SUBMARINES: Why the USS San Francisco Ran Aground
January 12, 2005: The American nuclear submarine USS San Francisco hit an
uncharted seamount on January 7th, killing one sailor and injuring 23
others. Facts about the incident were slow to emerge. It appears that the
sub was traveling on a course it was ordered to follow, at a depth of 500
feet and a speed of about 56 kilometers an hour. This was the first time
the navy had given the speed of a Los Angeles class sub as anything but
"25+ knots" (45 kilometers an hour.) It has long been believed that these
subs could make more than 55 kilometers an hour.
The visible damage to the sub indicated that the sonar dome at the front
of the sub was partially collapsed, and, according to information released
by the navy, some of the forward ballast tanks were damaged. The pressure
hull was not compromised. The submarine immediately surfaced after the
collision, which was apparently a glancing one. The crew had some trouble
getting to the surface, because of the damaged forward ballast tanks
(which hold water, that is rapidly pumped out, and replaced with air, to
give the sub buoyancy and bring it to the surface.) The impact, of course,
caught everyone unawares, which is why there were so many injuries. The
sailor who died, had been thrown forward, hitting his head on a pipe. He
died of that injury two days later.
The captain usually losses his command after accidents like this, although
in this case, that might not happen. If the captain was following all
procedures correctly, and there was no way the seamount could be detected,
the incident might not destroy his career. There are many uncharted
underwater features, especially 500 feet underwater. The technology does
not yet exist to economically chart all of the ocean bottoms to that, and
greater, depth. Most waters are charted sufficiently to protect surface
ships. But there are only about two hundred subs that normally operate at
the depth this accident took place. There may be a call for the navy to
change its procedures, and have the sub use more active sonar devices when
traveling in certain waters. But this will generate protests, because
active sonar disturbs the fish. There are also technical issues regarding
how effective such sonar would be in avoiding all types of underwater
collisions. Moreover, in wartime, you avoid using sonar as a navigation
aid, as it gives away your position. Actually, traveling at high speed
gives away your position, because of the noise generated by the propulsion
system and water rushing over the sub. In wartime, the sub might have been
moving at 10-20 kilometers an hour, which would have caused less damage
and fewer injuries.
If the Navy adheres to maritime tradition, that calls for the naming of
previously unknown underwater features after the vessel that "discovered'
them, even if by running into them, the uncharted seamount will now be
known as the "San Francisco seamount".
Accidents like this are rare, but there will probably be a review of the
charts, of underwater geography, that are used by American subs. This
review process is standard whenever there is a major underwater earthquake
or volcano eruption. For example, the December 26, 2004 earthquake off
Aceh is known to have seriously rearranged the ocean bottom in that area,
and efforts are already underway to update charts. But now an effort will
be made to try and determine where there may be other potential "San
Francisco seamounts".
Topic: Things that go bump in the night, or how the USS San Francisco ran aground! (Read 853 times)