[R-390] OT: Submarine navigation

[Raymond Cote]

Remember that star sightings only have position, not heading. Once position is determined the sub then uses whatever heading it can determine from past fixes as to what direction it is going. You cannot get heading from a star or other fix. Only by deducing your track from past fixes can you dateline your heading. A gyro sim pass using speed thru water can give you an idea as to your track thru the water. 

> On Sep 9, 2014, at 8:00, Roger Gibboni <rgibboni at lmdulye.com> wrote:
> 
> Directional gyro that was reset with star sightings when they could surface.  The longer between star or sun shots the more th DG drifted.  Same as in an airplane.  Enen today the only true north pointing instrument in an airplane is the wet compass.  
> 
> Roger Gibboni
> 845-987-7744
> 
>> On Sep 9, 2014, at 8:40, Blair Batty <blairbatty at gmail.com> wrote:
>> 
>> Sorry for the off topic, but I know there are lots of ex-military types
>> here; I don't know where else to ask.
>> 
>> How did a submarine navigate during WW2? Did a compass work underwater
>> inside an iron tube? Did they just look thru the periscope to see where
>> they were going? Dead reckoning? Or were they mostly a surface vessel.
>> 
>> I suppose today they have all sorts of magic, electronic gps devices, so
>> they can travel for months without every surfacing. But what was available,
>> say in the 60's-70's?
>> 
>> Sincerely
>> /b
>> 
>> Questions inspired by a cold war submarine movie last night...
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