Settle a bet - River Thames

[okgo]

My mate insists that if you jumped into the Thames from say the footbridge by Waterloo station that you'd be dragged under and that would be the end of you

My argument is that is that you'd go down, come back up and then be able to swim to the side, why am I wrong?

[Reload]

Undercurrent? The water might flow faster the deeper you go.

[rhinochopig]

Surely depends on the strength of the tide, and where you jump from - tidal flow is strongest in the middle? Rowers fall in all the time and don't get sucked under.

[okgo]

Yes, maybe, but strong enough to stop a stong swimmer powering up through to the surface?

[TuxRacer]

Try it?

[Tow Vehicle Rqrd]

Would surely depend on the tide?

[Bugeyeandy]

Throw your mate in , if he lives you can be all smug that you were right.

If he dies then he'll never get to tell you how he was soooo right

Personally i'd say if you were sober and a half decent swimmer you have a pretty good chance of survival.

[stuttgartmetal]

Marchioness disaster night.
Police divers could not, or would not, enter the Thames that night, until high tide. The undercurrents aren't swimmable.

Bodies were found eight miles away, two hours later.
The currents in the centre of the river are un-swimmable, and you wouldn't make it.

One of the hoddies on a job in Battersea I was working at many years ago drowned half way trying to swim from one side to the other for a £50 bet.

If you fall in the river you must keep your head above water, and go with the flow till you reach the side if you ever fall in.
Never swimm against current.

Edited by stuttgartmetal on Monday 21st June 10:30

[rhinochopig]

The other issue would be water temp. At 0-4 degrees you've got about 15-30 minutes IF the cold shock doesn't make you unable to swim due to vaso-constriction or you involuntarily suck in water when your head goes under.

[Colin 1985]

Why would you be sucked down? There aren't any sinkholes in the Thames?

ETA: Like others say, Temperature might be the main issue, but I would have thought that any undercurrent would move horizontal, if there really is an undercurrent at all.

Edited by Colin 1985 on Monday 21st June 10:35

[okgo]

rhinochopig said:

The other issue would be water temp. At 0-4 degrees you've got about 15-30 minutes IF the cold shock doesn't make you unable to swim due to vaso-constriction or you involuntarily suck in water when your head goes under.

It's not that cold, people swim in it for fun a bit further up.

Stuttgart - fair enough, this is interesting.

[okgo]

Colin 1985 said:

Why would you be sucked down? There aren't any sinkholes in the Thames?

Well you'd be jumping from a pretty high bridge, so you'd go a fair way down on impact.

[rhinochopig]

okgo said:

rhinochopig said:

The other issue would be water temp. At 0-4 degrees you've got about 15-30 minutes IF the cold shock doesn't make you unable to swim due to vaso-constriction or you involuntarily suck in water when your head goes under.

It's not that cold, people swim in it for fun a bit further up.

Stuttgart - fair enough, this is interesting.

4-10 degrees only gives you 30-60 mins though.

[Colin 1985]

okgo said:

Colin 1985 said:

Why would you be sucked down? There aren't any sinkholes in the Thames?

Well you'd be jumping from a pretty high bridge, so you'd go a fair way down on impact.

But unless you planted yourself in the mud at the bottom you should float back up shouldn't you?

[okgo]

Colin 1985 said:

okgo said:

Colin 1985 said:

Why would you be sucked down? There aren't any sinkholes in the Thames?

Well you'd be jumping from a pretty high bridge, so you'd go a fair way down on impact.

But unless you planted yourself in the mud at the bottom you should float back up shouldn't you?

Without stating the obvious, this is the question I'm asking, and it would seem not tide dependant, so he has a point.

[Colin 1985]

Waterloo bridge looks quite high, perhaps the initial impact would cause some damage/knock you out.

[stuttgartmetal]

Colin 1985 said:

Why would you be sucked down? There aren't any sinkholes in the Thames?

The sinkhole that produces the currents are at the estuary.
The Thames is tidal right up to caversham.
The victorians were massively into land reclaimation, and narrowed the river, it used to be much wider, with a slower flow. Thats why it used to freeze over, but doen't now.

[okgo]

I think it stops being tidal at Teddington Lock.

There is a pub there called the tide end, afterall.

[rhinochopig]

okgo said:

Colin 1985 said:

okgo said:

Colin 1985 said:

Why would you be sucked down? There aren't any sinkholes in the Thames?

Well you'd be jumping from a pretty high bridge, so you'd go a fair way down on impact.

But unless you planted yourself in the mud at the bottom you should float back up shouldn't you?

Without stating the obvious, this is the question I'm asking, and it would seem not tide dependant, so he has a point.

It's all to do with laminar flow. IIRC it's possible for the river to be flowing at different speeds at various depths - I thinks this is down to thermoclines but could be talked arse there.

However, whatever the reason for the different flow rates, if your legs are in a faster flow rate than your upper body, you'll naturally get sucked under into the faster flow rate.

[louiebaby]

stuttgartmetal said:

The Thames is tidal right up to caversham.

False.

Fully tidal only up to Richmond Lock.