The Threat Below

Bill Sweetman on the latest advances in submarine technology:

Modern diesel-electric submarines (SSKs) are very hard to detect. It’s not that SSKs with air-independent propulsion (AIP) systems are much quieter, but they mitigate the SSK’s drawback: lack of speed and endurance on quiet electric power. When the Swedish AIP boat Gotland operated with the U.S. Navy out of San Diego in 2005-07, the Navy’s surface ships turned up all too often in a photo album acquired by the submarine’s mast. The sub was so quiet, that it consistently managed to get within easy torpedo range.


AIP—which uses stored liquid oxygen and fuel to generate power underwater—seems to be here to stay, whether it uses the Swedish-developed Stirling-cycle engine (a 19th-century curiosity, but very efficient) or fuel cells, favored by ThyssenKrupp’s German yards. and Russia. Lithium-ion batteries will further increase underwater performance. Kockums advertises another step in invisibility called Ghost (genuine holistic stealth) which, like stealth technology on an airplane, involves the careful blending of hull shapes and rubber-like coatings to make the submarine into a weak sonar target. .

Other improvements are making the submarine more elusive and lethal. Masts with high-definition cameras are as clear as direct-vision optics—so the mast needs only to break the surface and make a single sweep to provide a full horizon view. Finmeccanica’s WASS division and Atlas Electronik offer modern all-electric torpedoes with multiple guidance modes, from fiber-optic to wake-homing, and back-breaking influence fuzes that work too often for comfort.

As I've written here before, maritime trading nations that can't protect their sealanes don't remain trading nations for long.