Oral, so many people here have shared their expertise, I've been feeling a bit remise not sharing mine in the rather arcane area known as submerged navigation. So, I think it's time to do a little DD since the press doesn't seem capable of doing it.
First of all, let's take the word of the press reports the accident happened about 350 miles south of Guam. Since Guam is located at 13.5N 144.7E, and since 1 degree of latitude equals 60 nm, that brings us to a grounding area of approximately 7.7N 144.7E. Breaking out an online map, that takes us into the Caroline Islands area. Plugging in Caroline Islands and charts, gives us this list.
81001,81002, 81016, 81019,81023, 81127, 81133, 81141, 81145,81148, 81151, 81155, 81166, 81187, 81209, 81237, 81249, 81251, 81288, 81303, 81327, 81329, 81338, 81345, 81411, 81427, 81435, 81453, 81488,
Now, let's take the list and plug the chart numbers into the Notice To Mariners corrections site and see whether a correction comes up that correlates to the accident site of about 7.7 degrees north, 144.7E. You see, it's not the age of the chart that matters, its whether it has been corrected with the latest Mariner information, which comes out weekly, and is required to be entered before use.
pollux.nss.nima.mil
81023 5Ed. 8/12/89 LAST NM 12/90 1/93
Add Depths
20 meters 8°03.4'N 147°45.9'E
31 meters 8°05.3'N 147°45.2'E
(14(1059)92 Taunton)
81023 5Ed. 8/12/89 LAST NM 41/95 10/96
Add Depth
30 meters 8°24.8'N 148°12.5'E
16 meters 8°03.4'N 148°33.8'E
(3(201)96 Taunton)
Notice only a few corrections stand out when we remember the grounding occurred at approximately 500 feet, which is about 152 meters.
Now the questions are, what chart did the crew use? Did they use the commercially available chart 81023 (which appears to have two corrections near the grounding site), or did they use a military bottom contour chart? Ahh, this is where things get a bit complicated, since submarines typically use bottom contour charts when transiting. Since bottom contour charts are corrected by Classified Notice To Mariners, are DD ends here.
Mike
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