On 2/14/10 12:34 AM, "Poul-Henning Kamp" <[email protected]> wrote:
> In message <[email protected]>, Neville Michie
> wri
> tes:
>
>> We had a system of secondary radar called DME [...]
>
> DME is still going strong, and is the main GPS-Backup over Europe
> for air-traffic.
>
>> I do not know how shipping located themselves.
>
> Possibly Omega...
>
Or Transit, or celestial nav for open seas, pilotage (perhaps with radar
assist) for coastal waters. After all folks did successfully navigate ships
long before electronics was common place (most of the time, anyway<grin>)
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