some very good points in the time it took me to write this post. Being nothing more than an "armchair detective" myself, I think it's wise to defer to his judgement in areas where his information and mine don't agree =)

 

[Doug Criner]

In my experience, reversing engines at high power causes a tremendous racket and vibration that should be heard or felt through much of the ship. I believe this is due to the props' hydrodynamic design not being ideally configured for going astern. Also, the thrust of the shaft is backwards from normal, which may play a role in the vibration? Or maybe the water being propelled forward along the hull?

But, the reason I mention this is that if the reciprocating engines had been reversed, then I would have expected there to have been many reports of a major racket - and, I believe there were none?

 

[Jim Currie]

Hello Doug!

[I]"In my experience, reversing engines at high power causes a tremendous racket and vibration that should be heard or felt through much of the ship. I believe this is due to the props' hydrodynamic design not being ideally configured for going astern. Also, the thrust of the shaft is backwards from normal, which may play a role in the vibration? Or maybe the water being propelled forward along the hull?"[/I]

And that is the experience of all mariners. It is caused mainly by 'cavitation'. This is when the propeller blade fall into a 'space' caused by turbulenc as well as areas of differing pressure. i.e. the water pressure on the lower position blade is higher that on the upper position blade. It's complicated so I won't go into the details

If you can imagine the scene underwater at the stern of Titanic as she charged ahead. Three great spirals of water being spewed in the wake. The hull form channeling water into the path of the rudder.
Suddenly, the center propeller stops. It may begin to free-wheel if the shaft is not locked but if it does it will do so slowly and drag tons of water with it,
Immediately the water pattern round the propeller area changes.

At the same time, the two outer propellers start to slow down, creating a partial drag due to the differential between their rate of turn and the forward momentum of the ship. Even more turbulence is set up. Soon, the wing propellers come to a halt.
Huge amounts of water are dragged along with the stationery blades. Then the reverse gear is engaged and the blades start turning the opposite way. At that moment, all hell is let loose in the propeller blade area. Blades start falling into spaces of unequal pressure..voids if you like. The result is huge vibration and massive 'thumps'. If the ship is at her lightest draft, she shaked and vibrates tremendously. I have actually seen light fittings and all manner of things being dispalced by it.

There is another thing that can cause vibration.

If one of the wing propellers is turning at a revolution more or less than it's mate, such an uneven situation will also cause vibration.
According to Lightoller, one of Titanic's main engines was temporarily run at 1 rpm faster during the early part of the evening of April 14. perhaps that was the cause of the 'vibration' felt by some of the passengers.
What is most certainly the case is that it was not the increased speed of Titanic that caused it.
If both wing engines of Titanic were turning at 75 rpm and their speed was increased to 76 rpm, it would not have been noticed. The average heart beat is 72. If it increases to 73, would anyone feel the difference. Is any one able to count the beats without a watch showing seconds?

Michael,

You do yourself down. You have too much sea time to consider yourself as an armchair critic.

The phenomenon of propeller transverse thrust is well known by helmsmen, even if they don't know the exact technicalities.
The turbine propeller would doubtless enhance the thrust of one of the wing propellers to the detriment of the other.

Here is a picture I found. It is possibly Olympic rather than Titanic but the principal is the same:



I remind you and other readers of the main steering forcesacting on a ship's rudder:

1..The Wake Current (The water passing the rudder due to the forward or aft motion of the ship)
2..The Transverse Thrust (the sideways push you alluded to)
3..The Screw Race with it's two components: (a) the transverse and (b) the Fore and Aft.

The turbine, center, propeller of Titanic was sited on the centerline, in the rudder arch and directly ahead of it. The wing propellers were situated 20 feet forward of the center propeller and 19 feet 6 inches out from the centerline.
With this configuration, the screw race of the wing propellers played no part in steering the ship while the ship was making more than 50 rpm. At this and higher speeds, the Wake Current and the Turbine Crew Race acting on the rudder did all the work.
When the engine revs dropped below 50, the turbine was disengaged. At these lower speeds, the Wake current acting on the rudder steered the ship.

If we apply this to the scenario I painted for Doug, you can now see how difficult it must have been to steer Titanic at slower speeds. In fact,if I remember rightly; during the Hawke incident with Olympic, the pilot used differential wing propeller speeds to make a channel turn.

I hope you can all see how it would have been impossible to employ an effective hard right turn following the intial hard left one.

However I'm open to any suggestions to the contrary.

Jim C.

 

[Doug Criner]

There is another thing that can cause vibration.

If one of the wing propellers is turning at a revolution more or less than it's mate, such an uneven situation will also cause vibration.
According to Lightoller, one of Titanic's main engines was temporarily run at 1 rpm faster during the early part of the evening of April 14. perhaps that was the cause of the 'vibration' felt by some of the passengers.the increased speed of Titanic that caused it.
If both wing engines of Titanic were turning at 75 rpm and their speed was increased to 76 rpm, it would not have been noticed. The average heart beat is 72. If it increases to 73, would anyone feel the difference. Is any one able to count the beats without a watch showing seconds?

This is comparable to a twin-engine propeller aircraft. If one engine is rotating at a slightly different rpm than the other, you'll hear the difference in frequency between the two - sort of a rawell- rawell noise. I think modern twin-engine propeller aircraft have controls to keep each engine synchronized with the other.

 

[Michael Kestner]

Jim, I think you have me mixed up with Michael Standart. I've never been to see a day in my life!