quote:

Originally posted by mikeyspizza:
In 2005, the USS San Francisco ran into an undersea mountain at flank speed.

Luckily they had a tarp with them so they could patch that and get back to port.

^^^^
Man the fact that that boat took that kind of hit and didn't stay at the bottom is pretty impressive.

And I always wondered how they navigated when they were under. How long do they stay under at a time?

quote:

Originally posted by bubbatime:
How do submarines navigate the oceans without running into under ground mountain ranges and shallow water?

One thing is certain. They don't use my wife.

Voyage Management system- VMS, utilizes digital charts with other external sources (NavSat & GPS) fed in, to establish the boats position. Plot information is also periodically entered manually in establishing a high quality fix or position.

quote:

Originally posted by ARMT Guy:

quote:

Originally posted by mikeyspizza:
In 2005, the USS San Francisco ran into an undersea mountain at flank speed.

They eventually got that boat back in service, ( well, at least it ran and could submerge some, ) but mostly for PR purposes.

A nose graft can do wonders.

The seamount wasn't on the charts, the captain got canned for lack of procedures, while a few others also got reprimanded. There was quite a few heroes on board her during that accident. You can see a few ripples in the hull plates as you look further aft.

She got a new bow section from the recently retired USS Honolulu. Eight years after the accident, she is now retired as a moored training ship in Charleston.

quote:

Originally posted by Pipe Smoker:

Plus SONAR?

Underwater mountains aren't going to ping your sonar. Sonar is for passive listening. If you go active, might as well just shout, "Here I am!" Passive sonar is used to triangulate which direction and how far from the sub is all the sound sources. There's a sonar array in the nose of the sub and you can let out a sonar ball some distance from the back of the submarine.

I forget what they're called but they used Gyroscopes. I think someone above is correct is calling them Inertial Guidance System. It tracks from a specific reference on the map all the vectors the submarine has undergone.

To calibrate, I'm sure the submarine can float an antenna that breaks the water surface and calibrate using GPS.

I don't have actual direct knowledge just what I can piece together from working on submarine electronic systems such as sonar.

Inertial navigation systems. These are aided by many other types of sensors. Doppler velocimeters, screw speed sensors, electro magnetic speed sensors, GPS on the surface etc.

INS.

Tanks (I imaging most combat vehicles) have an inertial navigation unit. Once it is aligned it can tell the relation of the vehicle to the earth and even the turret to the hull. Useful for lots of things. Never thought of applying it underwater. Makes sense.

Having stood a number of Sonar watches on a surface vessel (30+ years ago), it is also worth noting that once off the coastal shelf it gets very, very deep.

As an example, the search for the SS Central America (sunk 1850’s, found 1990’s?) was done off the East coast of the US. It was located about 8,000’ down. The number of man made craft that can carry humans to that depth can be counted (I think) on one hand.

Maybe this is in gross error but imo, in the open ocean submarines are less likely to hit another craft than airplanes are to have a mid-air collision.

I was onboard the USS Gurnard SSN-662, when it ran aground at test depth in May of 1989. We found an underwater 'mountain' as well. There are a couple of articles out there about it, but for the most part, it was all fairly hush-hush.
I honestly don't know the entire story about what all happened up front, as I was a nuke machinist mate and standing watch in the engine room when it happened.
Lots of scuttlebutt about the details, but the more people that told the story, the more confusing it came to be.
No public pictures are available of it, that I know of, but it looked pretty similar to the San Fran. Honestly though, the San Fran does look a bit worse than ours did.
Ed

Modern high accuracy inertial navigation systems don't use actual physical spinning gyroscopes.

One variant I am familiar with shines lasers through coils of fiber optic cable. If you rotate the system around the axis of the coil, the end point of the coil moves, making the path of the light longer or shorter. They can measure that change in fractions of a wavelength and measure the rotation with incredible accuracy. 10 years ago I worked with one of these units that cost more than most cars and could maintain an accurate three-axis heading to within something absurd like a hundredth of a degree.

quote:

Originally posted by Rey HRH:

quote:

Originally posted by Pipe Smoker:

Plus SONAR?

Underwater mountains aren't going to ping your sonar. Sonar is for passive listening. If you go active, might as well just shout, "Here I am!"

"Active" is also sonar, just a different type.

Of course you are correct that a sub trying to be sneaky wouldn't be using their super fancy fish finder.

quote:

Originally posted by Pipe Smoker:

quote:

Originally posted by rduckwor:
Charts, periodic GPS fix, and onboard inertial nav systems.

Clancy man, Clancy!!!

RMD

Plus SONAR?

Nope.

-Sonarman in the past-SSBN 656(G)

I always thought that they just waved a big white cane in front of the sub.

quote:

Originally posted by maladat:
Modern high accuracy inertial navigation systems don't use actual physical spinning gyroscopes.

One variant I am familiar with shines lasers through coils of fiber optic cable. If you rotate the system around the axis of the coil, the end point of the coil moves, making the path of the light longer or shorter. They can measure that change in fractions of a wavelength and measure the rotation with incredible accuracy. 10 years ago I worked with one of these units that cost more than most cars and could maintain an accurate heading to within something absurd like a hundredth of a degree per hour.

In my past life I tested "FOG's" on ground combat vehicles (fiber optic gyroscopes). While they were 'faster' than the standard mechanical gyros we used they were no where near as robust. High failure rate. The 'instant on' feature was nice but to this day mechanicals are still in use (on tanks anyway). This includes the gyros for the fire control system and the inertial navigation.

Back in the day we crawled the bottom.

CW

Look out the screen door?

quote:

Originally posted by ed32hall:
I was onboard the USS Gurnard SSN-662, when it ran aground at test depth in May of 1989. We found an underwater 'mountain' as well. There are a couple of articles out there about it, but for the most part, it was all fairly hush-hush.
I honestly don't know the entire story about what all happened up front, as I was a nuke machinist mate and standing watch in the engine room when it happened.
Lots of scuttlebutt about the details, but the more people that told the story, the more confusing it came to be.
No public pictures are available of it, that I know of, but it looked pretty similar to the San Fran. Honestly though, the San Fran does look a bit worse than ours did.
Ed

San Diego area wasn't it?

quote:

Originally posted by ZSMICHAEL:

quote:

I think over many decades of sub operations, immense amounts of time and resources have been spent mapping the oceans, and those charts are pretty darn good.

Naval Oceanographic. Located right here at the Stennis Space Center in south Mississippi. Mine warfare is out there as well. A lot of this stuff is top secret.

LINK: https://www.public.navy.mil/fl...ages/navo_home1.aspx

I think every time we go to Bilioxi or my cousin's place in Bay St. Louis we stop at Stennis and take the tour and go to Infinity.