# If the GPS Fails I'm Riding the Isobars Home

**URL:** <https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962>\
**Category:** Scuttlebutt\
**Created:** [July 1, 2019, 11:14am UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962 "2019-07-01T11:14:33Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Kennebec\_Captain](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.gcaptain.com/kennebec_captain/32/13_2.png) [@Kennebec\_Captain](https://forum.gcaptain.com/u/Kennebec_Captain)\
**Post date:** [July 1, 2019, 11:14am UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962/1 "2019-07-01T11:14:33Z")

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Working the problem the other way. Instead of plotting the position on the wx chart and looking at the weather just do the reverse. Look at the weather and plot your position. Navigate using the wind speed/direction and air pressure.

It would be like using knowing your altitude and a topo map to find your way in the woods. You’d need both current weather maps and the forecast. Should be good for 96 hours of navigation.

 ![image](https://us1.discourse-cdn.com/flex016/uploads/gcaptain_maritime_forum/original/2X/e/e31cbd96a252a698022cc271e41605b2167fb76c.png)

Assuming of course the navigator is the “good seaman” of legend.

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**Author:** ![Klaveness](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.gcaptain.com/klaveness/32/7001_2.png) [@Klaveness](https://forum.gcaptain.com/u/Klaveness)\
**Post date:** [July 1, 2019, 11:18am UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962/2 "2019-07-01T11:18:08Z")

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Now just add a sounding, and you’ve got yourself an Observed Position.

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**Author:** ![Kennebec\_Captain](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.gcaptain.com/kennebec_captain/32/13_2.png) [@Kennebec\_Captain](https://forum.gcaptain.com/u/Kennebec_Captain)\
**Post date:** [July 1, 2019, 11:40am UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962/3 "2019-07-01T11:40:37Z")

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The other day I was thinking about the phrase “using all available means”.

The phrase is only pertinent in cases where the reliability of the information is low enough that more data is needed to obtain an EP of sufficient total reliability.

It applies less today in some case for example pilot waters where there is more than enough reliable information, to continue to seek info would be at the cost of attention best used elsewhere.

In low information situations it’s a matter of putting the appropriate weight on data of varying characteristics.

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**Author:** ![powerabout](https://avatars.discourse-cdn.com/v4/letter/p/43a26b/32.png) [@powerabout](https://forum.gcaptain.com/u/powerabout)\
**Post date:** [July 1, 2019, 1:25pm UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962/4 "2019-07-01T13:25:30Z")

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the you guys will just ask Google…

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**Author:** ![valvanuz](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.gcaptain.com/valvanuz/32/675_2.png) [@valvanuz](https://forum.gcaptain.com/u/valvanuz)\
**Post date:** [July 2, 2019, 6:41am UTC](https://forum.gcaptain.com/t/if-the-gps-fails-im-riding-the-isobars-home/51962/5 "2019-07-02T06:41:37Z")

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As long as you stay 100 milles from shore…