Is it true (or an urban myth) that a swimmer would be sucked under (presumably to drown) when a capital ship sinks?
- posted
8 years ago
Is it true (or an urban myth) that a swimmer would be sucked under (presumably to drown) when a capital ship sinks?
Myth
Like toilet bowl water swirls.
I would think so. I was in a 6-man rubber raft that went over a small falls and under water and though I wasn't tied to the raft, I went under water too. How much more so with a big ship.
Something about traveling and being on my own made me fearless however and I confidently waited, with my eyes open iirc, until I popped up again a few seconds later. Without the raft.
This was the Dranze River in France, just east of Geneva, Switzerland.
I don't think the swirl is the part that matters. If you pour a half-bucket of water in a toilet, it will drain without swirling. It's the draining and emptying that matters.
Basic fluid mechanics. You know that the swirl direction of opposite of Southern hemisphere. CCW and CW. Rotating earth.
Hog wash about toilets...
Didn't take physics in H.S. or college? Wondering.
I certainly took enough physics classes to know the direction of the nozzles and shape of the bowl has more effect on the swirl than the weak Coriolis effect
In panic, someone might not hold his breath, and even more likely, he might not take a big enough breath to be able to hold his breath for long, but I would think if one does get a big breath and doesn't panic, he should be able to hold it easily long enough to come to the surface again.
Does it depend on how fat he is how fast he surfaces? Probably. So if you anticipate being on a sinking ship, try to gain weight first. (When my brother was in Viet Nam during the war, my mother wanted him to gain weight to tide him over if he was taken prisoner. He didnt' go on patrol and he wasn't a flier, so the odds were very slim he would be taken prisoner, but other than that, I think she was right. )
So I've heard.
Hmm. This post is not in reply to my reply to you where I took issue with the importance of swirling. But I'll answer anyhow.
I'm not doubting that water in toilets swirls, or that water in eddies swirls. I'm saying that swirling water has nothing to do with sucking someone in behind a sinking ship.
In fact the water probably isn't swirling. The forces that make water swirl, in a bathtub for example, are weak compared to the tremendous amount of water that surrounds a large sinking ship. If the ship were not sinking, there would be no swirling, and I don't think sinking an inch every minute is enough to permit or cause swirling.
It's when the weight of the ship and the water it now contains is greater than the weight of the water the whole ship displaces that sinking quickly begins, and at that point there isn't time enough before the ship has totally sunk for substantial swirling to begin. Perhaps not any swirling at all. Note that it takes quite some time to have it begin even in a bathtub.
The stage of sinking slowly can take hours, but when sinking quickly begins, it takes no more than a minute, maybe two.
To beat this to death, I think the thousands of times people get to watch water go down a sink drain overhwhelms their lack of experience with sinking ships. However one can drop or throw rocks in a lake or a river pool, off a pier for example, and see that there is no swirling.
(One could even attach small balls that float to the rock, with some weak "adhesive" that fails when wet, and time how long it takes the balls to return the surface. Varying the depth of the water, or the release time of the "glue", one could measure three data points and extrapolate to a ship and a person, and a person with a life vest.
(Or maybe one doesn't need the rock for all of these experiements. While the water falling into the opening would slow down resurfacing, that water has filled in the hole within a measurable number of seconds, and the real question is, What is the acceleration of a human of given weight and size due to buoyancy, and how long would it take to stop downward travel and cause upward travel, and what would the total time be? All but the downward speed could be extrapolated just from measurements made by releasing floating balls from an underwater device.)
The notion that water behaves differently in northern and southern hemisphere basins is a nice little earner for smart operators living on the equator. In reality, the direction in which the water goes down the plughole is determined by several factors, such as the shape of the basin, and the way the water is moving before the plug is removed, etc. The position of the equator has no effect at all. There are manufacturers in equatorial countries who make basins in 3 shapes, one for north of the equator, one for south and one for right on the equator. The aforementioned smart operators buy these basins and set them up at appropriate places, and charge gullible tourists to watch the water going down the 3 plugholes in what they imagine to be a geographically-determined way.
Andrew Dickens, Bexhill-on-Sea UK
(The funniest explanation I've seen.)
Hey, couple months ago whale watching boat rolled and sank hit by a big wave West of Vancouver Island, few died and some survived. A couple survived is from Calgary here. They both said they got sucked under and then surfaced. My 2nd uncle is life time Navy man, Captain(ret), ROKN. He said same thing.
Mythbusters tried it, and concluded that there was no significant sucking sown.
Sylvia.
I heard abou tthat.
I didn't hear about that. Good to know. Should make OP happy to know too.
Just remember to pretend you're in the doctor's office, suck in a big breath and hold it.
So when ship is abandoned, crews jump off the ship, they hang around the sinking ship, right? They always swim away from the ship as much as they can. Ask any sailors.
I think there was a TV show where a kid called a lot of people in places like Australia, to ask them which way the water swirls when they flush.
A toilet bowl is too small to show the Coriolis effect, but a pool isn't according to Sandlin and Muller.
A toilet bowl is too small to show the Coriolis effect, but a pool isn't according to Sandlin and Muller.
Nice find! Will a Sinking Ship Suck You Down with It? | MythBusters
Theory 1: Air mixes with water makes the water less dense, hence sucking you down. Theory 2: Cavities in ship causes water to rush into the ship, hence sucking you down. Theory 3: Ship falling down creates a vortex above it, hence sucking you down.
That's rather circular.
There is a wide spread belief that one can get sucked down, and there's no reason to think sailors have any better knowledge of this than anyone else - it's hardly something most will ever experience - consequently one would expect them to swim away.
Anyway, sucking people down is not the only possible hazard represented by a sinking ship.
Sylvia.
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