How do depth charges work? Are they still used on modern ships?
I thought it might be on howstuffworks.com, but it isn’t. Basically, a depth charge uses an adjustable pressure sensor to trigger the detonation. Since the pressure changes with depth very predictably, it’s easy to set the charge to detonate at a given depth. I don’t know if they are still used, but I don’t see why not.
Depth charges had pressure sensitive fuses. The pressure at a certain set depth would detonate them.
They aren’t used any more. ASROC is the ship borne anti-sub weapon of choice now I think.
The depth charge creates a high pressure wave on the hull of the submarine, rupturing seams causing internal flooding.
Depth charges are no longer carried by surface ships, though there are still depth bombs that can be carried by aircraft. Even ASROC seems to be carried only by the Spruance class destroyers and possibly Ticonderoga/Bunker Hill cruisers. The newer Arleigh Burke class of destroyers seems to have only ship-launched torpedoes as an antisubmarine weapon. Most of the antisubmarine role in modern navies is performed by helicopters and land-based aircraft (and other submarines).
Many WWII-era depth charges used hydrostatic (pressure-sensitive) fuses, but there were also magnetic fuses that were triggered by the metal hull of a submarine. The ‘ashcan’-shaped depth charges that were rolled off the back of a ship or shot off the side by an explosive charge were eventually replaced by teardrop-shaped charges and by antisubmarine mortars (like ‘Hedgehog’) that fired ahead of the ship. (Such mortars were used in the Soviet/Russian navy at least up to the end of the Cold War.)
My dad chased Soviet subs around the time of the Korean war and according to him what depth charges were really useful for was to prevent a sub from firing a torpedo and/or destroying the sub when it tried. If the submarine opened a torpedo tube (whatever it is called), it was at risk of having a depth charge going off in the vicinity. If this happened, the torpedo would be slammed backward into the sub, hopefully causing catastrophic damage. This risk could effectively negate the offensive capability of the submarine.
ASROC has been largely replaced by a variant, Vertically Launched ASROC (VLA).
This is an ASROC that can be loaded into the vertical launchers of an AEGIS ship, namely Ticonderoga cruiser or Burke class destroyer. ASROC, or antisubmarine rocket, works by firing a missile at a datum, or suspected sub location. The missile then breaks up and drops an active homing torpedo into the water.
These ships carry regular torpedoes as well.