Question for Deckies - Going Astern.

Gareth Jones
11th June 2008, 01:50
I was watching a documentary on the Titanic the other day which alleged that on sighting the iceberg the Officer of the Watch ordered hard a starboard and full astern. (Presumably almost simultaneously or fairly close together in time).

As a former sparkie, not my neck of the woods I know, but I was once given to understand that when going astern, the rudder has little or no turning effect.

If this is the case, would it not have been better had the OOW ordered only hard a starboard and not gone astern, then perhaps the ship would have turned more to starboard and thus possibly avoided the collision ? The film suggested that given the time it would have taken to take way off the ship, going astern was a waste of time.

Hindsight is a wonderful thing, and I certainly would not want to suggest any criticism whatsoever, but would appreciate the opinions of those that really know about these things.

billyboy
11th June 2008, 02:01
Never handled anything that big myself. But. a large ship takes a heck of a time to stop. By going hard a starboard it has the effect of slowing the ship down. Add to that the engines now going full aster tends to make the ship swing to starboard faster (i believe)...(personally i would have just jumped...LOl)
I think Tmac would the best man to advise you on this query as he is well up on this subject.
But, this wonderful site being full of retired Captains i would think someone will be along soon to advise about the hard a starboard bit.

Bob McColl
11th June 2008, 06:31
I was led to believe the officer ordered the starboard engine to full astern..and the port engine full ahead with the idea of turning to starboard fast...but the starboard engine did nothing but cavitate so it did not help...I'm a leckie so I could stand corrected...

Orbitaman
11th June 2008, 07:23
As long as there is flow past the rudder, then it will have a turning effect. The idea of going hard starboard would be to start to turn the vessel to starboard as the way is taken off by going astern. Once the headway is removed, the effect of transverse thrust should take effect and start to drag the stern to port, helping the turning effect to starboard.

Once the vessel started to turn to starboard, the Officer could have 'fish tailed the rudder (working it from hard starboard to hard port, etc, etc) and this would also have reduced the headway without affecting the turn to starboard.

Better still, the Ttanic could have reduced speed in the first place, being in a known iceberg field, then perhaps the incident wouldn't have occured at all!

Chouan
11th June 2008, 10:30
If the OOW had done nothing it would have been better, as the effect would have been do drive the bows into the iceberg, thus crushing the bows, probably up to the collision bulkhead, but the watertight integrity of the rest of the hull wouldn't have been compromised.
However, as Orbitaman suggests, going slower in the first place might have been a better idea. Telling the boss to stuff his job as well, probably.

waimea
11th June 2008, 11:04
If I recall the berg was on the starboard side and the ship had to turn to port to avoid it. The order hard a starboard was correct as in those days British ships still used the old helm orders when putting the helm to starboard caused the vessel to turn to port. The change came after Titanic and now one turns the wheel in the direction of the turn.

ROBERT HENDERSON
11th June 2008, 14:09
No doubt the officer on watch on the Titanic should have taken perhaps a different course of action, hindsight is a truly wondrous thing. If not all, I am sure most of us who have been in charge of a ships bridge have made split second decisions with not always the results we would wish for, when after the event we have had time to analyse we know we should probably taken different action. I remember when I first took command I was told by a very experienced master, the best shiphandlers are on the quayside or by the guardrails. Unless you were actually there to see what happened I do not believe anyone is in a position to criticise the OOW on the Titanic.

Chris Isaac
11th June 2008, 14:55
Anyone who has sailed as a watchkeeping officer or master on any deep sea vessel particularly a passenger liner and is in possession of a foreign going master's certificate is fully entitled to criticise the OOW.

He was going too fast in an area known to contain ice and was keeping an inadequate lookout...... end of story!

If he had been proceeding at a safe speed and had kept and adequate lookout then such a "split second" decision would not have been required.

What the Fug
11th June 2008, 16:50
If he had been proceeding at a safe speed and had kept and adequate lookout then such a "split second" decision would not have been required.


And he may have ended up at the back of the Q for promotion.

nothing is black & white till after the fact

The above goes for any industry

Ian F
11th June 2008, 19:12
I add yet another of the endless arguments to the "what ifs","if onlys" "he should haves", "he shouldnt haves" Titanic was triple screw.The main screw
was turbine driven and consequently of very poor stern power.The port and starboard screws were steam reciprocating, and smaller.The rudder was of the standard unbalanced design of that period.To try and manoeuvre that in an emergency would have needed more than the current practice at that time.The Captain,Officers and Chief Pilot Southampton did not appreciate the difference in the handling of such a large vessel. It was not their fault either.Unlike the Royal Navy,the Merchant Navy officers did not have the advantage of running in a new design,in order to see how she handled,among other things. ( I am a former Pilot, and I hated Turbines..no stern power)(Cloud)

Tony D
11th June 2008, 20:12
I watched a documentary on the Titanic sinking were i was stated one reason for the possible confusion the order given was "Port You Helm" which meant go to starboard,and a this was the period when orders to the helmsman were changing to the more modern style ie "hard to port" and the helmsman mistakenly turned to port rather than starboard.
:confused:

surfaceblow
11th June 2008, 20:45
There are handling differences due to the different propulsion equipment. But being an ex Chief Engineer of both Steam Turbines, Turbo Electric, Medium Speed and Slow Speed Diesels. For maneuvering I prefer plants with Controllable Propellers or electric, then steam turbines, last is the direct reversing diesels. With a CP you have almost 100 per cent power in both directions and no changing direction of the prime mover. A steam turbine astern rating is usually 70 per cent. At least you need not be under five knots to go astern. I always remember the builders sign for a B & W engine by the main engine throttle on the Bridge and Engine room Console stating the serious damage will be done to the Main Engine if engine is reverse above 5 knots. The few times that the engine was put in reverse above 5 knots all of the start air was use to brake the engine and there was very little air left to restart the engine in reverse.

You also can remove way on the vessel using the astern turbine if you do not mind the noise of the wrong direction alarm especially when getting a dead slow bell from full ahead. Of course being in the engine room I can hear the propeller caviate from going to fast in shallow water.

Joe

Jim S
12th June 2008, 18:19
I add yet another of the endless arguments to the "what ifs","if onlys" "he should haves", "he shouldnt haves" Titanic was triple screw.The main screw
was turbine driven and consequently of very poor stern power.The port and starboard screws were steam reciprocating, and smaller.The rudder was of the standard unbalanced design of that period.To try and manoeuvre that in an emergency would have needed more than the current practice at that time.The Captain,Officers and Chief Pilot Southampton did not appreciate the difference in the handling of such a large vessel. It was not their fault either.Unlike the Royal Navy,the Merchant Navy officers did not have the advantage of running in a new design,in order to see how she handled,among other things. ( I am a former Pilot, and I hated Turbines..no stern power)(Cloud)

If I may make a correction to the above - Titanic's propulsion machinery consisted of 4 cylinder triple expansion steam reciprocating driving the port and starboard propellers- a low pressure steam turbine taking the exhaust from the two reciprocating engines drove the centre propeller. While the two reciprocating engines were reversible the low pressure steam turbine on the centre propeller was not and only ran ahead.
For manoeuvring only the two reciprocating engines would be used exhausting into condensers. At "Full Away" on passage this exhaust would then be diverted to the low pressure turbine to provide additional power.
I believe the total power developed by Titanic (and her Olympic Class sisters)
was in the region of 50,000 hp of which the reciprocating engines developed some 15,000 hp each (at least).
I assume that when the bridge requested Titanic's engines be put astern some minutes would have elapsed as it would have taken the engineers some time to divert the exhaust from the reciprocating engines from the low pressure turbine to the condensers. As an aside in the Titanic film an underwater shot as the ship moves off the quay at Southampton shows all three propellers starting to rotate - this is wrong for the reasons given above.

You are correct though in your opinion regarding the astern capabilities of a number of turbine ships. A sustained "Full Astern" or worse still a "Double Ring Full Astern" could deplete the steam pressure and sometimes the condenser vacuum of many ships leading to acute nervous exhaustion among the engineering staff.

randcmackenzie
13th June 2008, 00:48
"4 cylinder triple expansion "??

Quadruple expansion pehaps?

JimC
13th June 2008, 12:25
I watched a documentary on the Titanic sinking were i was stated one reason for the possible confusion the order given was "Port You Helm" which meant go to starboard,and a this was the period when orders to the helmsman were changing to the more modern style ie "hard to port" and the helmsman mistakenly turned to port rather than starboard.
:confused:

Usual cod's wallop documentary stuff! In actual fact, the helmsman at the time was in an enclosed steering space with a junior officer standing behind him to ensure that the correct order was followed. This was standard practice then. The bridge had a junior and senior officer on every watch.
At the time in question, according to the evidence given by the quartermaster he hard-a-starboarded the wheel (turned it to port) and it remained in that position after the collision.

Jim S
13th June 2008, 13:09
"4 cylinder triple expansion "??

Quadruple expansion pehaps?

Hi,

It was quite common on larger powered steam reciprocating engines of that era to have triple expansion engines with four cylinders. Normally this was to reduce the diameter of the low pressure cylinder so the configuration might be one HP, one IP and two LP cylinders. Otherwise LP cylinders in excess of
7 feet diameter were not unusual.
Exhausting the reciprocating engines to a Low Pressure turbine increased the overall thermal efficiency of the installation.

There were of course quadruple expansion engines - The most notable probably being the German liner Kronprinzessin Cecilie of 1907 which had four quadruple expansion engines, two on each shaft developing a total of 40,000 ihp. Each engine had three cranks and the configuration was a HP mounted above the first IP on the centre crank the second (larger bore) IP on the forward crank and the LP on the after crank. This LP cylinder was some 2,850 mm bore (93.5 inches). - A rather large and complicated arrangement that the steam turbine soon eclipsed. Consider that the largest bore diesel engines in service are around 1000 mm.

Jim S

JimC
16th June 2008, 12:33
And he may have ended up at the back of the Q for promotion.

nothing is black & white till after the fact

The above goes for any industry

I have just read Dr. Paul Lee's latest E book on the subject. It is extremely thorough and produces a great deal of actual fact - little or no fiction. For those who like a bit of mental exercise I thouroughly recommend it. I believe It enables the reader to form a personal opinion based on fact without all the previous garbage that has been written about the subject.

Jim C.

JimC
16th June 2008, 12:37
I add yet another of the endless arguments to the "what ifs","if onlys" "he should haves", "he shouldnt haves" Titanic was triple screw.The main screw
was turbine driven and consequently of very poor stern power.The port and starboard screws were steam reciprocating, and smaller.The rudder was of the standard unbalanced design of that period.To try and manoeuvre that in an emergency would have needed more than the current practice at that time.The Captain,Officers and Chief Pilot Southampton did not appreciate the difference in the handling of such a large vessel. It was not their fault either.Unlike the Royal Navy,the Merchant Navy officers did not have the advantage of running in a new design,in order to see how she handled,among other things. ( I am a former Pilot, and I hated Turbines..no stern power)(Cloud)
Actually the turbine was not in operation at that time. Its a complecated story but I belive, well documented.

JimC
16th June 2008, 12:46
I was led to believe the officer ordered the starboard engine to full astern..and the port engine full ahead with the idea of turning to starboard fast...but the starboard engine did nothing but cavitate so it did not help...I'm a leckie so I could stand corrected...


Actually port and starboard reciprocating engines were put at full astern. The centre turbine was not in operation. Cavitation could possibly have occurred initially in the scenario you heard of as the vessel was doing about 22 knots at the time. Probably did, momentarily anyway, as the momentum caused a drag flow when all three props were stopped. Any ideas on this?

kewl dude
17th June 2008, 06:01
http://www.encyclopedia-titanica.org/titanic_prime_mover.html

"As most us know, the triple-screw steamer Titanic, and her sister ship Olympic, were propelled by a combined machinery arrangement consisting of two reciprocating engines and a single Parsons’ turbine. The reciprocating engines were of the triple-expansion type with one high-pressure cylinder, one intermediate-pressure cylinder, and two low-pressure cylinders. The Parsons’ turbine, which was fed by exhaust steam from the reciprocating engines, was a low-pressure reaction type. Each reciprocating engine drove one 3-bladed wing propeller of 23˝ feet diameter, one on the port side of the vessel, and the other on the starboard side of the vessel. The turbine engine drove a four-bladed propeller of 17 feet diameter located on the ship’s centerline directly ahead of the rudder. The reciprocating engines were designed for 15,000 indicated horsepower (IHP) each when running at 75 revolutions per minute. The turbine was designed to develop about 16,000 shaft horsepower (SHP) when running at 165 revolutions per minute. At those numbers of revolutions, the ship was expected to make 21 knots.1 Titanic’s propelling machinery was registered at 50,000 horsepower. Standard “normal full revolutions” in service was considered to be 78 revolutions per minute for a speed a little over 22˝ knots. When running ahead at 83 revolutions per minute on her reciprocating engines, the entire power plant would develop about 59,000 horsepower, of which 18,000 horsepower would be contributed by the turbine.2 When carrying those number of revolutions, the ship would have made close to 24 knots through the water."

Greg Hayden

Mark Chirnside
18th June 2008, 15:11
Greg,

The article you cited from the Encyclopedia Titanica website was written by my colleague Sam Halpern. It is a very useful reference tool and I was pleased to be able to help him with it.

Best wishes,

Mark.

Geoff of Hull
18th June 2008, 15:30
Very interesting stuff about the Titanic one I came across lately that it was down to the second mate who had been working bye before she sailed taking home the key to the binocular locker!!!so the lookouts never had binoculars which might have saved the day..But I find that hard to believe as I first went to sea in 1963 and during lookout duties be it focastle head or monkey island or wing of the bridge I was never given bins ..I am still serving now and I am off Singapore and even to this day I would not touch bins on watch as they could be tuned into the officer of the watches sight.Interesting to find out if anyone has been supplied with binoculars on watch in a normal procedures position..Geoff

eddyw
18th June 2008, 21:49
The lookouts had an impossible task. Icebergs could be spotted because of waves breaking at their base but there was no moon and no wind. Also the air temperature was near freezing and going through it at 22knots must have been eye-watering. The binos would have made little difference. I think they did well to spot it when they did, by which time it was too late to avoid (estimated two lengths). Ironically had they not spotted it so soon Mr Murdoch would not have had an opportunity to try to steer around it, Titanic would have hit it head on and despite a badly crushed bow would have survived!
There was no confusion over the helm order "Hard a Starboard" the wheel being straight away spun to port. The problem was the immediately following orders "Stop. Full Astern". These delayed the swing to port by reducing the flow past the rudder and produced the fatal glancing blow.
A lot of this was established by the experiments conducted by H&W with the Olympic after the disaster.

JimC
19th June 2008, 16:06
The lookouts had an impossible task. Icebergs could be spotted because of waves breaking at their base but there was no moon and no wind. Also the air temperature was near freezing and going through it at 22knots must have been eye-watering. The binos would have made little difference. I think they did well to spot it when they did, by which time it was too late to avoid (estimated two lengths). Ironically had they not spotted it so soon Mr Murdoch would not have had an opportunity to try to steer around it, Titanic would have hit it head on and despite a badly crushed bow would have survived!
There was no confusion over the helm order "Hard a Starboard" the wheel being straight away spun to port. The problem was the immediately following orders "Stop. Full Astern". These delayed the swing to port by reducing the flow past the rudder and produced the fatal glancing blow.
A lot of this was established by the experiments conducted by H&W with the Olympic after the disaster.

Doubtless the 'bofins' are meticulously correct in their experiments but lots of us herein know full well that in reality; when turning a vessel sharply- particularly a large one- the momentum effect causes the ship to continue to travel in its original direction for some time until re-adjustment takes place.
This was one of the reported problems encountered in the early days by VLCCs making the Malacca Straits passage when rounding Raffles Light. I suspect that a sudden change of direction in a big vessel moving at 22 knots would have exactly the same effect. 'Titanic' would have to have had enough sea room to complete the turn with all it's associated effects before hitting the berg. She did not have that luxury. Articles and books by Mark Chirnside, Dr. Paul Lee and Sam Halpern to name the most prominent desciples; should be read. It's nearly all there for those who are really interested in a fascinating subject

JimC
19th June 2008, 16:12
Very interesting stuff about the Titanic one I came across lately that it was down to the second mate who had been working bye before she sailed taking home the key to the binocular locker!!!so the lookouts never had binoculars which might have saved the day..But I find that hard to believe as I first went to sea in 1963 and during lookout duties be it focastle head or monkey island or wing of the bridge I was never given bins ..I am still serving now and I am off Singapore and even to this day I would not touch bins on watch as they could be tuned into the officer of the watches sight.Interesting to find out if anyone has been supplied with binoculars on watch in a normal procedures position..Geoff

Don't think you'd get any argument there. From experience, the usual way to 'look-out' is to cast your eyes round the horizon - not looking at it directly but focussed just above it. In this way, the eyes are drawn to anything unusual in the field of vision such as an object or light. Binoculars, however are very good once an object has been located if that object requires closer attention - such as someone or some ship sending out a distress.

JimC
19th June 2008, 16:42
http://www.encyclopedia-titanica.org/titanic_prime_mover.html

"As most us know, the triple-screw steamer Titanic, and her sister ship Olympic, were propelled by a combined machinery arrangement consisting of two reciprocating engines and a single Parsons’ turbine. The reciprocating engines were of the triple-expansion type with one high-pressure cylinder, one intermediate-pressure cylinder, and two low-pressure cylinders. The Parsons’ turbine, which was fed by exhaust steam from the reciprocating engines, was a low-pressure reaction type. Each reciprocating engine drove one 3-bladed wing propeller of 23˝ feet diameter, one on the port side of the vessel, and the other on the starboard side of the vessel. The turbine engine drove a four-bladed propeller of 17 feet diameter located on the ship’s centerline directly ahead of the rudder. The reciprocating engines were designed for 15,000 indicated horsepower (IHP) each when running at 75 revolutions per minute. The turbine was designed to develop about 16,000 shaft horsepower (SHP) when running at 165 revolutions per minute. At those numbers of revolutions, the ship was expected to make 21 knots.1 Titanic’s propelling machinery was registered at 50,000 horsepower. Standard “normal full revolutions” in service was considered to be 78 revolutions per minute for a speed a little over 22˝ knots. When running ahead at 83 revolutions per minute on her reciprocating engines, the entire power plant would develop about 59,000 horsepower, of which 18,000 horsepower would be contributed by the turbine.2 When carrying those number of revolutions, the ship would have made close to 24 knots through the water."

Greg Hayden
Obviously these speeds ignore slip.. i.e. difference between engine speed and actual speed found by actual distance travelled divided by time travelled expressed in knots. What was the total BHP available to turn the props?

eddyw
19th June 2008, 16:56
Doubtless the 'bofins' are meticulously correct in their experiments but lots of us herein know full well that in reality; when turning a vessel sharply- particularly a large one- the momentum effect causes the ship to continue to travel in its original direction for some time until re-adjustment takes place.


The experiments by 'the bofins' were not carried out on a VLCC but on Titanic's identical sister Olympic. At 22 knots it took 37secs after the rudder was hard over before the direction altered two points. The order to stop the engines would have tended to reduce the rudder action and therefore delayed the swing. Rudder pressure depends on the square of the speed of the water past the plate and this speed would at once have been restricted by stopping the screws.

JimC
19th June 2008, 19:54
The experiments by 'the bofins' were not carried out on a VLCC but on Titanic's identical sister Olympic. At 22 knots it took 37secs after the rudder was hard over before the direction altered two points. The order to stop the engines would have tended to reduce the rudder action and therefore delayed the swing. Rudder pressure depends on the square of the speed of the water past the plate and this speed would at once have been restricted by stopping the screws.

I've no problem with that and understand the principal well but even if she did answer the helm as you point out - she would still have travelled - in this case - a significant distance(almost sideways) in her orginal path. This can be seen even in small harbour craft. I think we are discussing two different motions here - turning and slewing. The stern of a vessel turning at speed will also slew under these circumstances. A ship ain't on rails!
Land based vehicles do it as well but require great speed to do it. Obviously water does not afford much resistance to it.

eddyw
20th June 2008, 00:42
I've no problem with that and understand the principal well but even if she did answer the helm as you point out - she would still have travelled - in this case - a significant distance(almost sideways) in her orginal path. This can be seen even in small harbour craft. I think we are discussing two different motions here - turning and slewing. The stern of a vessel turning at speed will also slew under these circumstances. A ship ain't on rails!
Land based vehicles do it as well but require great speed to do it. Obviously water does not afford much resistance to it.

I agree. I don't think we're at odds here. Even if Mr Murdoch had not ordered "Stop" it seems likely Titanic would still have struck the ice, perhaps further back along the hull with even worse damage since the larger compartments would have been breached.As well as the yaw to port initiated by the rudder there would also have been a lateral movement to starboard bringing her closer to the iceberg.I think the attempt to avoid it was probably doomed from the start but the poor man cannot be blamed for trying.
The fundamental mistakes I think were were the choice of course and speed and for those responsibility rests with Capt Smith.