Comments by "Keit Hammleter" (@keithammleter3824) on "Oceanliner Designs"
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Mike claimed twice (at beginning and near the end) that growler or iceberg ice is harder than rock. That is very hard to accept. Such ice is somewhat harder than the ice you make in your fridge, because it has been compressed and contains no air bubbles. But iceberg ice is very pure H2O - you can melt it and drink it. Thus standard engineering tables are valid - the standard figure for ice well below freezing is 5 MPa. Iceberg ice has a compressive strength upwards of 5 MPa to an estimate of about 8 MPa deep inside the berg. Effectively the ship is hitting 5 MPa.ote
Stone has a compressive strength of 30 to 50 MPa depending on type (ref UKCSA).
Alternatively, you can look at the Mohs scale, which measures scratch resistance. Ice has a Mohs hardness of 2, whereas most rock is in the range 6-8. Note that the Mohs scale is sort of logarithmic, so 6 is not 3 times as hard as 2; it is about 12 times.
Or you can look at the Vickers hardness, which is an indentation test. Ice is 1.5 to 2 Vickers. Stone is not easy to measure on Vickers, but typically exceeds a few hundred. Even limestone, very soft by stone standards, exceeds 100 Vickers.
Some people think that since ice holes steel ships, it must be hard. This is not so. Icebergs hole ships because the volume of ice is such that the inertia of the iceberg means that the ice in contact has nowhere to go. Although steel has a strength upwards of 250 MPa, its only thin, so there is little inertia in it and it can move out the way.
Its the same as if you dive into water from a great height - water has a compressive strength of zero - but you can be bruised or even seriously injured, because at the speed you hit the water, the water you hit doesn't have time to get out of the way.
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I imagine it's much like emergency evacuation of a multi-story building, only worse. I was at one time a fire warden on my floor of a 20 story office building. We had a fully developed evac plan which we rehearsed. The first time we announced that there would be a drill in 2 day's time. On the day it went reasonably well, we got the whole building evacuated in 15 minutes. The fire warden team then held a meeting and we discussed lessons learnt. We then, a few weeks later, held another pre-announced drill. It went real smooth, we got everybody out in the target time of 12 minutes.
A few months later, we decided to have an unanounced drill. We got the city fire brigade to help make it realistic - they turned up with their truck sirens going. The drill was shambles. Some people panicked. Some people refused to leave their desks. Some cleared out without getting clearance from their warden. It took over 30 minutes to clear the building. And buildings don't tilt or fill with water. Our evac plan involved the phased entry of staff on each floor entering the stair wells so that the maximum number of people could be in the stair wells with gaps between groups of people so that there was no bunch-ups or congestion. It worked perfectly in the pre-announced drills, but not in the unannounced drill.
But I've worked in other buildings that made that look really good. In a 7-story building, an evac drill was so badly run that it took 40 minutes to clear the building - wardens trying to control people with load hailers with flat batteries didn't help. In that same building, when a fire alarm was triggered, big fans automatically pressurised the stairwells so that fire on any floor would not enter a stairwell. Trouble was, women found the stairwell doors unexpectedly hard to open due to the pressure and panicked.
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That men could outlive the burning of a candle is not as surprising as it might seem. In server (computer) farms, which are installed in windowless secure rooms, they don't typically use normal water sprinkler fire suppression, as water on electronic devices just makes fires worse. Instead they use gas fire suppression.
Gas fire suppression relies on the fact that the human body keeps its blood at saturation oxygen levels at all times, therefore breathing depth cannot be controlled from oxygen level. Instead, the body adjusts breathing based on the blood carbon dioxide level, which is normally very low, as is the level of CO2 in the atmosphere - its basically only a trace.
This means that you can halve the level of oxygen in the room, and provided you double the concentration of CO2, everybody breathes just fine, though their ability to perform intense exercise would be diminished. But at half oxygen level, most flames go out. I once witnessed a test gas dump in a computer room. I did not have any discomfort, though I did automatically breath a bit deeper.
A similar system is used to put out flightdeck electrical fires in aircraft.
People have trouble on high mountains where the oxygen pressure is reduced, because the CO2 level is also reduced, so the body exhales CO2 more easily, and thus compensates in the wrong direction and blood oxygen level falls.
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@PsRohrbaugh Submarines have been made with tanks open to the sea at the bottom. Submarine range is limited by how much fuel they can carry, and is never really enough. By venting some fuel tank space to sea, the fuel can be blown out by compressed air, which is nice to have if you have been depth charged and nothing works properly and you are otherwise going to sink to the bottom and die. Having valves instead of just holes is not good as they might seize. Or you can just push out some fuel, pushout some floatable junk via the torpedo tubes, and sneak off, hoping the enemy thinks he has holed you hull and you are finished.
Note that submarines have always run on regular diesel fuel, which has a specific gravity of 0.875, less than big ship bunker fuel with SG 0.95. So the chance of mixing due to rough weather is a lot less.
I don't think surface ships had fuel tanks open to sea.
You may be thinking of the World War 2 construction of British warships, particularly aircraft carriers. These were built with a "third skin" outside the armoured hull. The third skin was open to the sea via vent holes at the bottom. The idea is that enemy torpedoes would be detonated on striking the third shin, and relatively harmlessly blow the water out between the third skin and the hull. The space was never used for fuel.
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@rock-t3d2k With typical glacier ice, entrained rock, whether rock/dirt powder or large boulders, is on the bottom of the glacial thickness, which is typically 300 to 2,000 metres. This bottom layer containing entrained matter soon melts off, so by the time the bergs get near ships, there is no entrained/captured rock. Certainly not the growler ice that were the broken up remains of a glacier berg that hit the Explorer.
In any case, any entrained rock dust or small boulders would merely abrade a ship's hull and no hole it, as the ice substrate would not hold it in place against the locallised stress.
Note that ice is not a true solid. It is a plastic, this means that anything heavy trapped in it slowly migrates to the bottom. Rock is typically 8 times heavier. Thus the rate at which icebergs loose entrained rocks is faster than the rate of melting would suggest, especially the larger the rock size, since mass goes up faster with size than does surface area.
The sculpting of landscape by glaciers took place over millions of years.
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A minor error by Mike: He said the engines were diesels started with petrol. Actually, the design called for compressed air starting, as was common with marine diesels. However the compressed air system was not going to delivered in time for the scheduled flight, so they fitted a small "pony" engine to start each propulsion engine, just as a small 2-cyl engine was used to start Caterpillar tractor engines prior to the 1970's. An electric starter motor system as used in cars, adequate to start the diesels at altitude, would have been much heavier. As with the Caterpillar, the small pony engine was a gasoline unit. Had the R101 not crashed, when the compressed air starting system arrived, the gasoline pony engines would have been removed.
Mike erred in using a DC3 as yardstick. The DC3 first flew 6 years after the R101 - due to rapid progress in aircraft technology, really a different era.
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To large extent, the arguments presented do not make sense. At 5:13: "Launching lifeboats is dangerous for passengers, so let's not worry about having enough lifeboats." That's replacing risk of death with certain death. Later in the video: Using lifeboats to escape in is dangerous due to weather and sea conditions. So let's just use lifeboats to make multiple trips back and forth between the doomed ship and the rescue ship. Yeah, sure. If it's dangerous to make one trip in a small open boat, it's dangerous to make several trips.
Also stated in the video: The Titanic had safety features e.g., watertight compartments, radio, so that it should float long enough for rescue vessels to arrive. That makes some sense, but not a lot. What if it is caught in a heavy storm that delays lifeboat launching? What if it is not operating in a heavily used sea lane?
Oceanliner Designs says Harland and Wolfe were not seeking to cut costs and were keen on safety. But what is very clear here is that it is a classic case of legal requirements (lifeboat capacity related to hull size) not keeping place with advances in technology - allowing prvate industry to skimp on what they provide.
In a more ideal world, Harland & Wolfe would have said to themselves "We are legally required to provide x lifeboat capacity. But we are building a ship that is outside the passenger capacity parameters anticipated by the Board of Trade. Therefore we should honour the INTENT of the requirement, not just the literal words of the rule."
But of course, being a profit making company building for another profit making company, that's just what they did not do.
Never mind the excuses. Harland and Wolfe in combination with White Star are at fault, for not providing a means by which everyone could be rescued, even under ideal conditions.
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@DerpyPossum : Your last sentence: "They did everything they could ....." is very clearly wrong. It's wrong because the sister ship Olympic underwent a major refit as a result of the Titanic loss. The refit was driven partly by loss of public confidence in the Olympic class, and partly because of crew industrial action. Further, the third ship of the same class, had major design changes during its construction, again because of the Titanic loss.
If they could do it after the accident, they could have done it before - the only thing stopping them was competitive pressure and lack of ethics. This is self evident.
Asking "what if" in regard to safety is a standard ethical requirement of professional engineers, and has been since before Titanic. As I explained, it is not part of BoT ethics - such boards cannot anticipate technical innovation, such as the advent of 50,000 tonne liners carrying 3,300 people.
Your smartphone analogy is not a good analogy because under no circumstances can smartphones be lethal - unless you use one to batter someone to death, and that would clearly be criminal action.
A better analogy is airliners. When Boeing started to make jumbo jets, they asked "what if" in a formal process called FMEA (Failure Mode Effects Analysis) and that told them if the flight control cables failed the airplane would crash and all people would die. So their triplicated the control system with separate routing. There was no legal requirement to do so. They did it anyway, because their engineers were professionals. Unfortunately, Douglas only complied with industry norms, and several Douglas plane-loads of people died.
Lastly, as I said before, the concept of using lifeboats as ferries between ships on the open sea came from the industry, not the BoT. You are wrong there. The BoT just accepted it, until the Titanic accident showed they could not.
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Mike seemed to represent the 1958 movie A Night To Remember as pretty good. I saw this movie about 45 years ago, and at that time I thought it was good but not that good. Mike caused me to watch it again.
It's not that good. There is too much emphasis on the Titanic being supposedly unsinkable - dialog from the owner, the captain, passengers all stating that it can't sink. This unsinkable nonsense arose from newspaper articles tizzed up by second rate journalists. NOBODY in the shipping industry would have believed any ship could be made unsinkable, certainly not the builders and certainly not ship's officers.
There are too many obvious bloopers that distract your attention and ruin the intensity of the story. Possibly the movie was badly edited. dining room floors go from level to a 10 degree tilt then back to level again, then back to tilt again in consecutive scenes, then suddenly go to 20 degrees. Some events seem to be out of sequence.
A scene showing the Titanic from a distance showing the front going down at about 500 mm per second. That's way WAY too fast.
People in lifeboats some distance away from the ship were shown as hearing the band. There was no way that could happen. No amplification back then - the racket of all those people trying to yell their way into the boats would mean they couldn't hear the band either.
The movie did not show the ship breaking apart and the stern consequently, having risen up, falling back down then rising up a second time. This is understandable, as it wasn't not conclusively established that that the hull spilt until after the wreck was discovered.
Interestingly, when the berg is sighted, the movie has officer of the watch give an order "Full Astern Both" (engines - note that the centre engine was not reversible and would be automatically stopped by an order to reverse both). There has been ongoing differing views as to whether the order was to reverse engines, or was to stop them, including by Ocean Liner Designs - who as I recall thought it was an order to stop.
An order to stop both makes absolutely no sense, as the iceberg was too close to stop before hitting it - their only chance was to steer around it. Ordering Stop Both would kill rudder authority and make steering around the berg impossible. Inertia of the ship would simply keep it travelling until it hit the berg head on. We know it almost succeeded in going around the berg.
An order to reverse both would not save them, but is understandable as the officer had only a few hours on Titanic and most likely reacted automatically with an order correct for the ship he had last served on - which had no centre turbine. Titanic had only one rudder, so ordering Astern Both would not kill rudder authority but would seriously weaken it.
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I'm sorry, Mike, but you still have this in quite a mess, and added errors that were not in your engines video.
1. You have omitted the presence and important role of the feedwater heaters. They result in considerable coal saving. I have explained feedwater heating in another post to this video. Refer that post or the Shipbuilder Olympic class Special Edition June 1911 page 63.
2. You have re-stated that the steam pressure into the turbine as 9 Lb/in^2 absolute. I showed in another post to this video that a pressure that low could not be employed - it would result in too low a turbine exhaust temperature and thus cause condensation to water in the later blades of the turbine. This would result in loss of power and rapid turbine blade failure and thus would never have been allowed. Refer that post or the US DoE Steam Turbine Calculator.
3. At 5:51 you said that the "[double bottom] ... stood about 5 feet above the keel." This will mislead many if not most people, as the bottom of the double bottom is in contact with the sea - there is no projecting keel as there is in a sailboat.
4. (Minor error) At 6:23 you said feedwater needs to be topped up from the distilling plant due to evaporation and contamination from grease etc. Evaporation is basically what a boiler does - evaporation loss should not occur as nowhere in the system is water in contact with the atmosphere. The main causes of loss of feedwater are:- a) the need to blow down each boiler and clean the fire tubes periodically, b) leaks via imperfect seals; c) operator error in turning valves etc. The need to shut down each boiler in turn to clean it is why more boilers were provided than necessary for the steam consumption of the various engines and auxiliaries.
Many ships continually drained off a small amount of feed water and dumped it into the sea to prevent contaminant buildup, instead of doing boiler blow-downs as frequently, but I don't specifically know if the Olympic class did this.
5. At 9:15 thereabouts you stated that condensation in the steam pipes meant a need for steam separators. Separators were required anyway, because the steam from a continuous-flow boiler such as the Scotch boiler used in Titanic can only be wet steam, as there has to be liquid water in the boiler. To get dry steam, you would have to heat the water above the boiling point at the working pressure - that would mean no liquid water could be in the boiler to boil. Steam pipes were lagged (insulated) and condensation in the steam pipes should be minimal. This is why superheating has to be done after the boiler and not within it.
6. At 9:16 you stated that superheating heated the steam "high above the condensation temperature". That's true, in steamships generally, but it is a misleading statement. It misses the point. Superheating is not about adding lots of heat, it is about heating a liquid above the CRITICAL POINT TEMPERATURE (for H2O, 374 C or 705 F). This may or may not be well above the boiler temperature. For a boiler pressure at almost the critical point pressure (3200 Lb/in^2 for H2O) the temperature would be raised only slightly.
The critical point of a substance is the the combination of temperature and pressure that determines whther the substance can only exist as a pure gas or not. Raise it above the critical point temperature and it can only be a gas, regardless of how low the pressure is, so long as the pressure is below the critical point pressure. Superheated steam obeys the kinetic gas laws and thereby increases steam engine efficiency. Superheated steam can only be dry steam, as you have realised.
7. In the indicator diagram you showed at 13:24, you shaded the area below 14.7 Lb/in^2 absolute, and it looks like covering 1/3 the graph. You claimed that it means you get 1/3rd the power in the steam by operating below atmospheric pressure. THIS IS NOT SO. That would mean the top of the graph is at 2 atmospheres pressure. It appears from the hard to read numbers that the vertical scale is logarithmic, not linear. So the top of the graph is not 2 atmospheres, it is 10 atmospheres. In any case, Titanic's steam pressure was 14.6 atmospheres.
The turbine was able to contribute 1/3 of the total shaft output power not because there was 1/3 the energy still left in the steam, it was because turbines are about 4 times more thermodynamically efficient that reciprocating engines.
8. You claimed at 13:32 that the turbine "would actually assist the main engines by drawing steam through them. Clearly that is ridiculous. If the reciprocating engine exhaust steam went straight to the high vacuum of the condensers, a greater expansion could be designed for in the reciprocating engines and they would both be more efficient AND produce more power. The turbine is an impedance to the recip engines, not an aid. The recip engines without a turbine could produce not as much efficiency and power as the whole hybrid system, but more than they did in Titanic never the less.
9. At 13:50 you state that the condenser vacuum is created by the cooling of the steam. Clearly that is nonsense. A condenser is in essence a pipe through which the steam goes through, with cold water on the outside on the pipe to carry away the heat. In Titanic, the condensers were a very great number of pipes receiving the steam in parallel, but the principle is the same. Whatever is the pressure at one end of the pipe must be pretty much the same as at the other end. What creates the vacuum is the feedwater pumps drawing the condensed water out. Sure, a volume of steam condenses to a much small volume of water, but that isn't what creates the vacuum. If it wasn't for the pumps, the water wouldn't get sucked out and you would have no vacuum.
10. At 14:34 you stated that James Watt's engine ran purely at a vacuum. This is not so. Only the condenser was operated at a vacuum (about 0.1 atmosphere) by spray cooling. Steam pushed the working piston up. (Later Boulton and Watt used double action). Steam pressure in Watt's engines was about 7 to 10 Lbs/in^2 above atmospheric.
Possibly you were thinking of Newcomen's engine, in which steam at minimal pressure was admitted to the cylinder, than a jet of cold water condensed the steam within the cylinder, allowing atmospheric pressure on the top of the piston to push the piston down.
Newcomen engines were absolutely dreadfully inefficient, partly due to minimal steam pressure and partly because a lot of steam was wasted warming the cylinder up again at every stroke. When I was at university, the technicians had built a Newcomen engine about 1.5 metres high - it had so little power it couldn't overcome it's own friction.
11. At around 16:35 you compare Titanic's coal consumption (600 tones per day) with the roughly similar size Lucitania (1000 tonnes per day), stating that it showed Titanic's power plant was ver efficient. That is not a valid conclusion. Titanic cruised at 21 knots, Lucitania cruised at 24 knots. The power required to overcome drag rises as to the cube of speed, so with all other things equal, we should expect Lucitania to need 600 x (24/21)^3 i.e., 895 tonnes. But all other things might not be equal. It would take a lot of research to get a definitive answer.
12. At 17:23 you stated that Titanic's powerplant was "engineering genius". Hardly. Harland & Wolf tried the hybrid reciprocating/low pressure turbine configuration only once before (in 1909), and never went back to it. No other ship builder tried it. The fact is, a pure turbine installation is FAR more efficient. The reasons why the Olympic class got the hybrid system is that Harland & Wolf had a large skilled and semi-skilled workforce that made reciprocating engines in house and all relevant patents had expired. To use turbines they would have had to purchase them, so using reciprocating engines saved White Star capital expense, and delayed the point at which H&W had to start laying people with obsolete skills off.
Titanic's plant was competently designed but very much a compromise imposed by business constraints. The turbine was not used in an optimal way and could only be used when proceeding ahead at full cruising speed or close to it.
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@JedRothwell You have repeated a claim that has been made since the tests were done. But if you read the actual NIST report, the sulphur level was excessive by the standards of the day. There was a claim that over the decades, the iron could have absorbed sulphur from the sea, but this was shown to be insignificant.
However, NIST found that sulphur wasn't the main problem - it was just a contributing factor. The rivets contained really excessive amounts of slag from a bad manufacturing technique, which seriously weakened them. Hence plates parted from the hull from the shock propagating along the hull - plates that the iceberg had not hit.
Since NIST is a US agency with a world-wide reputation for scientific expertise and rigor, if NIST says the rivets were defectively made, then as far as I am concerned, the rivets were defectively made.
Slag inclusions is a problem that has been known about ever since man has been making cast iron and wrought iron. Long before Titanic. As a competent shipyard, they should have been testing samples of rivets, but evidently didn't or didn't do enough.
Harland & Wolf were a bit dodgy back then, focused on saving costs. It has been found in old records that they knowingly put cheap rivets in parts of the hull they thought should see less stress. Which was where the berg hit.
You can download the NIST report from their website.
See summary at https://www.nist.gov/nist-time-capsule/nist-beneath-waves/nist-reveals-how-tiny-rivets-doomed-titanic-vessel
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@dovetonsturdee7033 Regarding the source you asked for in your 1st para, see https://www.nytimes.com/2008/04/15/science/15titanic.html.
As to whether Titanic's rivets in the affected area, they were most certainly seriously defective, with a strength well below the norm for the time. As I said, this was determined in testing performed by an expert scientist at the US National Institute of Standards and Technology (NIST, formerly NBS). You can't get a much more authoritive source than that.
Further, photos taken around the affected area by submersible showed plates still in position but with rivets not present in the holes meant for them - confirming that the impact shock travelling down the hull caused rivets to pop off beyond the impact zone.
The NIST study plus the photo evidence showed that water entered six of the 16 water-tight compartments and this the ship could not cope with. Further, the impact area of the iceberg covered only 4 compartments as most, and the ship was designed to cope with 4 compartments flooded.
Therefore, if Harland & Wolf had performed normal rivet testing and ensured that good rivets were used, the ship would almost certainly survived.
Your comment on extra strips and replaced rivets etc is rendered unimportant by the NIST and photo evidence.
Regarding the documentary "Titanic 100 : Mystery Solved" - I had not known of its existence. I will watch it, and post what I learn from it later. It may be a week or so. I suggest you don't respond to this post until I do.
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@dovetonsturdee7033 The conclusions, that the ship was not weak, spoken right at the end of the film "Titanic 100: Mystery Solved" are not supported by established facts, and not even supported by the facts shown within the film.
The NIST showed very clearly that the ship had faulty rivets in the area of iceberg damage. The ship was indeed shoddily built and weak.
The main trust of the film is about whether the ship broke in two on the surface due to a design or construction flaw, then does not actually answer that. It shows the hull splitting down from the top with the bottom plates hanging on last, proving that the rivets there were good. But, strangely, it doesn't address why the side walls gave way. If the side wall construction, including rivets, was good, the bottom should have failed in compression.
Of course, the splitting of the hull has nothing to do with the damage caused by the iceberg, and the ship would have sunk regardless of whether the ship split in 2 or not.
The film shows rivets missing from a part of the hull that was not bent, and rivets still in place in parts of the hull horribly bent. This confirms that the rivets used, which came from several suppliers, included good batches and bad batches. some rivets were strong and some were weak.
The tests of rivets shown in this film are totally irrelevant because the rivets used were recently manufactured and did not have the slag inclusions that the rivets from the iceberg impact area had. Also the tests were done at room temperature and not at the sea temperature at which steel becomes a lot more brittle.
Further, the test was done by slow build up of force until the first rivet failed. Doing this will always make one rivet fail first, since no two rivets will have precisely the same strength and receive precisely the same load. The actual impact with the berg produced a sudden impact over a wide area, causing many rivets to fail simultaneously. Then a shock wave propagated away from the impact area, popping more rivets outside the area of actual impact.
The film completely ignores the fact that Harland and Wolf bought rivets from multiple sources - some were good and some were bad. The NIST scientists proved by testing actual rivets recovered from the impact area were bad - very bad.
"Titanic 100: Mystery Solved" must be the most repetitive and boring film I've ever seen. It told us at least 30 times a storm is coming. Told us the RUV cable was snagged at least 20 times. Told us about 10 times that the steel they used to make test rivets was 100 years old - that's of no actual significance. Told us about 20 times they are making a map of the debris field. Its heavily padded with unimportant footage. Such as showing us the survey crew pulling up and old anchor weight left by a previous survey. It showed crew pulling up a rope and the spoken commentary implied it could be a Titanic artifact - not likely given it's a modern blue nylon rope.
Not recommended.
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@dovetonsturdee7033 The expert metallurgists employed by NIST clearly established the Titanic was built with at least one bad batch of rivets and that's what caused Titanic to sink.
Go read the NIST report - an expert detail written report by expert metallurgists, illustrated by imaging, is far more authoritive than a dodgy experiment by a blacksmith who didn't even bother to replicate the correct temperature.
You can easily access the NIST summary by searching [nist titanic rivets].
Titanic was built with rivets purchased from multiple suppliers. Some rivets were good and some were not. Neither NIST nor I have claimed that ALL rivets in Titanic were faulty - just the rivets in the area of impact, where it mattered. There MAY have been bad rivets used elsewhere - that we cannot know.
Olympic was never put to the same test - it never hit an iceberg. In any case, Olympic started construction first and was launched 6 months ahead of Titanic, but the construction of the hulls overlapped. Since Harland & Wolf's normal rivet suppliers could not supply enough for both ships, H&W started buying rivets from other, smaller foundries - hence the probability of bad batches of rivets was higher during Titanic construction than it was for Olympic.
The fact that empty rivet holes were found in unbent parts of Titanic's hull during expeditions to the bottom (and this was even shown in the film) is very telling that the rivets failed due to shockwaves in the hull and not directly due to local impact with the berg. That is pretty obvious.
I said the film is bad, because it is bad. All that ridiculous repetition - we don't all have complete short term memory loss. Testing brand new rivets at room temperature, as they did in the film, is pointless.
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The presenter said that the ship's rudder was adequate and the ship quite manoeverable, but this is not true. In the situation where an iceberg or object is detected ahead, Titanic was a lot LESS manoeverable that other large ships of the day.
Notwithstanding what other ships could do because they had reversable engines, any ship that cannot turn or reverse to avoid an object in the time available after the object is sighted is NOT a safe and competent design.
Witnesses stated that the first officer included a command for full reverse, as well as his steering command. This would have been a correct command if the ship was driven entirely by reciprocating engines - it would both slow the ship down, increasing the time to turn, and maximise the amount of turning by driving water over the rudder regardless of hull velocity. The first officer probably commanded reverse because he lacked experience on turbine ships, and trials on this new class of ship were inadequate and did not include a test of avoiding an object.
At the time, most ships had reciprocating engines - turbines were new. Titanic had a turbine for cruising fuel economy, driving the 4-blade centre propellor. With the technology of the day, this turbine could not turn the propellor in reverse. Therefore, for manoevering in harbor, the ship had two smaller 3-blade wing propellors, each driven by reversable reciprocating engines (they also assisted the turbine in driving the ship forward during cruise). Thus, when the order to reverse was given, the turbine was simply just stopped, markedly reducing water flow over the rudder to only that imparted by the ship's slowing motion.
If the ship had, instead, two rudders behind the wing propellors, the ship would have been as manoeverable as other reciprocating enegine ships and the iceberg easily bypassed. If a single much larger rudder had been installed, the forward motion of the ship could have meant sufficient water over the rudder to provide enough turning to avoid the iceberg.
On that basis, the often stated view that the rudder was of inadequate size is in fact correct, and OceanlinerDesigns is wrong.
It has been speculated that if the order to reverse engines had not been given, the dramatically better rudder effect would likely have saved the ship.
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@DerpyPossum : The purpose of the trials was to verify the ship met the speed and fuel consumption requirements and establish what the manoeverability was. These days computer simulation will tell you at negligible cost, but back then the only accurate way was to go to sea and try various manoevers out.
Titanic's trails were limited to 12 hours and did not include a test for turning to avoid an object dead ahead. measured They performed an emergency stop ("normally all engines full astern - but in Titanic the turbine could not be reversed, as I said) and measured the time distance taken to achieve zero speed (3-1/4 minutes, 780 m) but did not perform an emergency turn test.
Who says Olympic's handling was any different?
The same test was not performed on Olympic until AFTER the Titanic sunk, in order that the Inquiry board could understand why it hit the iceberg.
Changing the rudder would not have been a simple thing to do. It would have cost a lot of money when money was tight. Fitting two rudders would be a major design change. Fitting a bigger rudder would require hull strengthening and a much larger steering motor. Remember that it took over 3 years to build Titanic. Olympic wasn't launched until Titanic construction was already 2/3rds complete.
Following Titanic's sinking, Olympic returned to the shipyard for major changes to make it safer, at significant cost. However, the changes were things like improving water-tight compartment integrity, so that the ship would be more likely survive a collision with an iceberg - improving turning was not considered practical.
Some people considered the captain an idiot for going at full speed in a known iceberg area. Perhaps there is some truth in that, but if adequate manoevering trials had been done, he would have known an iceberg could not be avoided by turning or stopping and would have ordered a speed reduction. It is inconceivable the captain, and first officer who was actually in charge at the time, both experienced large ship men, would not have done so. It was normal with reciprocating engine ships to go at full speed, as their much better manoeverability und usually lower speed meant they could steer around icebergs.
Some say Titanic's centre propellor was 3-bladed, some not. It doesn't really matter. It must have been appropriate in blade area and diameter to match the turbine output. In either case, ordering engine stop or ordering all engines full astern meant low water velocity over the rudder and thus a marked loss of rudder effect. A phenomena unique at the time to the Olympic class of ship and not appreciated by key people at the time.
There was some controversy over just what orders the first officer gave, as different survivors said different things. The consensus was that he ordered immediate full astern, and all stop only after the collision. But, immediate full astern or immediate all stop - it doesn't really matter - both orders would result in marked loss of rudder effectiveness, though ordering full astern was clearly the worst thing to do. Modern calculations have shown that keeping the engines at ahead would have given enough rudder effectiveness to probably just clear the iceberg.
The time to stop the Olympic class by going full astern was 3-1/4 minutes, as measured in a post-accident test. The time to put the engines full astern was considerably less than this - of the order of 30 seconds - the same time it took to fully turn the rudder.
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@MGower4465 You are right about the gas coming out cold, but there is not much if any risk of frostbite, as this system is used in rooms containing racks of computers/servers. These both put out lots of heat, typically 1000 watts/sq metre, normally removed by high capacity airconditioning, and comprising lots of metal, about 200 - 500 kg/metre, which acts as heat storage. Usually, some racks house the back up batteries, which have a specific heat about 80% of their volume in water.
Also, air normally contains about 80% nitrogen and only 20% oxygen. CO2 is only a trace. To get the oxygen pressure halved, you only need to add inert gas to add about 10% of the total room volume. So the cold is swamped out anyway. Say the gas comes out the vents at 0 C that would lower the room from a typical 25 C to 22.5 C even if the room was empty.
The reason why we stayed comfortable was not because it was a sudden dump of gas into the room. It was because human blood is normally saturated with oxygen, and the gas dump includes additional CO2 to make you breath deeper. As we were expecting it, we did notice we breathed deeper, but no discomfort. Human lung capacity is sufficient for vigorous exercise (say walking up an average hill), way greater than needed for just sitting or standing around.
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@Barkiro2010 : I'm no metallurgist or shipbuilder either, but as an engineer I do know some basic facts.
Modern mild steel that we frequently encounter has a carbon content 0 to 0.3% and negligible other impurities. This makes it by metal alloy standards fairly soft and very ductile - hit it and it deforms. In contrast, Titanic's hull plates were nominally also mild steel, but with a higher carbon content and lots of metallic impurities - being the standard of the day. This means it was a bit tougher and more springy - hit it and it will bend at bit but also transmits the shock
.Titanic's rivets were essentially (by manufacture and the method of installation) wrought iron. This gave them more strength than mild steel but also made them somewhat brittle. Experience of shipbuilders at that time showed that the brittleness was acceptable.
However, Titanic's rivets that were recovered were shown by US National Insitute of Standards and Technology to be defective. They had a high sulfur content, a lot of slag from defective manufacture and were excessively brittle. NIST found that rivets had snapped off.
I'm no metallurgist, but NIST have work class experts, and if their experts say the rivets were defective, then I certainly accept that. Their reputation is world's best. Tim Foecke was the lead scientist in the rivet analysis.
It should be noted that NIST tested rivets from the affected ship's side. It is quite possible that most of Titanic's rivets were sound, and it was bad luck that the berg hit where the rivets were a bad batch. However it is part of NIST's findings that the rivets were defectively brittle because they were incorrectly installed - insufficient control over temperature (the type of rivets required installation while red hot).
Titanic is currently disintegrating. It has lasted as long as it has due to great depth where temperature is low and oxygen also low. Plenty of old sunken ships have lasted just as long in less favourable depths.
Plenty of large businesses have gone through very tight patches, almost gone broke, but survived many more decades.
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@alfascav1754 You must have been at a dodgy university. I am an engineer. Been a competent engineer for decades. I am not a designer - I have practically no design ability.
An aspect of this that is well known by the general public is building construction. You need an architect to do the design - that is, devise how the building will look (be attractive), how it will function (don't make the kitchens a thoroughfare ) and you need engineers - electrical, hydraulic, civil, to do the engineering calculations to ensure the building is safe and won't catch fire or fall down. An architect can't do an engineer's job and vice-versa.
My university degree is in electronic engineering. That means for example, I can work out the circuit of an amplifier and calculate the specifications of all the parts so it will work efficiently and not break down a lot. But not the design - the exterior styling, making it look up to date vis-a-vis fashion, ergonomics of the user controls, etc.
When I went to university, us engineering students mainly used 3 buildings devoted to engineering. About a 100 metres away was the Art and Design building, where the industrial design students did their thing.
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@DerpyPossum : I did not dispute that H&W etc complied with LEGAL requirements. But they did not comply with MORAL requirements. They were the ones at fault by having poor ethics - they created a ship outside what the rules were written for, and thus should have gone beyond requirements.
The concept of using lifeboats as a transfer means between two ships was a commercial excuse and not a Board of Trade idea. But the Board of Trade by 1870, under pressure of ship owners, accepted not having sufficient lifeboats for all passengers and crew in regard to high passenger density steam ferries working between Britain and France. (See Parliamentary Debates, London 1870, page 323.) In open sea in any ocean in the world that an ocean liner may go is quite another thing.
It is often the case in the British system of governance that legal requirements usually don't keep up with advances in technology - in fact legal requirements get updated or created when deaths occur making the need very obvious, and such deaths often occurred, as with Titanic, when competitive pressure inhibits engineering thought.
It is not reasonable to expect that those who make the laws and rules anticipate future technical developments. They are law makers and not engineers. Thus, while the lifeboat rules were eventually shown by the Titanic to be insufficient, the Board of Trade cannot be held to be at fault. Nor can the entire shipping industry be held at fault over Titanic - that's ridiculous, as most ships were nothing like the Titanic.
The Board of Trade, when they set the rules, did not anticipate the construction of 50,000 tonne ships carrying 3,300 people across the Atlantic on a routine basis. When they set the rules, ships had much lower passenger density and nobody would have thought of such a thing.
Modern history abounds with hazards, not anticipated by those who make laws and rules, being created by technical innovations. Mostly, though, the design engineers ask themselves "what can go wrong?" and do the right thing and self-implement what needs to be done to make it safe. Nobody but the design engineers have the specialist knowledge and can do this. The Titanic engineers did not ask themselves "what can go wrong?" They were unethical and at fault.
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Did ship builders ever believe that ships had to be built of wood because wood floats, and steel does not, as Mike suggests? It seems obvious that it is the contained volume that counts, not the volume of hull material.
I've always thought that this old story arose in 19th century popular books, just as a certain book published in 1828 "A History of the Life and Voyages of Christopher Columbus" by Washington Irving, claimed that Columbus was the first to realise the world was a sphere. Sailors had known it was sphere for at least 1500 years, but like many historians, Irving thought he needed to spice up his book to win sales.
Just as another infamous history book claimed Bligh was a nasty martinet, when his record shows he clearly wasn't.
When I was in primary school in the 1950's, we were taught all sorts of nonsense, like people thought the earth was flat and Columbus had to fight that, and people wouldn't accept steel hulled ships because steel is heavier than water. The teacher hated me because I always challenged these failings of common sense, and backed it up with evidence, such as Arab trading voyages, and Eratosthenes who accurately calculated the diameter of the Earth in 240 BCE.
I was always in trouble at school. If I was a school kid today, I would probably be diagnosed with something and given nasty drugs.
And, as Mike went on to say, Archimedes understood floatation around 200 BCE - a fact that was known throughout the Middle Ages.
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Ät 3:22: "the mast is wood as you don't want metal in contact with the aerial." Well, no you don't. But you really don't want wood in contact either - even seasoned wood has a moisture contact, is made of hydrocarbon, and is very lossy to radio frequency energy. In any case, during bad storms, when you really want the radio to work, masts get coated with conductive salt spray. With the high power (10 kw) transmitters used for world-wide communication, the radio energy can burn the wood, which is very undesirable.
From the point of view of radio energy absorption, a metal mast is actually better, as it is a solid conductor and not a lossy thing.
Further, for the lightning arrestor at the top of the mast to work, there must be a wire running from it down the mast to the hull, to conduct the lightning current safely away.
Electrical insulation for the aerial wire(s) was and is provided by "egg" insulators inserted into the wire a few metres from the supporting mast. Egg insulators are made of glazed porcelain, which is an excellent electrical insulator and rapidly sheds water.
Egg insulators are around 100 mm long, too small to show properly on a whole-ship drawing and too small to show in most photographs. But if you look carefully at 2:57 just under the corner of the flag, you can see two little dots, which are the egg insulators.
Wood provides a degree of flexibility required in masts, with less weight than using steel. A steel mast would require regular inspection for corrosion, which in the top section is not so easy.
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@journeyman_philosopher I certainly did watch Mike's video. I did not say he's definitely wrong , I said that he drew conclusions on very thin ice. The only reference I could find that Titanic had a three-blade centre prop is the same one Mike quoted - that engineer's notebook. The only reference I could find that H&W were experimenting 4-blades vs 3 blades is a discussion on a Reddit forum about Titanic - hardly a reliable reference.
I think you are misunderstanding the engineering of propellor specifications as it was back then. Sure, it was rule of thumb methods rather than finite element fluid dynamics, but they weren't stupid. Considerable experience with propellor applications had been built up. I've worked for a marine engine dealer - we used much the same methods to match props to hulls and engines - and got it pretty right nearly every time if the hull people got their bit (hull drag) right.
(Props are like gears in a car - you must have the right prop blade angle etc for the ship's speed through the water, just as you need the right gear for the speed you are doing in a car.)
But sometimes the hull guys got it wrong, and they sometimes did back in Titanic's day too. When that happened, propellors got changed.
Incidentally, be aware of why professional engineers keep personal notebooks. These are the main reasons (then and now):-
1. Professional associations require the production of notebooks as proof of experience when granting corporate memberships;.
2. Source material for updating one's CV and job applications;.
3. In the event of a patent dispute or getting sued for infringement, a notebook can be presented in court as evidence of prior art;
A high level of accuracy is not required; indeed, some young chaps don't bother with a notebook until they have to produce it, and then spend a couple of evenings writing one, trying to remember what they did in their earlier years.
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@gokulgopan4397 But back then there was only 2 kinds of test they could do: a) try a configuration out in a ship, which may need several or many voyages to get enough data on various sailing conditions; or b) tank testing.
Tank testing has serious limitations, due to the need to scale the dimensions and velocities, coupled with the effects of Reynolds Number being non-linear.
All this means that for any given ship, they could get things a bit wrong, realise it from either excessive fuel consumption, excessive or too low engine RPM for a given hull velocity, or excessive vibration, or any combination of these three. If so, they could decide to try a different propellor, making an informed guesstimate as to what difference(s) the new prop should have.
If the new ship is very different to what the shipyard had built before (eg twice the displacement through increased length) there is obviously more scope to get it wrong.
But to launch two identical ships into commercial service with different propellors in order see which one works best - I don't accept that. Its just not a way to get the company manager's respect. You do your calculations (rule of thumb) and the answer is the answer - the best you can do, uncertainty notwithstanding.
If you launch the two ships with different propellors - you know that there is 100% certainty you are going to have to dry dock one of them early at huge expense and loss of revenue. If you launch 2 ships with your best idea of what the props should be, it will more than likely never be any need to early drydock one of them.
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So, the RN blamed the British public for a particularly silly mistake. Sounds worse than the RAN, who seems to have a logical policy:-
1. If possible, blame someone who died in the accident (eg blaming the captain of Voyager for a collision with Melbourne, which was due to bad signalling code design, when he wasn't even on duty)
2. If not possible to blame a dead officer, blame a civilian supplier (eg blaming a hose pipe shop for the Westralia fire, in which they used plastic hose as high pressure fuel lines - much like going to a supermarket, buying a drinking water bottle and filling it with gasoline - then blaming the supermarket for the ensuing fire).
3. If not possible to blame a civilian, blame the lowest ranking sailor possible, even though he had no option but to follow orders.
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@OceanlinerDesigns Accoding to the references I consulted, eg Nicol's book, Kylsant only wanted 18 knots. in any case it is still true that he could have had more speed with diesels, PROVIDED he told the engineers, who would then have allocated space for a third engine, or more cylinders on 2 engines.
if Shipbuilder said the engines were 10,000 IHP, then Shipbuilder was correct, But you used that figure incorrectly wrt your context. As i said, when comparing diesels with steam turbine, you need to compare apples with apples, which is shaft horsepower - which is termed brake horsepower by internal combustion men. Asturia's diesels were 7500 shaft horsepower.
As you said in your video, once a ship is designed and built, it is very hard to change engine room configuration. We may presume they found it easier to put turbines in rather than a third diesel, which would need a third shaft and prop, a new stern etc.
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A turbine input of 9 Lb/in^2 absolute cannot be correct. It is not the absolute bit that’s wrong, it’s the amount. It is likely a reporter’s error in the reference Mike cited. I show why below.
An engineer would get an accurate picture by consulting standard steam tables and a lot of math too complex to show in a YouTube post. However there are some online steam plant calculators based on accurate math that we can use.
The best and easiest to use is the US Department of Energy’s Steam System Modular Tool Steam Turbine Calculator. To use this calculator we need to enter:-
# the steam mass flow rate,
# turbine input steam pressure and temperature, and
# the outlet pressure.
# the turbine thermodynamic (isentropic ie assume no heat or mass loss) efficiency.
The DoE calculator calculates the power output and the temperature of the steam at the turbine outlet.
The DoE calculator also electrical generator efficiency as in input, because these days the main application of steam turbines is power stations. Since we only want shaft power, set this to 100%.
Harland & Wolf never disclosed the mass flow. However www.titanicology.com shows how it can be calculated from the published reciprocating input pressure, HP cylinder volume and RPM – 6200 Lb/min, i.e., 372 kLb/hr. [Note, Titanic’s boiler capacity, 260 Lb/min per boiler, exceeded this by about 17% – due to the need to clean boilers while underway and to feed electricity generators and auxiliaries. So Titanicology’s estimate is reasonable.
A reasonable value for a large low pressure turbine thermodynamic efficiency is 80%.
The outlet pressure is no problem, it is 1 Lb/in^2 absolute i.e., -13.7 PSIG , an entirely typical condenser operating point at that time. We are told by The Shipbuilder special edition that the input pressure is 9 PSIA i.e., -5.7 PSIG but it gave no temperature. This doesn't matter, we can just try progressively higher temperatures until no condensation occurs in the turbine.
Steam condensing within a turbine would cause serious problems – blade erosion, loss of efficiency, vibration due to unsteady flow conditions. It cannot be allowed.
The DoE calculator shows that 385 F just avoids condensation with 9 Lb/in^2 absolute input, producing a shaft output of 14 megawatts i.e., 18,800 HP. It can’t of course be as high as 385 F as that is close to boiler temperature. We need to change another parameter. There is little scope for changing the output pressure, increasing it to 2 Lb/in^2 absolute only drops the required input temperature to 319 F – still way too high.
Let’s try an input of +9 PSIG, with all other values unchanged. This time we get a warning that there must be water in the inlet, for all temperatures up to 238 F. We can’t accept that, as it would hydraulic lock the reciprocating engines and wreck them. So +9 PSIG cannot be right. And 238 F is still too high to allow the reciprocating engines to work at proper reduction.
Trying a turbine input of -2.8 PSIG (11.9 PSIA) in the DoE calculator, with 202 F, we don’t get condensation in the turbine or reciprocating engines. The calculator then gives us 12.0 MW i.e., 16,100 HP. Say 16,000 HP allowing for friction etc.
Conclusion: -
# A turbine input of 9 Lb/in^2 absolute is possible but not in Titanic as it requires a steam temperature almost as high as the boiler output.
# Neither can 9 Lb/in^2 gauge be right, as that would mean heavy condensation in the reciprocating engines, causing rapid catastrophic damage.
# A turbine input of 11.9 Lb/in^2 at 202 F is compatible with Titanic’s plant, does not give condensation in either the turbine or the reciprocating engines, and produces a turbine shaft output of 16,000 HP, which is correct. In practice, we would want a safety margin against condensation, operate the turbine with an input of 204 F.
Perhaps the reporter for The Shipbuilder magazine wrote down 9 when he should have wrote 11.9.
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A minor quibble unimportant to the main story: Mike's math is a bit wonky. He said the pressure at the bottom of the sea can be up to 1,000 atmospheres, That would require a depth of 10,000 metres. Depths go a bit further than that, eg the Marianus Trench is 11,000 metres.
Mike said the pressure at 1,000 atmospheres is equivalent to two SUV's per square inch. He must have an awfully big SUV. A typical larger SUV is about 4,500Lb, 1,000 atmospheres is 14,700 Lb, not 9,000 Lb.
Titanic lies at a depth of only 3,700 metres.
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I feel that our friend Mike missed a trick on this. The Enquiry looked into such things as the correctness of orders given by Murdoch once the iceberg was sighted, and the construction of the ship, but politicians are not competent to do that.
We know that Murdoch's order was to turn to left and most likely was to put all engines to reverse, to go around the berg as there was insufficient time to stop. The order to turn was correct and but the order to reverse was not, and Murdoch probably gave it because he was new to Titanic and, having no time to think, gave an order appropriate on his previous non-turbine equipped ships.
(Some people believe he ordered Stop All Engines, but that makes no sense at all - no experienced officer would give such an order.)
If the enquiry had appropriate marine experts asking the questions, instead of ignorant politicians, Murdoch's error might have come to light.
If the enquiry had appropriate marine experts asking the questions, they might have brought to light shortcomings in the construction, such as Harland & Wolf using rivets of unknown quality, but this is unlikely.
Note that while nobody in the industry would have believed that newspaper nonsense about Titanic being unsinkable, it was entirely reasonable to believe the ship could survive reasonably likely iceberg collisions. It didn't (it was known that it struck the berg in such a glancing blow that there was no hull buckling and its speed was unaffected), so it was reasonable, even back then, that a competent enquiry would seek answers as to why it didn't survive, and dig down until they found the answers.
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