21 Dec 2010, 21:22
The idea is to use an inflatable rubber boat that is long enough to accomodate one person lying flat on his back. It would be covered with a rubber or pvc sheet that is attached to the bottom of the boat from the outside and there should be a breathing tube of course. The operation would be as follows: The person enters the non-inflated boat, underneath the sheet, puts the breathing tube into a suitable position and then starts an electrical pump to inflate the boat.
In theory, the sheet is large enough to cover the flat boat and will stretch a bit to accomodate the victim. When the boat is inflated, the walls will rise and pull up the sheet. The sheet can't go up, because there is no air getting inside. The air which is trapped a
eady, will be thinned, and while the air pressure outside is higher, it should go up, i.e. along the walls of the rubber boat. And when there is no air around the victim, the sheet will enclose him completely and hold him tight against the floor of the boat (we could add a mattress for comfort, an air-mattress with a little bit of air should expand too). There is one thing that this method is based upon: The flat walls have a length x, which is the overlapping length of walls and sheet. Once the walls are inflated, they will first have a circular cross section, wich has exactly the circumference of 2 times X and the sheet will cover 3/4 of that, which is 1.5x - the sheet widith has to expand by 0.5 times X because there is no air between sheet and boat, and therefore the sheet has to stay close to the boat. Of course, the air will expand a bit and this might be compensated by further inflating the walls, which then will have a circumference that is larger than 2 times X. And as soon as the walls are higher than the victims body, their tops are the highest points and the air should theoretically go there, leaving void, nothing, no space between victim, boat and sheet anywhere else.
This scenario is highly hypothetical, and I am not sure if it would work as expected. A rubber sheet might expand too much, while pvc might be too rigid. And perhaps the idea of the air gathering at the top of the walls is wrong.
I don't have a rubber boat, buying one, plus the sheet and an electrical air pump might be even more expensive than a vacuum bed, but the whole thingy would be completely innocent, if not in use and could be stowed away in a relatively small place. What do you think, how likely is this idea to work?
An obvious alternative would be an inflated rubber boat with a sheet cover and a vacuum pump sucking out the air inside. But the vacuum might have to be applied in several places at the same time, to make sure that it gets all trapped air. And the vacuum has to be maintained, the pump would have to run all the time.
Release: The hose from pump to boat should be removed and hopefully, the boat doesn't have a one-way valve (an exsting one could be disabled).
I made a drawing showing the cross section of the boat plus sheet, inflated and flattened:
In theory, the sheet is large enough to cover the flat boat and will stretch a bit to accomodate the victim. When the boat is inflated, the walls will rise and pull up the sheet. The sheet can't go up, because there is no air getting inside. The air which is trapped a
eady, will be thinned, and while the air pressure outside is higher, it should go up, i.e. along the walls of the rubber boat. And when there is no air around the victim, the sheet will enclose him completely and hold him tight against the floor of the boat (we could add a mattress for comfort, an air-mattress with a little bit of air should expand too). There is one thing that this method is based upon: The flat walls have a length x, which is the overlapping length of walls and sheet. Once the walls are inflated, they will first have a circular cross section, wich has exactly the circumference of 2 times X and the sheet will cover 3/4 of that, which is 1.5x - the sheet widith has to expand by 0.5 times X because there is no air between sheet and boat, and therefore the sheet has to stay close to the boat. Of course, the air will expand a bit and this might be compensated by further inflating the walls, which then will have a circumference that is larger than 2 times X. And as soon as the walls are higher than the victims body, their tops are the highest points and the air should theoretically go there, leaving void, nothing, no space between victim, boat and sheet anywhere else.This scenario is highly hypothetical, and I am not sure if it would work as expected. A rubber sheet might expand too much, while pvc might be too rigid. And perhaps the idea of the air gathering at the top of the walls is wrong.
I don't have a rubber boat, buying one, plus the sheet and an electrical air pump might be even more expensive than a vacuum bed, but the whole thingy would be completely innocent, if not in use and could be stowed away in a relatively small place. What do you think, how likely is this idea to work?
An obvious alternative would be an inflated rubber boat with a sheet cover and a vacuum pump sucking out the air inside. But the vacuum might have to be applied in several places at the same time, to make sure that it gets all trapped air. And the vacuum has to be maintained, the pump would have to run all the time.
Release: The hose from pump to boat should be removed and hopefully, the boat doesn't have a one-way valve (an exsting one could be disabled).
I made a drawing showing the cross section of the boat plus sheet, inflated and flattened:
