Reversing Gear vs Iceberg

[Don Tweed]

Do not know if this has been asked before so here goes. I wonder if any of the passengers or crew were awoken by the engines being thrown into reverse as compared to scraping the berg. I wonder if the "jar" some of them described was simply the engines going into reverse. Could this be possible?
Wondering aloud, Don

 

[Michael H. Standart]

When were the engines thrown into reverse?

The commonly accepted version is that this happened before the collision but there are some problems with that one, not the least of which is that testimony from the survivors who were in the engine room don't speak to that happening until after the accident.

As to who noticed it, there were passengers and crew who were already awake who noticed something happening. A shake, shuddering and the like but most of the rest who were in bed slept right through it.

 

[Malcolm Wardlaw]

Is it plausible that such large engines could be reversed in less than 40 seconds? I would be surprised if they could even be brought to rest in 40 seconds. The turbine did not run in reverse so just had to be stopped. All done against immense momentum and the windmilling power of the water acting on the propellers. It would have been necessary to apply some powerful brake to the shafts to get them to stop, then adjust them to run in reverse. If it could be done in less than 90 seconds I'll be surprised.

 

[Mark Chirnside]

Hi Malcolm,

One of Olympic's engineers offered an estimate on a similar issue. He was speaking about the engines being ordered full ahead which may influence some of the statement: 'He [the engineer] has to reverse the reversing engine from stop, he has to throw her over into ahead gear and open the stop valve -- that would't take him fifteen seconds, he could do that easily.' This engineer estimated that one of the main engines could be worked up to 77 revolutions (ahead) in one-and-a-half minutes, but clearly the ship's speed lagged the engine revolutions.

I don't have the full context for the statement, which is unfortunate, but I don't believe that the engines were operating at full speed in the circumstances which he reported. Titanic, of course was, but if these engines could be worked up to high speed in less than two minutes it would clearly have taken longer for the ship to respond and for the engines to have a significant influence on reducing the ship's headway. I'll leave judgement to a knowledgeable person, but it may be that this description was for moving the engines ahead after either being stopped or going very slowly astern...it's not in my notes but I am afraid I am not in a position to check. We really need an estimate for changing the engines from full astern to full ahead, or ideally vice versa, to my mind.

Best wishes,

Mark.

 

[Samuel Halpern]

Malcolm: Tests conducted on the Olympic showed that she could be stopped from a speed of 18 knots (60 revolutions) in 3 minutes 15 seconds. The forward travel from the time the order was given was about 3000 feet. It was also reported that the engines were not reversed as quickly as had been seen on other occasions. (Wilding, British Inquiry 25295).

 

[Samuel Halpern]

I just dug up a report by H. I. Cone that said that reciprocating engines similar to Titanic's on the battleship Delaware started to back in 10 to 22 seconds from time the order was received. This of course was with an engineering staff just waiting for this order to come down. Backing hard took from 52 to 60 seconds after order was received.

 

[Malcolm Wardlaw]

Sam & Mark, many thanks for these replies. I am amazed that such large engines could be stopped and reversed so quickly. Could they use steam pressure to stop the engines? I don't see how else they could have done it. I mean, putting a car in reverse and easing in the clutch takes about ten seconds.

 

[Noel F. Jones]

As far as I know, steam reciprocating engines are the most manoeuvreable of marine propulsion systems. The only system that theoretically could outclass the SRE would be reversible pitch propellers but I don't know of any practical application of these.

Put simply, the manoeuvrebility is facilitated by reversing the flow of steam by means of co-ordinating the drag link and stop valve, which arrests the pistons almost instantaneously and poises them for reverse movement.

Perhaps Stefan Riechel might care to 'weigh' in (weak pun on weighshafts).

Noel

 

[David G. Brown]

The time needed to reverse engines is not just a function of the machinery. It's also a function of the manning of the engine room.

The numbers of engineers varies with the time of the voyage. In ports or at other times when quick response from the engines is necessary a large number of engineers are on duty. This is called a "maneuvering watch."

At sea, the numbers of engineers are reduced to just those necessary to tend the machinery as it runs. Titanic's engineers did not expect to make any engine maneuvers for the better part of five days after leaving Queenstown. So, a "sea watch" of fewer men would have been on duty that Sunday night.

Fewer men not stationed at the engine controls meant longer human response time to unexpected orders from the bridge. This fact was recognized by the wise mariners who wrote the Rules of the Road, which include a requirement for stationing a maneuvering watch in reduced visibility when sudden reversal of engines may be needed to avoid collision.

Sailors who have experienced a true "crash back" of engines--sudden full reverse from full forward speed--never forget the experience. There are no stories among Titanic survivors of the noise and vibration such an action causes. But, there are lots of stories about some vibration in the stern. Ask David H about his mother's experiences. Also, recall the stewards in the first class galley who thought the ship had thrown a propeller blade. The ship struck on the ice in the bow, yet a lot of people placed the action at the stern. Curious.

-- David G. Brown

 

[Samuel Halpern]

You can add QM George Rowe the list of those that said he felt the vibration of the engines reversing on the poop deck after the collision.

quote:

I looked forward and was amazed to see what I thought to be a sailing vessel it was the colour as wet canvas and I said to myself, my - we've struck a windjammer but as we passed it we were so close I saw it was an iceberg and the engines started in reverse and the vibration on the poop was something terrific, I went across to the port side and pulled in the log in case it fouled the propeller, and then all was still.

 

[Aly Jones]

>>Is it plausible that such large engines could be reversed in less than 40 seconds? I would be surprised if they could even be brought to rest in 40 seconds<<

Titanic did not have 40 seconds to spare.

Going back on to topic here.

One gentleman that has traveled on the Olympic and Titanic mentioned that they were exactly the same and they run very smoothly with out a hitch(before iceberg).So throwing the reversing gear on,should have been smoothly to the passenger's that night.Other witness mentioned that it was the scrapping of the iceberg that woke them up,the reversing gear was all-ready thrown in to gear ages ago.Going by what the witness stated that night and the gentleman.Should have been a smooth change of gear.

 

[Roy Kristiansen]

>>Titanic did not have 40 seconds to spare.

Highly debatable. Read Olliver, Scarrott, and even some of the things Fleet had to say (or omitted saying) after the fact.

>>One gentleman that has traveled on the Olympic and Titanic mentioned that they were exactly the same and they run very smoothly with out a hitch(before iceberg).

Eh?? Was he speaking of having experienced a crash stop on both ships?? When and when??

>>So throwing the reversing gear on,should have been smoothly to the passenger's that night

Although Murdoch may have initially rung the telegraph for reverse, there's no confirmation that the engine room was actually able to act on it before the crash. The recollection of those people is that the telegraphs began ringing wildly - all of them - and that within just a couple of seconds (!!), the impact occurred.

A lot of people's mental conceptions of those moments on the bridge seem to have come from the various versions told by Boxhall. I'm sure I'm far from the only person to have had "difficulties" with some of the things he had to say on the subject.

 

[Haowei Shi]

In the movie,the officers pull the telemotor into full astern mode.Then the engines stoped and started to spin backwards.But the ship just crashed with the iceberg in very high speed.I think it happened on the real ship.

Haowei
FULL SPEED AHEAD

 

[Michael H. Standart]

Haowei, do yourself a favour and don't confuse the movie for reality. There are a number of controversies over exactly what sort of orders were given and what actions were actually taken, to say nothing of discrepancies in the testimony.

 

[Haowei Shi]

But the movie is kind of like the real thing!

Haowei