NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Uss Lamoure County
From: Stacy Hanna
Date: 2004 Jan 25, 18:27 -0500
From: Stacy Hanna
Date: 2004 Jan 25, 18:27 -0500
While I agree that it was not a GPS error, it was an error caused by relying only on GPS. If the ship had been using radar navigation (as it was required to do by navy instructions in a low visibility situation that close to land) they would have noticed the discrepancy with GPS and hopefully would have stopped the ship (or turned back to deeper water) until they could determine the cause of the error. As I stated in an earlier message, a good navigator uses every available means to determine his position and doesn't place full confidence in ANY single system. (A sextant, unless used for horizontal angles(not possible in a low vis situation, the same as any other visual piloting), would also have been an inappropriate way of fixing the ships position that close to shore but soundings and radar ranges could have probably prevented the loss of the ship) -----Original Message----- From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM] On Behalf Of Jared Sherman Sent: Sunday, January 25, 2004 17:26 To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: USS LAMOURE COUNTY Joel-GPS only on Chilean charts that used a local datum without taking into > account the datum shift.> That's the bottom line. This was not a GPS error, this was a navigational DATUM error ("pilot error" as the FAA calls it) caused by using *any* means of determining position, and then incorrectly applying it to local charting. If they had used a sextant, they would have still run aground because they still would have been using the wrong charts (wrong chart datum) to go with their position. Apparently the GPS reliably did what it was supposed to do, as it was supposed to do. And the navigator did the unforgiveable, entering shoal waters after incorrectly charting his position. By the way..."USS" would be a US merchant steam ship, as I understand it. "USN" would be a US Naval vessel. A similar small mistake is all it takes to get the datum wrong, regardless of the method for obtaining position fixes. Well, unless you're using rods and chains stretched from the beach. Then we can still miscount the chains.