I (Philip N. Ledoux) have rearranged the posts that were forwarded
to me for analysis. The source I cannot determine. I have to make a few
educated guesses. Apparently a Chinese sub, the Han, was in the same operating
area; reference is made to "the Han". In the reference "everybody
could detect it" could refer to the sea mount or to everyone else (USA)
being able to see the Han because it was actively pinging.
To me it was a bit humorous the discussions about fathometers,
but I include it because most readers are not familiar with how they work.
The fellow who comments the best has to have been a "forward
crew" with much experience (20 years from a post I omitted). The SSN
711 was cruising at 500 feet which he considered "deep", that
is because he is not allowed to tell. 200 to 300 feet deep was the limit
of the old diesel boats. Obviously 500 feet deep was piddling for a boat
with a 2 foot thick special flexible steel hull. From the picture, it is
obvious that the sea mount luckily was struck at an angle. From the damage,
I would estimate that had it been a "straight on" accident, we
would have had another "Arizona" monument 500 miles south of Guam.
I missed the news on the USS Salt Lake City; apparently it
too had an accident, and as is speculated, the damage to her is much less
than the 711, so the 711 will be taken out of service and probably the Salt
Lake City repaired. But those are high level decisions; us mere mortals
can only guess.
There must have been a crew of guardian angels aboard the
711!! The steel is buckled all the way back to the "living quarters".
The nose of the sub acted like the designed crumpling of auto front ends
in a crash, designed to take up the Impact. From the pictures, obviously
the "nose" is not made of 2 foot thick steel, and probably is
a similar design factor to absorb the shock of a disaster.
The sailor's comments are superb. I cannot do as well as he!
He pointed out that the stern portion was clipped in the pictures so nobody
would see those secrets. Ha, ha. I took the SSBN608 in the building. We
had one of the first non-cavitating screws installed on a sub. Gigantic
is an understatement. But it is the special shape of the blades that were
the secret. Cavitation is the condition where bubbles are created by a spinning,
loaded screw in water, and as the bubbles burst, it makes mucho noise which
is called "cavitation", imploding bubbles. By the time I left
the Navy, the US did not have the ability to cast a submarine screw. If
I remember correctly, ours was cast in Sweeden (1960), and shortly thereafter
the Russians had the design specs. So, who is fooling whom?
I have only rearranged the "posts" into a more logical
sequence for the reader. My hat is off to the original sub sailor who made
Philip N. Ledoux
- - - - - - - - - - -
subs use fathometers this is why the Han was using active sonar when it
was swimming around Guam The Han was pinging the sea floor for rising structures
to avoid a collision. Of course that meant everybody could detect it compared
to the LA.
The only problem is they [fathometers] look straight down,
not ahead. Try this experiment. Go outside and stand in a nice park. Look
straight down at your feet. Now, while looking straight down, run as fast
as you can randomly around the park. When you run headlong into a tree,
try to figure out why you did not see it in time to avoid it. BTW, US subs
do use fathometers all the time. The freqs and pulses are not detectable
to most sensors. I won't elaborate further (for obvious reasons).
As for the loss of the boat .. USS Salt Lake City was scheduled
for inactivation this summer. They will probably put the San Fran in her
place and overhaul the SLC.
Fathometers only see down...not out; among civilians, high
frequency sonar pinging everything is the only way to -- themigPost
You may be talking about things like side-scan sonars and
the like that give an image of the ocean floor. But those are towed devices
behind the ship and only see a path a few hundred yards wide. Most civilians
don't even care once they are out of port. Any obstructions that they worry
about are pretty well charted (why would a surface ship care about a mountain
400 feet below the surface?). Most freighters secure [turn off] fathometers
once they leave port. As for what the whale saw or did not see...I wonder
how you asked the whale that? I can imagine some scientists taking the sound
and power of a whales 'transmission' then doing some analysis and coming
up with a "its possible" scenario...but what the whale really
was doing is known only to the whale.
speed of the sub after the collision was reduced to ~5 knots, indicating
it wasn't a straight-on collision. I guess the picture shows this as well.
On the other hand, swiping another ship and swiping a mountain aren't really
the same thing either.....
But remarkably, the sub did not sink and still able to navigate,
in a limited sense, under its own power. It wouldn't be the case if it were
a Russian's or any other country's sub.
Consider me impressed
The damage is more extensive then I expected. It's hard to
believe the crew saved this boat considering they were fairly deep at the
- - -
Here's a question. Why do the US Navy release these pictures?
If it were Russia or China, these pictures would be highly classified for
fear of some small detail being noticed by the competition.
- - -
I'm sure the pics were checked before release. At some point
someone was going to take a photo and post it anyways. At least this way
the Navy can decide exactly what the photo shows. Notice the aft end is
cropped...no pic of the prop or rudder area. They also covered the actual
spherical array so the design and hydrophone placement could not be seen...along
with some other stuff that is up in the dome area.
During the cold War you could not even take pics of subs pierside.
Since then things have gotten less strict. They even released the patrol
report what one boat did as it 'escorted' a Soviet SSGN in the South China
Did a quick job here to point out some key things that I noticed
1. The area all the way forward covered by the blue tarp is
where the spherical array is located. It looks like the entire sphere is
off-center...hard to tell in this image. The GRP (fiberglass) type dome
is completely missing. In the upper section you can see part of a ring with
many holes and some bolts sticking through. That is the mounting ring for
the dome itself. A section of the ring is missing too.
About halfway down...just back of the tarp...you can see some
beige-white tiles attached to a metal bulkhead. That is the bulkhead that
seperates the dome area (which is always full of water) and the forward
most Main Ballast Tank.
2. The section just aft of the dome area. This is the area
that is painted that hideous puke-green color. That is Main Ballast Tank
1. That showed me right away this is not a PS image. Unless you have been
physically inside the MBTs of a US sub you would NEVER have thought of that
color of paint.
Anyways the entire port side of MBT1 is gone. The stbd half
probably could not hold air either. You can see the bulkhead that seperates
the MBTs into port and stbd. The green bulkhead with the green tiles on
it are the seperation beween MBT 1 and 2. You can tell most of MBT 2 has
lost integrity also. The outer skin is sort of there . . but badly wrinkled.
3. Note the bulge in the upper section of the hull (circled).
This is about where MBT 2 and MBT 3 have their bulkhead. Just shows the
amount of energy expended in the grounding.
4. A bit over halfway down you see 2 rectangular pieces of
metal pointed out. These are the torpedo tube shutter doors. Basically a
piece of metal that is connected to the tubes outer door so when the doors
are closed the hull is flush...no nasty openings that make noise.
5. I noted the temporary mounts that were welded to the hull.
This was so they could attach a cofferdam type device to the boat to seal
as much of the MBTs as they could after returning to port and to help her
stay afloat pierside.
That's a quick down and dirty. If you have any follow up questions
feel free to ask. I'll answer to the extent I am able/allowed.
- - -
Replying to: How do US subs blow their ballast tanks? --
The holes you see in the casings of boats like the Song, Kilo,
Victor3, etc are there to vent the outer casing. Those boats are double
hull construction. They have an inner pressure hull. This is where all the
people and equipment are at. The outer hull is only a casing to cover pipes,
airflasks, cables, and other stuff. Since this area is not designed to hold
pressure it has alot of holes in it to allow the air to vent out and the
water to flow in when the boat submerges, and for the water to quickly drain
away when the boat surfaces. In that construction what you are looking at
is not the pressure hull of the boat, but only an outer shell for streamlining.
US subs are single hull construction. That means that except for the Main
Ballast Tank at the very forward and aft ends, you are looking directly
at the pressure hull. This has the advantage of being quieter since you
don't have to deal with all the turbulant flow from the vent holes), faster
for less power output (since your hull is more streamlined), but also probably
more expensive since the craftsmanship of the hull has to be that much more
precise. As for the way US subs blow their MBTs:
The first method is called the Emergency Blow System (EMBT).
Inside the ballast tanks are where the high pressure air flasks are located
(in the photo a lot of them are gone, but I did see the top of one in the
wreckage). These air flasks are arranged and piped together in groups called
"banks". 1 bank is used to supply the HP air that the ship uses
for services like Hydraulic presurization, Emergency Breathing, pneumatic
The other banks (more than 1) store HP Air for the EMBT system.
When activated, it dumps from the flasks strait into the Ballast Tanks which
forces the water out from the vent holes in the bottom (they are designed
specifically to not make the 'coke bottle' noise when the boat moves). This
sudden increase in buoyancy makes the boat surface immediately. Its a fun
The normal way to surface is to come to shallow depth and
raise the snorkle mast (a big pipe to let fresh air in the boat to either
replace the stale air or to provide air to operate the Diesel Generator).
You then broach the boat (basically use the engines to force the boat onto
the surface .. once broached a boat tends to wallow their like a beached
whale). You then start an air blower (basically a big air-pump) to suck
air from the snorkle mast and push it into the MBTs (since your already
at the surface you need less than 20 psi to force the water out). After
a few minutes the MBTs are full of air and the boat is stable on the surface.
In the San Frans case they were running the blower constantly because they
could not afford to lose any more bouyancy...and now we see why.
The pic is a 688 doing an Emergency Blow. Imagine the power
needed to get 7800 tons half way out of the water. (This picture not included.)
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