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Re-navigation
Meanwhile back on shore, Dave Jourdan was using Nauticos' RENAV
system to re-construct the tracks of the vessels involved and develop
a more accurate position based on the original logs of the surviving
ships. The location reported by the Navy was based on real-time
navigation of the era, using celestial fixes and rough dead-reckoning.
The accuracy of their estimates was compromised by many factors,
including bad weather, winds and currents, frequent maneuvers during
flight operations, and zig-zagging to avoid enemy detection. These
factors kept the crews from obtaining good star fixes and accurately
updating positions. Of course, the crews were less concerned about
their precise location (in the mid-Atlantic) than they were concerned
about the relative location of the enemy. Finally, since the attacks
occurred so far away from the ships, the geographic location uncertainty
of aircraft after several hours of flight time (in high winds at
night) added to the errors in reported position.
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Survey plan, April and May of 1995 |
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Reconstructed routes of the USS Bogue task force and U-530 during
and after the attack
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As
the searchers neared completion of their search in the primary sector,
the staff at Nauticos intensified their RENAV efforts. Paul's research
had been made available just before the ship's departure. A rather
unique approach was used involving software originally developed to
analyze and reconstruct tracks from modern nuclear submarines. This
software helped analysts at Meridian generate dead-reckoning tracks
of the World War II vessels over several day periods. These data were
fitted to position estimates using a Kalman filter, estimating bias,
scale, rotation, and other errors in the tracks. This allowed many
fix estimates from different vessels over a long time period to be
integrated statistically, refining the positioning at any particular
time.
Many available observations of the attack and
wreckage were compiled, yielding a position estimate for the site
of the sinking. This was in turn adjusted for current drift as the
wreck made its more than three-mile journey to the bottom of the ocean.
The result of this analysis showed the location of the I-52 to be
over 10 miles from the Navy's originally-reported coordinates. Plots
and supporting information were sent to the ship via electronic mail
over satellite communications. After considering the new data, along
with supporting results from manual analysis done on board, the Yuzhmorgeologiya
rushed to search the new area before dwindling fuel and supplies forced
an end to the cruise. |
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