You will have to repeat the famous Philadelphia Experiment to find the cache.
Find the appropriate warship and remember the numbers in its name (you will have two different numbers ABC and DE, which mark the beginning and end of life of this warship).
The cache is located at coordinates N50 23.(385+(ABC*3-10)) E30 30.(646+(DE*3+7))
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You can validate your puzzle solution with certitude.
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