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-alex-
11-24-2012, 03:12 AM
Hey guys.

How far could I realistically have a person (young female, and an average swimmer) travel down river (as in miles) in a rapid-river, with no life jacket, and survive? Shes taken an unexpected swim.

Thanks.

blacbird
11-24-2012, 03:44 AM
Temperature of water? Depth of stream? Rapids? A lot of variables come into play.

caw

veinglory
11-24-2012, 03:54 AM
If you are talking full on actual rapids that would involve staying upright, oriented and not exhausted for about 25 minutes--in conditions where a lot of people die in less than five minutes.

Just intuitively, I would have trouble believing it unless she has a floatation device. And even then she'd have to get lucky and not sucked into an undercut or have her head bashed against a rock.

If it is a more placid river then there are fewer hazards but she will be in there longer to get two miles. Maybe an hour. A lot of people would have trouble just floating unaided for an hour.

Drachen Jager
11-24-2012, 04:13 AM
Rapids tend to be fairly random. For instance, Niagra Falls has seen dozens of people go over, some on purpose, some by accident, the survival rate for those who have taken precautions is 50/50, those who have fallen by accident with no precautions have a survival rate of 50/50.

It's totally believable that a moderate swimmer could survive rapids, just as it's entirely believable someone with all the training and equipment in the world could die (as happened in the BC interior a few years back to a Search and Rescue tech who got tangled in her own safety line). Rivers are capricious things.

By the way, it's "river rapids" not "rapid-river".

veinglory
11-24-2012, 06:53 AM
It's not the surviving that causes me an issue. It's the traveling two miles and thus surviving quite that long.

Drachen Jager
11-24-2012, 06:59 AM
Surviving that distance depends only on water temp, speed of the river and hazards such as rocks. I remember swimming in a river near my grandparents' place when I was a kid where you went about 20 miles per hour over a flat stretch with no obstructions. You could easily do two miles of that, even in fairly frigid water.

veinglory
11-24-2012, 07:19 AM
20 miles an our would be astoundingly fast. More than 5 is considered an "expert" level rapids for kayaking.

blacbird
11-24-2012, 11:42 AM
I remember swimming in a river near my grandparents' place when I was a kid where you went about 20 miles per hour over a flat stretch with no obstructions.

I find 20 MPH hard to believe. Usain Bolt, at his best, runs not much faster than that. The velocity of the Colorado through the most violent rapids in the Grand Canyon is no more than 10 MPH.

caw

-alex-
11-24-2012, 05:29 PM
Thanks for the replies everyone.

Hm. Maybe rapids wont work then. Maybe I just need to have the river be fast flowing? The reason I say fast flowing, I assume the faster the water, the further shed go? Am I wrong in that theory?


Some variables; Idaho wilderness, May time of year. Cold water.

I guess I was asking for the furthest possible distance she might be pushed and it be believable that shed survive, really. Id planned to have somebody see her (not somebody who was with her) and manage to pull her out, but I wanted her to go as far as possible first.

melindamusil
11-24-2012, 09:27 PM
Here's another thought: what is her condition when she is pulled out of the water? If she's in cold water for quite a long time, I wouldn't believe it if she gets pulled out of the water, jumps to her feet (no injuries), and says "that was fun, can I do it again?"

On the other hand, if she's unconscious/barely conscious/needs CPR, to me that is more believable. At the very least she's got to be shaken up pretty good. I second Drachen Jager - rivers are very random and so is survival.

You might want to consider water levels. I've done some white water rafting in Colorado, which wouldn't be *too* different from Idaho. The water is very cold, of course (it's melted snow from the rockies). I recall learning that low water levels are actually riskier because there are more rocks exposed. So the same stretch of river might be relatively easy to navigate in a year with lots of precipitation, and very dangerous in a drought year.

Another thought - what are the circumstances that led to her taking a swim? One of the first things they teach you about white water rafting is that if you are thrown overboard, you should turn your body around so your feet are facing downriver (and thus your feet will take the brunt of anything that you might run into). If she doesn't take any hits to the head (whether because she turned her body around, or because of dumb luck), I find the situation much more believable.

espresso5
11-24-2012, 09:31 PM
If she's capable of staying afloat without a life jacket, she would be able to make it to the edge of a river on her own.
Most people drown in moderate rapids (even if it's not very deep) because they get a foot caught in something and exhaust themselves trying to keep their head above water as the current pushes them down. A slower current wouldn't cause this problem.
Temperature is probably the biggest factor in your scenario. If the river has snow melt from the mountains, it could be pretty cold.

Drachen Jager
11-24-2012, 09:37 PM
I find 20 MPH hard to believe. Usain Bolt, at his best, runs not much faster than that. The velocity of the Colorado through the most violent rapids in the Grand Canyon is no more than 10 MPH.

caw

Rapids slow the river down, the more violent, the more they slow it down, that's pretty obvious physics there, all that churning around, it's like comparing a driver doing a slalom to a driver going straight. Many rivers go faster than 20mph over smooth stretches.

Apparently (according to Wiki Answers) one of the fastest rivers in the world goes 70 MPH in flood stage.

Like I said, this was a smooth portion of the river.

-alex-
11-24-2012, 10:06 PM
Here's another thought: what is her condition when she is pulled out of the water? If she's in cold water for quite a long time, I wouldn't believe it if she gets pulled out of the water, jumps to her feet (no injuries), and says "that was fun, can I do it again?" On the other hand, if she's unconscious/barely conscious/needs CPR, to me that is more believable. At the very least she's got to be shaken up pretty good. I second Drachen Jager - rivers are very random and so is survival.
This is exactly it. She's barely conscious when she's pulled out. And then passes out altogether. The story is told in 1st Person, the next scene is when she wakes up, medical care already been given.



Another thought - what are the circumstances that led to her taking a swim? One of the first things they teach you about white water rafting is that if you are thrown overboard, you should turn your body around so your feet are facing downriver (and thus your feet will take the brunt of anything that you might run into). If she doesn't take any hits to the head (whether because she turned her body around, or because of dumb luck), I find the situation much more believable.
Long story as to why, but she was being chased, and slipped down a high cliff-y bank, unable to stop herself from sliding, falls into the cold water, and is dragged by the current.

melindamusil
11-24-2012, 11:27 PM
Long story as to why, but she was being chased, and slipped down a high cliff-y bank, unable to stop herself from sliding, falls into the cold water, and is dragged by the current.[/QUOTE]

One thing I like about this - it explains why she doesn't have a life vest or some sort of flotation device, since it'd be pretty unusual for her to get in a raft/canoe/kayak without a life vest.

blacbird
11-24-2012, 11:59 PM
Some variables; Idaho wilderness, May time of year. Cold water.

The principal problem will be hypothermia. That water will be cold, for sure, and water only runs fast when there's a high stream gradient, which pretty much guarantees there will be rapids. Much of Idaho is mountainous, especially the wilderness areas. Google Earth may help you a bit here.

But hypothermia sets in very quickly in cold water (matter of minutes), incapacitates people trapped in it, and that often leads to drowning. I don't think your character manages to survive miles downstream, unless extremely lucky.

caw

WeaselFire
11-25-2012, 04:44 AM
From personal experience, I can be swept just under three miles down a moderately quick river gorge (no access for exiting water) in not much more than half an hour. Warm day, water was in the 70 degree range and I was cold and exhausted when I managed to get out. My partner was ahead of me and couldn't get back to me but had caught my kayak. He was at the beach where I was able to get out and and tossed me a line.

I had a vest on though, floated mostly on my back feet first and was able to keep away from the boulders and other death traps. I fell out in the rapids but most of the trip was free of turbulence. This was supposedly class 3 water that we later learned was class 5 due to the dam upstream releasing water. We were stupid, but survived. Kind of the story of my youth. :)

Jeff

blacbird
11-25-2012, 08:42 AM
From personal experience, I can be swept just under three miles down a moderately quick river gorge (no access for exiting water) in not much more than half an hour.

Which math works out to 5-6 MPH.

In relatively warm water. In really cold water, hypothermia can debilitate in as little as ten minutes.

caw