Originally Posted by
meleagertoo
Shaped charges most assuredly must NOT be in direct contact with the target. They require a standoff distance related to a multiple of the width of the charge as per the individual design. In the case of a custom-made charge built into a boat it could be a vary wide device ndeed - say a metre. A 5 times standoff distance would be at peak effitiveness at 5m, about the height of the bridge I'd guess, and such a charge laid along a boat is in the perfect alignment to sever a structure like a bridge from edge to edge.
In any case a sufficiently large in a boat under a bridge is simply going to lift it up in the air and let it drop or with enough brisance simply shatter the concrete. The blast pressure will be 'loosed' (sic) in all directions, but the water will tend to reflect much of it upwards where you want it.That'd do the job too.
If you imagine a ton or more of explosive is defeated by a 20ft airgap or only leaves a 'crater' the size of a vehicle you are way, way off the mark.
The lack of obvious scarring suggests a blast from below which had the added effect of projecting debris upwards to puncture the tank-cars.
No way was this air delivered or the defences would have lit up like Novemner 5th.
A shaped charge designed to sheer metal needs to be in contact with the metal, a directional shaped charge for penetrating an object can be set up with an air gap. However what you / others are suggesting is that they used a shaped charge to fire vertically along the full width of the bridge to sheer the steel and fragment the concrete to allow it to fall back in upon itself. The length of the boat would therefore have to be the width of the double roadway, at the optimum distance from the underside of the bridge, taking into account tides, waves and wind to be close to 90 deg to the bridge.
However if it was suggested that it was a BFOB, (Big F Off Bomb), then that isn't a shaped charged and that is more plausible.
There were suggestions that there were multiple air strikes (incl MLRS) yesterday evening so perhaps a missile did manage top get through, especially as the air defences were already lit up like Novemner 5th (sic).
After all the Moskva was sunk by missiles that were supposedly not able to do their job against a guided missile cruiser.
Fanciful the idea may be, but the idea of a Ukrainian boat travelling such a great distance without being spotted also takes a leap of faith.
Time will tell and there is little point in willy waving when the facts are extremely limited.