Crossing river fords

[glojo]

I have just watched old footage of cars being washed away in the Cornish village of Boscastle. What caught my eye was the level the cars were floating. The water was just about level with the lower door seals!

What that tells me is that if any of us get too adventurous when crossing a ford, we stand a very good chance of being washed away unless we carry extra ballast. Once the level of water rises above the level of the floor pan then my advice is to consider fitting a rudder or perhaps aborting the crossing?


Cap'n John

 

[jaymanek]

when was this flood John?

 

[GRAV888]

18th August 2004

 

[glojo]

18th August 2004

They actually had another flash flood last night which has once again damnaged the local shops.

Our local news showed the old footage and this time I paid more attention to the cars and vans that were floating along at very high speeds. It was worrying to see just how high they were out of the water. The amazing thing was that there were no fatalities.

Regards
John

 

[Dave Lewis]

We had flash floods in Bristol on Tuesday evening. The road I was on turned into a torrent within seconds, and a Micra ahead of me was beginning to float.
I headed for high ground.

 

[robert.saunders]

We had some severe downpours too, and again tonight - I would have headed for high ground but the nearest to me is Nottingham

 

[mark.t]

I have just watched old footage of cars being washed away in the Cornish village of Boscastle. What caught my eye was the level the cars were floating. The water was just about level with the lower door seals!

What that tells me is that if any of us get too adventurous when crossing a ford, we stand a very good chance of being washed away unless we carry extra ballast. Once the level of water rises above the level of the floor pan then my advice is to consider fitting a rudder or perhaps aborting the crossing?


Cap'n John

Hi john what we have to remember is that its not just water ...mixed in is everything that the water has washed down with it...spoil .. silt...rocks boulders tree trunks wheelie bins ...infac the entire contence of the village ....... + the force of the water which is being channelled through tight and narrow streets .....for instance when our thelmere aqueduct burst in walkden Manchester the amount of water was enough to cover the local Tesco's up to smutty mags on the magazine rack (top shelf) and car park but nothing got washed away (in car terms ) they just sat there and only moved slightly.......also when crossing a deep and fast flowing ford you are side on... so you have to 1 or more of 4 things ....1 make sure your water tight and have a rudder and population 2 make sure you can allow water in to give you ballast on the crossing 3 attempt if possible at an angle say 45 deg against the water to allow for drift ...4 don't cross

 

[glojo]

Hi john what we have to remember is that its not just water ...mixed in is everything that the water has washed down with it...spoil .. silt...rocks boulders tree trunks wheelie bins ...infac the entire contence of the village ....... + the force of the water which is being channelled through tight and narrow streets .....for instance when our thelmere aqueduct burst in walkden Manchester the amount of water was enough to cover the local Tesco's up to smutty mags on the magazine rack (top shelf) and car park but nothing got washed away (in car terms ) they just sat there and only moved slightly.......also when crossing a deep and fast flowing ford you are side on... so you have to 1 or more of 4 things ....1 make sure your water tight and have a rudder and population 2 make sure you can allow water in to give you ballast on the crossing 3 attempt if possible at an angle say 45 deg against the water to allow for drift ...4 don't cross

Hi Mark,
I think your missing the point.

These vehicles were indeed bobbing about like corks, but what caught my attention was the level at which they were FLOATING. It doesn't matter about what was in the water, be it rocks, beds, or even houses. These vehicles were floating and swept away, just because they were floating. The speed of the moving water made it spectacular, but they were NOT being pushed, they were like a raft going over the rapids. These vehicles were floating.

Taking your example, if the area is sheltered and the water rises, then hey presto, the vehicles will float, just like a ship in a dry dock, the ship and the cars will not move (apart from up-wards) In areas like the one you describe, there is not the huge sideways movement that you will have when crossing a ford. Forget my terrible example. Just think back to any disaster where cars try to cross a ford that is too deep. The car floats and gets washed downstream! They do NOT simply float and stay in the same position. They float away and gradually sink.

These cars, vans and 4 x 4's were all floating and the water level was round about the door seal area. In flooded areas the car will just become buoyant and perhaps loose traction. When crossing a ford however, the instant the car looses grip with the road then it becomes a boat and will be washed sideways into perhaps deeper water?

In the areas that just flood then vehicles can attempt to negotiate deeper water without the fear of being washed away. If you make a slight bow wave then just behind it you develop a trough and that helps keep the wheels on terra firma, BUT..... Once water rises above the level of the floor pan, you are at extreme risk of floating.... unless the vehicle is made of heavy metal, or leaks like a sieve.

Get an empty bucket or washing up bowl and float it in water. Note high high it floats, there is next to nothing under water. A car is a very light steel container and until it leaks, it is extremely buoyant.

Just my non scientific thoughts

John

 

[Sp!ke]

This is the way to do it. Takes a while to get started but worth the wait.

http://www.youtube.com/watch?v=mysp9FeOfd8

 

[grober]

eVERY LITTLE HELPS

Could this recent spate of extreme weather events have anything to do with global warming perchance? Oh no! I forgot for a moment that its all a sinister government plot to make us all pay more tax. Personally I blame TESCO's for paving over most of the UK with superstore carparks. EVERY LITTLE HELPS!

 

[television]

Yes I see what John means, the cars were parked along the road, the water only passed under them at sill level, many of the cars just floated away bobbing up and down like corks, even heavy ones like the Range rover went the same way, well they all did in the end.

It makes you think a little about driving at high speed in the rain, well it does for me

 

[glojo]

This is the way to do it. Takes a while to get started but worth the wait.

Absolutely brilliant. Reminds me of my driving course

What a pity they never filmed the driver after the crossing. Me thinks he would have been a picture.

Until the thing filled with water it was just the spinning wheels that got it back to solid ground, then it filled with water, great footage with brilliant sound effects.

Thanks for the link :bannana: :bannana:

Regards
John

 

[glojo]

many of the cars just floated away bobbing up and down like corks, even heavy ones like the Range rover went the same way, well they all did in the end.

It makes you think a little about driving at high speed in the rain, well it does for me

On a serious note, a simple bucket makes an excellent life saving aid. If someone gets into difficulties in the water, then an empty domestic polythene bucket will easily keep them afloat. I weigh eighteen stone and this type of bucket easily supports my weight, just because they are so buoyant.

John

 

[grober]

Eureka

I think that the Greek dude Archimedes http://en.wikipedia.org/wiki/Archimedes#_note-10
discovered this in the bath one day back in the first century BC. -- "A body immersed in a fluid experiences a buoyant force equal to the weight of the displaced fluid". http://en.wikipedia.org/wiki/Buoyancy
If on the other hand his Range Rover had been swept away in a flash flood it wouldn't have made such a good story.

 

[MBManInKen]

I weigh eighteen stone and this type of bucket easily supports my weight, just because they are so buoyant.

I think you'll find it's the air in the bucket that keeps you afloat .

 

[glojo]

I think you'll find it's the air in the bucket that keeps you afloat .

I think you misunderstood!

Inverting the bucket is a good way of keeping you afloat, but holding the bucket upside down is not that easy. Just make sure the bucket is empty then allow it to float. Grab it eitherside of the lip and try pushing down! Make sure you are in deep water though otherwise it's cheating. You will be amazed at how far out of the water you get attempting to try to push this bucket underwater. A very simple life saving aid that is so easily overlooked.

Holding it upside down is fraught with danger as the bucket will always try to invert.

John

 

[MBManInKen]

I think you misunderstood!

Inverting the bucket is a good way of keeping you afloat, but holding the bucket upside down is not that easy.

Ah, you fell into the trap .

Holding the bucket upside down would indeed be difficult, it's an inherently instable situation, asking for trouble .

The point is,when upright the bucket is not empty. It in fact contains air as well . There is a simple experiment you can do: replace the air in the upright bucket with water .

 

[glojo]

Ah, you fell into the trap .

 

[grober]

What you need is a bigger plastic bucket!

I prefer the larger plastic bucket myself. like HM minesweeper HMS Quorn

 

[glojo]

I prefer the larger plastic bucket myself. like HM minesweeper HMS Quorn

No doubt that will soon be one of the very few surface ships the Royal Navy will have?

John