Rodney Myrvaagnes wrote:

Actually, the GPS was not in use. It was just that nobody thought to
check if it was for 600 nm. Reconnecting the antenna would have solved
the problem, as would have several of the other things nobody bothered
to check.

They were "integrated-bridge-system centric." A significant
difference.

It's a point, but let me explain why I'd put the main blame to "GPS
centric".
When they left Bermuda they had three systems available for Navigation.
GPS, Loran, Celestial. Since the GPS wasn't working, the integrated
system reverted to DR (and obviously did a damn fine job, considering)
and followed the prescribed track (here, I'm not sure of a doppler input).
Other than a cursory check of the Loran and, it would appear, no system
check of the GPS (no celestial was used) the "system" was allowed to
proceed.... i.e., the Loran positions were not all that far from the
assumed GPS.
Now, on the approach to the Nantucket-Boston Safety Fairway, things
should have changed. Your Loran is pretty good, You come on soundings,
You have Radar Targets, You can make allowances to use visual checks,
You know there are strong, contrary currents in the area, but none of
these tools were seriously used and none of the dangers were considered.
Why? Because the navigators were GPS centric, believing their Nav
Plotter was getting the correct information from the GPS and not using
other "systems" to confirm that this information was correct.
The fault here was not GPS nor the integrated system. The fault here was
navigators relying solely on one system to be correct all the time.
If you are going to be navigating, you want back-ups to your back-ups.
Sure, You can carry 20 hand helds and 4 cases of batteries, but what
happens when the Chit, negatively hits the fan and all you know is GPS?
What happens when the system fails and you are not aware of it and you
go merrily on your way, believing it's working?
No, they were GPS Centric. They believed everything was fine, when a
system check would have said otherwise. They didn't use back-ups/double
checks, they believed the GPS would always work so consequently the
integrated nav system must be correct and never needed checking on, for
whatever reason.

Basically what I'm saying is go back to the first basic error. The GPS
wasn't working, no one checked to see if it was... they were "centric"
in that they assumed it would be, when in truth, for any number of
reasons it may not be and the prudent navigator realizes this and
checks, especially in areas such as the Nantucket-Boston Safety Fairway.

otn