Why Did Her Stern Vibrate So Much?

this video contains an ad for brilliant get started for free at brilliant.org casual navigation when you see an early 20th century liner it just looks like such a comfortable and glamorous way to cross an ocean but the truth is sometimes somewhat different take the rms lusitania for example she was plagued throughout her life by vibrations so severe that they would render half the ship uninhabitable in fact if you've taken a cruise recently you may well have felt the same thing on your ship and wondered what was going on to find out let's take a look at the lusitania and explore the vibrations as we tell the story of her life during the late 19th and early 20th centuries the only way to cross the atlantic ocean between europe and america was by ship it was a time of mass immigration meaning there were growing numbers of people looking to make the crossing naturally lots of companies sprung up to cater to the market each competing for their share of passengers ship design developed rapidly with companies frequently producing the new biggest fastest or most luxurious ships continuously innovating to stay at the top of the game of course for you to stay at the top of your game you don't need to design ships as you can instead check out this video sponsor brilliant with brilliant you learn interactively with fun hands-on lessons in math science and computer science boost your creative problem-solving skills by solving fun problems with step-by-step solutions rather than just memorizing an answer a great place for you to start would be this course on scientific thinking in it you'll find a module on buoyancy where you're presented with a series of real-life problems to solve interactively later on there are even demonstrations of relativity using boats on a river surprisingly topical when it comes to maritime navigation of course that's not all as you can choose from over 60 other courses designed for all ability and knowledge levels you'll be sure to find something that interests you with topics ranging from logic and problem solving right the way through to astrophysics and quantum mechanics so join the millions of people already learning on brilliant with a special offer just for this channel's viewers head to brilliant.org casual navigation to get started for free with brilliant interactive lessons and the first 200 viewers will also get 20 off an annual membership anyway witcher said that shipping companies were forced to continuously innovate to stay competitive well that was until a wealthy chap jp morgan had a different idea he wanted to instead monopolize the industry effectively owning all the lines so that he would make money regardless of which ship you sailed on he created the international navigation company cooperating with the magnates from the american line the red star line the atlantic transport line the white star line the leyland line the dominion line and he had profit-sharing relationships with the hamburg america line and the north german lloyd line he acquired a 51 stake in the dutch holland america line and made offers to purchase the cunard line the thing is by then the cunard line was pretty much the only british company left operating and its purchase would mean the loss of the entire british liner fleet with far-reaching consequences not only would it be an embarrassing loss of national pride but it would also mean a loss of merchant vessels that the british government could call upon during times of war so in 1903 the government agreed to help cunard remain competitive by providing a loan to finance two new ships as well as giving them an annual operating subsidy and a healthy royal mail contract you can always tell the ships that have one of these contracts as they receive the prefix rms or royal mail ship there have been hundreds of them including the titanic carpathia lusitania mauritania and even modern ships like the rms queen mary 2. although she received it from the royal mail as a gesture to cunard's history rather than because she actively carries mail anyway in return for british government financing cunard agreed that the two new ships would be built to british admiralty specifications and made available to the government during times of war three years after the agreement in 1906 the first ship was launched from the john brown shipyard on the clyde and was christened rms lusitania her name comes from a roman province located on the iberian peninsula in modern day portugal at the time of her launch lusitania was the world's largest passenger ship although she lost the crown only three months later with the launch of her sister the mauritania anyway a year after she was launched lusitania began sea trials impressing the admiralty by achieving speeds of over 25 knots but there was a problem at high speeds the ship would vibrate in exactly the same way that a ruler vibrates when you ping it off a table the bow and stern shook so much that they became uninhabitable now that was a problem because at the stern there were important areas such as the second class dining room which obviously had to be used they needed to find out what was going on and they had to have a solution it turns out the vibrations were caused by interference between the wakes of the propellers lusitania had four one more than most ships which was needed to transmit the engine's power to propel the ship to record-breaking speeds for efficiency the imbal propellers rotated inwards and the outboard propellers rotated outward this meant that the water between the propellers all flowed in the same direction cutting down on inefficient eddy currents and things but it also meant that as the blades rotate they all throw water against the hull at the same time one hit per blade per rotation not only that but if you look carefully at the propeller blades you'll notice that they're not in the same type of water the whole time during this part of the rotation they're in the disturbed water near the hull and during this part they're in the clean water away from the ship as the blade travels through the different types of water the shocks that it feels are passed up and into the ship's superstructure when the propellers rotate at a certain speed those shocks can match the resonant frequency of the hull inducing violent vibrations across the entire ship interestingly this problem is not confined to the past the passenger ship i used to work on suffered from this exact same effect she was originally built with twin outward turning propellers best for maneuverability and things but the vibrations were so bad that they had to swap the propellers to be inward turning instead most pilots would question it when they came aboard because it's so rare for twin propellers to be inward turning needless to say it didn't completely solve it so we still had specific propeller revolutions that were banned because those were the ones that match the hull's resonance anyway i digress on lusitania they determined that the best solution was to add internal stiffening at the stern of the ship so they had to completely rebuild the second class areas incorporating the new strengthening into the decorative scheme still it never truly solved the resonance as lusitania and her sister the mauritania were plagued by vibrations throughout their lives anyway in september 1907 lusitania departed liverpool on her maiden voyage she called at queenstown to pick up more passengers before setting off across the atlantic taking only 5 days and 54 minutes it was still 30 minutes shy of the record set by kaiser vilham ii but her engines were still not run in and she had been delayed by fog on a second crossing however she had better luck and managed to do it in four days 19 hours and 53 minutes claiming the blue ribbond she was soon beaten by her sister of course who went on to hold the record for the following two decades between 1907 and 1915 lusitania made 201 successful crossings between liverpool and new york but of course by then war had broken out in europe demand from passengers had dropped and many liners had been laid up for their own protection lusitania however remained in commercial service in february 1915 to gain an advantage in the atlantic the german government stepped up their submarine campaign they declared the waters around the united kingdom and ireland a war zone meaning that ships would be sunk without warning in early march lusitania was approaching the coast of ireland from the west bound for liverpool on a 202nd crossing in the days prior the british admiralty had issued a warning to all shipping submarines active off the south coast of ireland as lusitania got closer the warnings continued u-boats active in southern part of irish channel last heard of 20 miles south of connemberg liked vessel the captain altered course keeping lusitania close to land in the belief that it would be safer assuming submarines would be more likely to keep to the open sea at 12 45 some miles south of lusitania's position a german submarine u20 surfaced on the lookout for potential targets before heading back to its home port at 1320 they spotted the funnels and masts of a liner so they dropped down to periscope depth and set an intercept course lusitania had no idea about the submarine's presence so continued on her passage believing her speed would keep her safe they didn't know that they were lining themselves up perfectly for u20 when the range closed to about 700 meters the sub fired a single torpedo which struck lusitania's starboard side right behind the bridge the explosion of the torpedoes quickly followed by a second much larger explosion from within lusitania herself within six minutes the folks all began to submerge and within 18 minutes the entire ship was underwater she was only 11 and a half miles off the old head of kinsale but it took several hours for help to arrive with a water temperature of only 11 degrees c it's 52 degrees fahrenheit chances of survival were slim out of 1266 passengers and 696 crew only 761 survived as it was a wartime casualty the entire truth about the disaster is a little hard to come by the british portrayed the lusitania as an unarmed passenger liner specifically targeted by a german u-boat others dispute this and say that lusitania was carrying a significant amount of undeclared munitions making her a legitimate wartime target in addition to her declared cargo there were claims of aluminium powder used in the manufacture of explosives as well as a large shipment of dairy products destined for the royal navy's weapons testing establishment that was too large to fit into lusitania's refrigerated hold either way as a wartime casualty the truth about the disaster will probably never be known what we do know however is that the sinking provoked outrage on both sides of the atlantic and acted to ghana support for the us joining the first world war only two years later

Channel: Casual Navigation

Views: 654,355

Keywords: casual navigator, marine, shipping, casual navigation, maritime explaination, merchant navy, sailing, marine animation

Id: EZJTMVwfuHs

Length: 10min 16sec (616 seconds)

Published: Fri Jun 24 2022