[HN Gopher] The Grand Unified Theory of Rogue Waves
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The Grand Unified Theory of Rogue Waves
Author : theafh
Score : 72 points
Date : 2020-02-05 17:56 UTC (5 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| jschwartzi wrote:
| Does this have anything to do with Markov Chains? Because it's
| smelling like that type of problem.
|
| The verbiage in the article is a little too "wanky" for me to
| tell.
| gshubert17 wrote:
| > [a better model] paving the way for machinery that could, for
| instance, scan the ocean and notify ship captains that they face
| a 13% chance of running into a 30-meter wave in the next 15
| minutes.
|
| What sorts of actions would captains take under these
| circumstances? Rogue waves are so large and powerful--would any
| action be enough to prevent losing a ship?
| eloff wrote:
| You'd want to orient the ship to hit it bow first probably,
| rather than on the side where it could roll or punch a hole in
| the ship. But what Captain in a serious storm is not going bow
| first through the waves anyway? I don't know much about the
| industry, so that's an honest question - maybe deadlines and
| route optimization still plays a role and they will often sail
| at an angle to the waves, I doubt they would ever sail near 90
| degrees in any case, but maybe you could change a 30 degree
| angle to closer to 0 if you had warning.
| btilly wrote:
| _You 'd want to orient the ship to hit it bow first probably,
| rather than on the side where it could roll or punch a hole
| in the ship. But what Captain in a serious storm is not going
| bow first through the waves anyway?_
|
| Hitting the swell bow first will not necessarily help you.
| See https://www.youtube.com/watch?v=A2KqofR05TE for a video
| of a boat actually hit by a rogue wave. They are riding the
| swell correctly - but the wave hits from the side.
|
| Note that a swell and a current are known conditions that
| make rogue waves more likely. And it is not uncommon for
| rogue waves to be moving in a different direction than the
| swell.
| eloff wrote:
| Someone else also commented that it won't save you if the
| wave is big enough. I'm not contesting that. I'm just
| saying that gives you your best chance.
| slavik81 wrote:
| If the wave is big enough, bow-first won't save you.
|
| If you go over the wave, half your ship ends up cantilevered
| over the peak. A ship isn't built to hold half its weight in
| the air like that. It will break.
|
| If you go through the wave, the upper decks get hit by a wall
| of water. The windows blow out, the bridge is destroyed, the
| computers are toast and the ship is swamped.
| irrational wrote:
| All that is left is to go under the wave.
| gamegoblin wrote:
| FWIW, this is exactly what surfers do ("duck diving").
| eloff wrote:
| Agreed, that if the wave is big enough you're toast anyway,
| but bow-first still gives your best chance as I understand
| it. So if you had warning you'd want to get your crew into
| less vulnerable positions where they can evac more easily,
| and ensure you're facing bow-first into the waves.
| HenryKissinger wrote:
| Force shields it is then.
| i_am_proteus wrote:
| It's absolutely normal to steam with little regard to wave
| direction in mild seas. Merchant ships typically follow great
| circle routes with as little deviation as possible.
| eloff wrote:
| Right, but in a serious storm?
| mark-r wrote:
| I think the point of a rogue wave is that it can form
| even when there's not a storm. They seemingly come out of
| nowhere.
| eloff wrote:
| Not really, they're still proportional to the average
| wave height. So while you could always be at risk for
| rogue waves, the sea has to be quite rough before a large
| vessel need be worried about them.
| mark-r wrote:
| I didn't see anything in the article that implied the
| rogue waves were proportional to the average. In fact the
| thing that makes them rogue is that they are many
| standard deviations away from the average.
| eloff wrote:
| This is not the first article I've read on the subject,
| it's my understanding that rogue waves are built from
| regular waves, therefore they're proportional - just many
| standard deviations away as you say. You can get a 20
| meter wave in the midst of 10 meter waves, but you're not
| going to find that in 2 meter waves, rounded to an
| appropriate number of decimal places.
| andrewflnr wrote:
| You could make sure all your people are awake and ready to get
| in the lifeboats if the ship breaks up. Definitely make sure no
| one is way down in the hold where they'll drown before they get
| on deck.
| [deleted]
| tkahnoski wrote:
| Batten down the hatches.
|
| Or maybe a herd strength thing where one ship detects and can
| send out an alert for others to redirect around the path.
| ishtanbul wrote:
| this seems like an insurance problem, rather than a technical
| one. rogue waves appear to be rare enough that spending money on
| prediction or detection might outweigh the cost of simply
| insuring against catastrophic loss
| HeyLaughingBoy wrote:
| Tell that to the people on the ship that it happens to!
|
| Granted, it's usually survivable. Decades ago a friend of mine
| on a containership experienced a rogue wave with no more harm
| than being terrified by "either the last thing I was ever going
| to see or the most majestic thing I'd ever see" but it doesn't
| always end that way.
| btilly wrote:
| It is both.
|
| Ships used to be built to the largest waves that were
| conceivable. We underestimated the forces in a rogue wave by a
| factor of more than 5. Ships today are built stronger, we are
| careful about seas where rogue waves are more common, and
| insurance now knows to take rogue waves into account in their
| policies.
|
| Better predictions as well would be good.
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