Don’t toss around distances like “100 ft” so lightly. 100 ft of horizontal distance is a trivial construction effort. a 100ft vertical habitation is almost as easy, today, but was a world-class construction effort not much more than century or so ago, when the definition of “skyscraper” was set at 5 stories. 100 feet down underwater? There are only a handful of permanent fixed 1 atm “shirtsleeve environment” habitable structures at 100 or 200 feet in the world.
The Aquarius underwater coral research lab in the Florida Keys National Preserve is only at 62 ft depth, airlocked and sealed at substantially less than ambient water pressure, but a return to the surface still requires 17 hours of decompression. At 100-200 feet, you’re pretty much talking about a) submarines (pricey and nowhere near the size of a tunnel); b) structures sealed in bulk concrete, like tunnels; and c) structures like submarines and underwater habitats that require medical vetting to enter, monitoring to remain in, and decompression to safely exit
100 ft down can easily kill an experienced diver in full scuba gear, if s/he doesn’t follow all the rules – and the main danger lies in the effects of pressurization, not the water
Actually, there’s nothing particularly infeasible about a Bering Strait bridge or tunnel. The problem is that each side of such an entity would be about 2000 miles from the nearest usable railhead, through extremely inhospitable landscapes. Even the US / Canada highway system falls several hundred miles short of Nome, and there’s nowhere near the capacity on that to make a trans-Bering link viable. Between North America and the Far East, it’s much more cost-effective and time-effective to transport bulk goods via ship, and people via plane.
The Folkestone-Calais Chunnel links two densely-populated countries with appropriate infrastructure (well, at least once the UK side has the high-speed link to London in operation); a trans-Bering structure would start in the middle of nowhere, and end in the middle of nowhere, 50 miles – and a continent – away. The very epitome of a white elephant.
Not quite the same, but too cool not to mention: at either end of the Corinth Canal in Greece, there are bridges that sink under the water to let ships pass.
Apart from that I just don’t understand why an underwater bridge would be useful, it sounds like you’re saying ‘partial buoyancy’ is some state in which a body will just hover at some point under the surface of the water, neither sinking or floating. This is really hard to achieve in laboratory conditions - in an ocean, it would be impossible and would be really susceptible to perturbation anyway.
How would this be advantageous to a submarine? You’d be putting a LOT of force on the teather, if that was the sole means of guidance. Since this means you’re going to have to put a means of turning this thing to keep the forces from snapping the teather, it might as well be designed to not use one.
Are you implying that the teather would be somehow powering the vessel, similar to a cable-car? That seems even less viable, having an electrically powered cable underwater. Unless I misunderstood your statement?
Yet South African gold miners can descend 3.3 km into the earth’s crust. And the Chunnel is on average 150 feet below the sea bed: Chunnel
I don’t see why a floating “tunnel”, or a submerged and embedded tunnel would be any different since both ends would be exposed to the surface air pressure.
Well I posted it just to consider six minutes later, “Oh yeah, well that will fine up to the point where you run into a whale.” :smack:
But I imagine that the advantage of a tether would be that you could make the craft longer. It would also be a chance to test out some materials for the space elevator and whatnot (assuming you consider that as being an advantage.)
