From: "Gary Wiltshire" 

On Fri, 28 Jan 2005 22:25:33 -0500, Steve Ewing  wrote:

> On Fri, 28 Jan 2005 13:41:10 -0500, Gary Wiltshire  wrote:
>
>>
>> Depends on whether his charts were right or not.  Traveling at high
>> speed byinertial navigation without active sonar and with bad maps is
>> bad news.
>
> I read they took a sounding just before the grounding, like four minutes
> before, and got 6000 fathoms.  If they were already at high speed, that
> sounding would be highly questionable: the fathometer is "gated": you
> set it for the windo where you expect to get a return.  They could have
> gotten an echo/reverberation, rather than a true return.  Or, it was
> accurate and they just had Very Bad Luck.
>
> As for inertial navigation, it is very very accurate.  The charts were
> the problem, but that's second-guessing of the worst kind.
>

That's what I'm saying.  The charts are key, unless you want to constantly
go banging away and announcing where you are.

--
Gary Wiltshire

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