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> In 2005, the nuclear-powered USS San Francisco collided with an underwater volcano, or seamount, at top speed, killing a crew member and injuring most aboard.
by dataflow 3y ago
> In 2005, the nuclear-powered USS San Francisco collided with an underwater volcano, or seamount, at top speed, killing a crew member and injuring most aboard. It happened again in 2021 when the USS Connecticut struck a seamount in the South China Sea, damaging its sonar array.
How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Why are light, radar, and sonar still not enough to detect obstacles that big?
- miketery 3y agoMaybe they’re off for stealth?
- vkou 3y agoYou can't navigate by light, and if you are trying to be stealthy, you won't be running active sonar. Radar doesn't work well underwater.
- perfmode 3y agohow deep do submarines cruise?
- dragonwriter 3y agoThe San Francisco collided with the seamount at 160m depth.
- dragonwriter 3y ago> How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Seamounts don’t give off active emissions (except maybe if they are erupting), and subs usually use passive hydrophones (which rely on the active emissions of targets), not active sensors when operating underwater to avoid detection. Navigation is done by charts using inertial navigation alongside dead reckoning. Hitting a mountain is generally because the mountain wasn't on the chart being used, though in principle in could also be due to an error in positioning (with inertial navigation, that should be much rarer than with dead recknoning alone, but its not impossible.) (In the case of the San Francisco, for instance, other charts had a notation of "discolored water" which suggested a probable seamount, which the investigation noted should have been transferred to the chart in use, but was not.) > Are light, radar, and sonar still not enough to detect obstacles that big? Radar is useless underwater, light would also be useless for spotting anything in time to react at speed, and sonar isn’t routinely used because it compromises stealth.
- throwaway8503 3y ago>> Are light, radar, and sonar still not enough to detect obstacles that big? > Radar is useless underwater, light would also be useless for spotting anything in time to react at speed, and sonar isn’t routinely used because it compromises stealth. Any people with knowledge in the field care to comment on whether it's feasible for a light (em?)-type, active, near-range detection system to work? It seems to me the basic problem is: - enough energy to get a signal at a range sufficient to move around any detected obstacles - high enough dissipation in water to minimize range at which detection by external sensors is possible
- iancmceachern 3y agoThe light transmission through the water, it's cloudiness, is just way to variable for something like this to work constantly, reliably.
- throwaway8503 3y agoWouldn't the cloudiness itself be a signal? Presumably it's essentially clear of suspended particles, most of the time.
- iancmceachern 3y agoA signal of what?
- throwaway8503 3y agoSomething solid ahead To clarify: I mean that, generally speaking, the presence of 'cloudy' water would presumably signify that the seafloor was close. In the open ocean, maybe a sea mount is surrounded by essentially a cloud of particles. Edit: I think your reply made the thread reach maximum depth, so I'll end it here.. I should do more reading on the topic.
- 3y ago
- gonzo41 3y agoMost underwater travel is done via dead reckoning. Like flying a plane with no windows. You're only as good as your maps and instruments.
- mywacaday 3y agoHow viable would drones travelling in front of the sub like the whiskers in the TV show seaQuest DSV
- capableweb 3y agoOne of the main features of military submarines is being undetectable by others, to various degrees. This include visual, audio and movement detection. Drones would probably make all of those three factors worse and make the submarine more detectable, than without a drone travel in front.
- hilbert42 3y agoThe USS San Francisco crash-type problem was discussed some while ago on HN. At the time I questioned how this could happen when one would expect a submarine of that sophistication to be equipped with both sonar and gravity detection. Detecting changes in gravity is common practice in mining surveys (ores often have higher densities) and geological work, so for me why the sub collided with the seamount remains a mystery. I cannot believe subs of this class don't have such detection on board so could someone more knowledgeable about the subject than me provide an explanation.
- deleted 3y ago[deleted]
- DrBazza 3y ago> How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Two things: first US submarine, second "South China Sea". I suspect the sonar was off "for reasons".
- nahnahg 3y agoBecause they are too stupid to use large aperture (and pressure stabilized) plain old optics with CCD sensor array. I assume this is done actually. If fish can do it at the greatest depths then...
- indymike 3y agoEasy way to not be found is to not emit energy be it sound, heat, light, radio frequency, etc... until we discover a passive sensor that works underwater that can see static objects that may not emit energy, seamounts and other things that change the map are occupational hazards for submariners.