Did Titanic "bounce" off of the iceberg?

[chrismireya]

Greetings!

I was speaking with a friend recently about Titanic. He is an amateur sailor and said that he was always puzzled about something. He wondered about the science behind why the iceberg didn't cause damage along the entire starboard side of the ship. He felt that a starboard-side collision between a large steam ship (traveling the speed of Titanic) and a large iceberg should have caused both to rotate into one another as a result of the collision.

Due to the collision, Titanic, he argued, should have turned counterclockwise and the the iceberg clockwise. Since there was no damage to the middle or rear of the ship), he believes that Titanic "bounced" off of the iceberg. This would mean that it hit with a higher degree of force than the "gentle" rub mentioned by most eyewitnesses.

I admitted that I had never thought about this. The eyewitnesses -- particularly the testimonies of Lightfoot, Boxhall, Fleet, Lee, etc. seem to indicate a more gentle collision. In fact, I've always been struck by the fact that Fifth Officer Harold Lowe slept in the crew quarters through the collision and another half-hour following it.

If his assumption about how a ship and iceberg would react from a collision is true, then I stated that the shape of the iceberg might have been such that it would prevent damage to the rest of the starboard side of the ship. In other words, the iceberg would have been seemingly perpendicular to the ship itself at the time of the collision. This would allow for the type of collision described by the various eyewitnesses. The iceberg would have still shifted clockwise, but it was shaped in such a way that it wouldn't have brushed with the ship further toward the aft starboard side.

Obviously, underwater damage to the aft starboard side (in addition to the forward starboard damage) would have been catastrophic. The number of survivors would have been greatly reduced.

Are there any publications or articles about this?

 

[Robert T. Paige]

Would there have been any movement to the iceberg as a result of the collision ?
I have always envisioned an iceberg as an " immovable object " in the case of a collision with a ship due to the sheer size, etc of the iceberg compared to that of the ship ?
Of course there is the moving of the iceberg itself from the wind and currents.

 

[chrismireya]

Yes, this would mean that the iceberg shifts too. As heavy as it is, it is also floating. Titanic (which was moving forward and turning to port) would "clip" the iceberg. The iceberg would then shift clockwise.

 

[Andrew]

The iceberg would've been far too heavy to rotate under Titanic's collision.
Remember, an iceberg is enormous underwater compared to the part that's above. To all intents and purposes, they are immoveable.
Unless the collision was dramatic (which goes against all witness testimony) it wouldn't have budged an inch.
I still don't really understand how the collision managed to knock chunks of ice off the berg & fly them through the air, but that's for another thread.

 

[Jim Currie]

I do not believe that the iceberg which fatally damaged Titanic was anything more than a tall "growler". We have a description of it from AB Scarrott, so we know its shape. As for the amount underwater? Keep in mind that the berg in question was probably at least 2 years old...maybe even older. It had also been carried by wind and currents over an extensive area of ocean so it would have been getting to the unstable stage. That is the stage where the mass below the surface is getting close to the mass above it. When these are in equilibrium, the slightest movement can case the berg to overturn. I am not suggesting that the berg that did for Titanic overturned, but it is a possibility.
According to Captain Lord of the SS Californian, who transited the ice barrier 3 times and who sailed the entire north-south length of it, there were no large bergs in it or near it. I'm afraid that auto-suggestion may have played a part in people's conception of the size of the iceberg. This may be due to the popular vision of Titanic...i.e. "massive". The Rock of Gibraltar is"massive", consequently iceberg "massive".

As to whether the ship bounced or did not bounce off the iceberg?

The best way to get an idea of what happened during contact between the two, is to consider what happens to a ship when she hits a dolphin. Not, I hasten to add , the aquatic mammal , but a small mooring tower like this:

If the ship is moving in a straight line and hits the above with her starboard bow, her starboard side will want to slow down due to friction while the rest of her will want to keep moving on. The result is that the bow swings toward the point of contact (which becomes a sort of fulcrum)and the stern swings out from it. If the ship was attached at the bow to the dolphin, her stern would continue to swing out and around it.
However, the berg, like the ship , was free- floating. I imagine there would have been an element of the foregoing but as the pivot point of the ship passed the berg, she would react to her rudder and the stern would begin to swing back toward the contact point, However, this would cause contact to be lost very near to the pivot point and the stern would not have time to re-engage with the ice.

 

[Samuel Halpern]

I do not believe that the iceberg which fatally damaged Titanic was anything more than a tall "growler".

Really? According to the IIP, Growlers are floating masses of ice that are less than 14 ft in height above water and less than 46 feet in length. The berg that Titanic struck was described as about as high as the boat deck. That puts it in the range of a medium sized iceberg. As defined by the IIP a medium sized berg is from 50-150 ft in height above water and from 201-400 ft in length on the water.

According to Captain Lord of the SS Californian, who transited the ice barrier 3 times and who sailed the entire north-south length of it, there were no large bergs in it or near it.

In the morning of April 15th Capt. Rostron sent one of his officers to the top of the wheelhouse on Carpathia to count all the icebergs he could see that were 150 to 200 feet high. What he reported was a total count of 25. These 25 would in the Large size category as defined by the IIP.

 

[Jim Currie]

Really? According to the IIP, Growlers are floating masses of ice that are less than 14 ft in height above water and less than 46 feet in length. The berg that Titanic struck was described as about as high as the boat deck. That puts it in the range of a medium sized iceberg. As defined by the IIP a medium sized berg is from 50-150 ft in height above water and from 201-400 ft in length on the water.

In the morning of April 15th Capt. Rostron sent one of his officers to the top of the wheelhouse on Carpathia to count all the icebergs he could see that were 150 to 200 feet high. What he reported was a total count of 25. These 25 would in the Large size category as defined by the IIP.

You will note that I enclosed the word Growler in italics. I did that for a reason. The same reason that a small mountain would be a "pimple" compared to Everest.
I am very much aware of the IIP ice definitions. Titanic could not have been more than a mile from the offending ice when she final halted. Consequently, if it had been of any size, it would have stood out like a sore thumb/

If you read Lord's evidence, you will note that he did see icebergs of considerable size, but these were to the south east of the location...in the direction from which Carpathia had earlier come

 

[chrismireya]

Thanks, Jim. This conversation with my friend made me think about eyewitness accounts of the iceberg as well as the accounts of ice that purportedly fell onto the ship as well as why the damage was limited to the forward starboard side.

I think that the James Cameron film did a good job of recreating the collision. However, Cameron accounted for ice on the deck from the berg colliding with the top of the ship too.

Given the various descriptions of the height of the iceberg, I'm trying to think of scenarios in which the iceberg damaged the forward starboard places (that we know were damaged) and how ice could fall upon the deck. I'm also trying to reason why the damage stopped along the forward starboard side (well before amidship).

I've read the different "grounding" theories (but I am not quite convinced by them). I'm more inclined to believe that the ship glanced the iceberg -- with the force affecting both the ship and the iceberg (with enough force that caused the brittle iceberg to tip slightly and lose ice atop Titanic without actually hitting the ship above the waterline). However, I suspect that the shape of the iceberg relative to the angle of the collision was such that it avoided further impact as it turned and further damaging elsewhere of the ship.

I suspect that the list to port immediately felt during the immediate moments after collision can be explained not by grounding but by the hard turn to port, the angle of the collision and the force-related off of the iceberg.

BTW, I feel that the most probable descriptions of the iceberg come from the crew who were on watch that day. There were only a few people who saw it coming (albeit for only a short period). They got the best look at it. These include Fleet, Lee, etc.

 

[Kyle Naber]

I still don't really understand how the collision managed to knock chunks of ice off the berg & fly them through the air, but that's for another thread.

If you subscribe to the grounding theory, it’s believed that the vibrations from the ship riding over the shelf caused sort of an avalanche on the berg and ice simply rolled onto the ship.

 

[Jim Currie]

Thinking caps on again, lads/

Consider the first point if contact between ice and hull and the form of the hull between bow an the bridge and from C deck down to the damaged area along that same length of ship.

The hull form gradually reduced in width from the bridge at Watertight bulkhead "D" to the stem bar at the bow. Additionally, the hull sides in that area are not vertical but flare outward and upward to the main deck
The first point of contact was at a point where the hull is little more than 40 feet wide and the last point (forward end of boiler Room 5) at watertight bulkhead "E" where the hull is full width. Since ice was deposited on the forward main deck well, that gives us a picture of the shape of the side of the berg nearest to the ship.
There is evidence somewhere of ice being deposited on a port hole rim. If you look at the deck plans on this site, you will see dotted lines inside the outer edge of each deck below C deck. This gives you an idea of the scale of the reduction in width at each deck right down to the Tank Top.

In fact, the main deck overhung the iceberg . Because it curved inward toward the bow, part forward of the welldeck did not contact the sloping side of the berg. However as the ship passed the berg, the hull contacted the berg with the "shoulder" at the forward end of the well deck. This would dislodge any loose ice at this point. Here is a rough sketch of what I mean.

For a ship to bounce off something, that something has to be an immovable object. such a small berg would have moved... might even have tipped toward the ship at the time of contact.

Whejhn a ship "grounds" it becomes highly unstable and usually lurches to one side or the other. However such a lurch is very obvious and would be more so at a sped of 22.5 knots.

 

[Scott Mills]

You will note that I enclosed the word Growler in italics. I did that for a reason. The same reason that a small mountain would be a "pimple" compared to Everest.
I am very much aware of the IIP ice definitions. Titanic could not have been more than a mile from the offending ice when she final halted. Consequently, if it had been of any size, it would have stood out like a sore thumb/

If you read Lord's evidence, you will note that he did see icebergs of considerable size, but these were to the south east of the location...in the direction from which Carpathia had earlier come

Jim, why could she have been no more than a mile? We know from Titanic's sea trials that it took roughly 777 yards (.44 miles) to come to a crash stop from twenty knots (at the time of the collision Titanic was moving faster). I am not going to do the math, but even assuming we buy that the 'full astern' order was part of the avoidance maneuver, there is no evidence I am aware of that suggests that the engines were run full astern after the collision until Titanic came to a complete stop.

Just based on this alone, I assume it would have taken Titanic more than a mile to drift to a stop from about 20 knots. On top of this, there is a whole lot of evidence that Titanic made way again after the collision--evidence that includes a wide set of possible speeds and for a time period anywhere from 5 to 15 (or more) minutes.

Just assuming the she steamed slow ahead for only 5 minutes...

Titanic's speed at slow ahead was between 8 and 9 knots, taking the lowest value that's 9.21 miles per hour. Moving at 9.21 miles per hour for 5 minutes means Titanic would have traveled an additional .76 miles.

Now being as charitable as we can possibly be, in the sense of assuming Titanic traveled the minimum distance she could have post collision given the evidence, we would have:

1. Titanic crash stops at the moment of the collision = Titanic travels .44 miles and comes to a stop; then​

​

2. Titanic's engines begin making revolutions at slow ahead (there is some evidence it may have been faster) for 5 minutes (there is some evidence it was for longer) = Titanic travels an additional .76 miles; then​

​

3. Titanic drifts to a stop from 8 knots. I won't even include this in the calculation, but we must assume more distance is traveled; finally​

​

4. We get, at a minimum, Titanic moving an additional 1.2 miles after she strikes the iceberg (and that's not accounting for differences in drift between the two objects).​

Basically, the absolute minimum distance Titanic could have been from the iceberg when she came to a stop after the collision is roughly 1 1/4 miles.

My own reading of the available evidence though is that she steamed for at least 10 minutes after drifting to a complete stop, and she very probably was steaming at a speed closer to 11 knots. I would be very surprised indeed if Titanic foundered at a distance less than three miles from the ice she struck.

 

[Jim Currie]

Hello Scott.

You cannot use an emergency stop to compare against the movements of Titanic as she tried to avoid the berg.

When a ship makes an emergency turn, her speed drops rapidly. Add to that the impediment to forward travel due to contact with the ice. In the case of Titanic, you must also factor-in the fact that the first engine order was STOP so she would also be losing speed due to reduction in RPM. This would be further enhanced by the loss of the turbine propeller at 50 rpm and the resulting reduction in rudder efficiency. Then, for good measure, chuck in huge turbulence around the stern due to drag factor. To top it all, the ship was also turning to the southward of her track so her forward progress would also have been curtailed by that.
As for moving ahead for 10 minutes? That is simply not true. There is no evidence to show this. In fact, the evidence shows the engine movements to have been STOP...ASTERN...STOP...AHEAD...STOP. All within a time scale of 6 minutes.
A mile to the west and south is about right, I'd say.

 

[chrismireya]

For a ship to bounce off something, that something has to be an immovable object.

I think that the idea isn't that Titanic alone bounced but that both Titanic and the iceberg might have bounced off of one another. This is where nautical physics is in play. The iceberg was floating in the water. Titanic was headed directly toward it. Unless it was a massive iceberg, I suspect that the force of Titanic hitting it would have impacted the berg itself (perhaps even shifting it in the water).

I think that it is telling that the ship veered to port in order to miss it. I suspect that port gave the ship the best option to avoid collision. Given this sudden shift to port, it leads me to believe that the iceberg was probably perpendicular (in shape relative to Titanic) with the greater part of it on the starboard side. This is substantiated by the eyewitness descriptions of the iceberg.

such a small berg would have moved... might even have tipped toward the ship at the time of contact.

I agree. I am under the impression that Titanic collided with an underwater portion of the berg which tilted it and shifted it enough to throw brittle ice from its fragile nearest peak onto the ship.

I have a photo of the bow of Olympic. I will try to see if I can create a potential iceberg scenario that I think is plausible and post it here.

 

[Scott Mills]

Hello Scott.

You cannot use an emergency stop to compare against the movements of Titanic as she tried to avoid the berg.

When a ship makes an emergency turn, her speed drops rapidly. Add to that the impediment to forward travel due to contact with the ice. In the case of Titanic, you must also factor-in the fact that the first engine order was STOP so she would also be losing speed due to reduction in RPM. This would be further enhanced by the loss of the turbine propeller at 50 rpm and the resulting reduction in rudder efficiency. Then, for good measure, chuck in huge turbulence around the stern due to drag factor. To top it all, the ship was also turning to the southward of her track so her forward progress would also have been curtailed by that.
As for moving ahead for 10 minutes? That is simply not true. There is no evidence to show this. In fact, the evidence shows the engine movements to have been STOP...ASTERN...STOP...AHEAD...STOP. All within a time scale of 6 minutes.
A mile to the west and south is about right, I'd say.

Jim, there is evidence showing this. Not only from the testimony of survivors like Beesely who literally comment on the resumption of engine vibrations--and he says the time is between 15 and 20 minutes--and Gracie who testified to coming out on deck after the collision and watching passengers 'promenading' into the wind, but also from crew members... which is where the evidence gets screwy, and has led me over the years to give strong credence to the argument that Titanic intentionally made for Halifax for a short time after the collision.

For example, from the engine and turbine rooms we have the following testimony:

Greeser Fred Scott:

STOP ENGINES -Wait 15-​

SLOW AHEAD -wait 10-​

STOP ENGINES-wait 5-​

Slow ASTERN-wait 5-​

Stop ENGINES​

Trimmer Patrick Dillon:

STOP ENGINES-​

11:40- Grinding the iceberg-​

SLOW ASTERN​

SLOW AHEAD for 2 mins​

Importantly, while these men completely disagree on the timing both of them testify to Titanic's engineers being given orders to make 'slow ahead' revolutions. Just as importantly, neither of them testified to ever seeing a 'full astern' order.

If we are being honest about those 'astern' orders though, these seem much more like what I would expect if the navigation crew is bringing the ship to a halt after the collision, which for the sake of this conversation, if it means anything, it suggests that we absolutely could not rely on Titanic's crash stop time for an indication of how far Titanic may have moved after the collision.

This, of course, is not the only evidence that Titanic made way again after the collision. For example, Quartermaster Olliver noted that the telegraphs on the bridge read "Full Ahead" after Titanic was already dead-in-the-water.

Olliver also testified before the US Senate:​

​

Senator BURTON: Was she backed?​

​

Mr. OLLIVER: Not whilst I was on the bridge. But, whilst on the bridge she went ahead, after she struck. She went half speed ahead.​

​

Senator BURTON: The engines went half speed ahead, or the ship?​

​

Mr. OLLIVER: Half speed ahead, after she hit the ice.​

​

Sentator BURTON: Who gave the order?​

​

Mr. OLLIVER: The captain telegraphed half speed ahead.​

I think this all taken together is plenty of evidence that Titanic did, in fact, make way for an unknown period of time post-collision.

 

[Samuel Halpern]

I think that the idea isn't that Titanic alone bounced but that both Titanic and the iceberg might have bounced off of one another. This is where nautical physics is in play.

Do you have any idea how massive a medium sized iceberg would be when compared to Titanic? Also, to bounce off something requires some degree of elasticity. The fact that hull plates were bent enough to open several seams along the starboard side indicates that there was a high degree of in-elasticity resulting in hull deformation which absorbed the energy of impact. Whatever bouncing occurred resulted in a number contact regions along a stretch of 250 feet, or thereabouts, that opened several compartments to the sea.
If the ship bounced away, then there should have been some noticeable separation between the ship's side and the berg as it swept aft. The fact that ice came in through a number of open ports on E and D decks, that the windows on the Cafe Parisian up on B deck got wet, and that the berg passed less than about 10 ft of the afterbridge shows that the contact did not produce a billiard ball type of effect. It did impart a sway component away from the berg, which in turn would have produced an added rotational component over to port at the time of impact.
To many eyewitnesses, the contact was just a grinding sound that lasted a few seconds. To others, a slight vibration. Some people actually slept through the allision and were awakened afterward. A few were said it felt like a large wave struck the ship producing a slight swaying motion.

 

[Scott Mills]

Do you have any idea how massive a medium sized iceberg would be when compared to Titanic? Also, to bounce off something requires some degree of elasticity. The fact that hull plates were bent enough to open several seams along the starboard side indicates that there was a high degree of in-elasticity resulting in hull deformation which absorbed the energy of impact. Whatever bouncing occurred resulted in a number contact regions along a stretch of 250 feet, or thereabouts, that opened several compartments to the sea.

Sam, completely agreed. Though, to be fair, just given the laws of conservation of momentum, the ice berg likely did 'bounce.' And by bounce, I mean it probably moved a distance that could be measured in millimeters (or less).

 

[chrismireya]

Do you have any idea how massive a medium sized iceberg would be when compared to Titanic? Also, to bounce off something requires some degree of elasticity. The fact that hull plates were bent enough to open several seams along the starboard side indicates that there was a high degree of in-elasticity resulting in hull deformation which absorbed the energy of impact. Whatever bouncing occurred resulted in a number contact regions along a stretch of 250 feet, or thereabouts, that opened several compartments to the sea.

Obviously, I don't suspect that the iceberg bounced with the same force as Titanic. Rather, I do agree with my friend that the iceberg didn't simply sit still as an "immovable object." That just seems like a flawed assumption. Rather, I suspect that the action of Titanic colliding with the iceberg led to some sort of reciprocal reaction from the iceberg too. According to eyewitnesses, there was ice aboard Titanic.

I suppose that the word (for the iceberg) might be a poor choice of word. The question (in my mind) is what type of reactionary movement -- if any -- did the iceberg have when Titanic collided with it.

My friend's question caused me to consider the collision from the perspective of the iceberg. There was no known damage to the aft starboard side. It is possible that Titanic simply collided in a very peculiar way or broke off the protruding underwater appendage(s) of the iceberg before it could cause further damage along the aft starboard side.

It just seems that the collision was barely noticed by most eyewitnesses and survivors. The collision response to both the ship (52,310 waterline tons steaming at more than 20 knots) and the iceberg (of unknown size and weight). Fleet described an iceberg of about 50 to 60 feet and a collision that created no jarring to the ship (and only a "grinding" sound). Lee described the iceberg as "higher than the forecastle." Of course, this was the "tip of the iceberg."

This is no big deal. I was simply thinking about a question that a friend asked. As an engineer (but not an ocean engineer) myself, I would love to see something about the physics of the collision with icebergs. I'm primarily interested into positing why the after of the ship did not receive damage. If a ship swipes an iceberg, it seems that every millimeter would matter. This is why a bounce -- even a very small one -- of Titanic off the iceberg might have helped.

 

[Samuel Halpern]

Some time ago I calculated an estimate of what the mass of the berg would be based on a height of its peak of about 70 ft (just above boat deck level) and waterline length of about 275 ft for a medium sized berg if my memory is correct. Also note that about 85% of the berg's mass is below waterline. Anyway, it turned out that the mass of the berg came out to about 7 times that of Titanic if I recall correctly. Yes, some energy of collision will be transferred to the berg, but it will have a very small effect on the berg's movement after the collision. For calculation purposes, it can almost be considered as an immovable object.

 

[Samuel Halpern]

As an engineer like myself, you also may find this of interest:

http://www.titanicology.com/Titanica/EnergyOfCollision.pdf

 

[Georges Guay]

If Titanic would’ve bounced off the berg, the 2nd mate would certainly not be awaken by the pause of the engine purr. Furthermore, the tremendous shock wave effect would’ve given the opportunity for at least one unanimous evidence.

A subject that was not really addressed is the Wake Current flowing to fill up the cavity left by a moving ship. In fluid dynamics, a wake may either be:

• the region of recirculating flow immediately behind a moving body, caused by viscosity, which may be accompanied by flow separation and turbulence, or
• the wave pattern on the water surface downstream of an object in a flow, or produced by a moving object

A while ago, I have made that schematic drawing to explain what the current flow looked around a moving vessel and why the stern waves seemed for many, be much steeper than the bow ones. We note that theses waves are mostly formed by the flow separation; from pressure to depression. But if a wall of ice comes into the equation, that current flow will be totally disturbed. A vacuum vortex could be engendered that would easily affect the course of a moving body. That well known phenomenon is called; interaction. Every shiphandler knows that if you pass too fast and to close from a concrete wall, the vessel will be literally sucked by it. There will be a drop of water level produced by the restriction of the water to naturally flow.

So I would not be surprised that Titanic suffered from interaction against that berg. The fact that the berg kept so close to the ship side on a Hard-a-Port elm is not unknown to interaction.

As an example, to avoid interaction while meeting or overtaking a vessel barely moving, it is recommended to proceed at a maximum speed of 6 knots and at a distance no less than own breath: close and speedy enough for me! But at 22 knots, at would advice not going any closer than 1 nautical mile up wind or 2 miles downwind of an iceberg!