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How are your navigation skills?


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Thanks for the kind words Kevin.

BP, to your point, I recall an approach to the Cook Strait area from the Tasman in the days before Sat Nav and GPS.  The weather had closed in and the wind was fresh from the south west.  I had no sextant sight for 24 hours and we had not seen land.  We were still north of Cape Egmont.

Over the space of about 30 minutes there was a very noticeable change in the waves and the motion of the boat.  One of the crew even had a little panic because he had not experienced this before and convinced himself we were about to run ashore.  Our DR coincided with the rapid reduction in ocean depth as shown on the chart, but we only had a simple depth sounder on board which was useless at those depths.  This was still the days of RDF and Cape Egmont broadcast a good signal.  I had a B&G Homer RDF and headphones and got a good null off Cape Egmont.  The position line from the RDF passed close enough to the DR position to give me comfort that we were crossing the shelf and experiencing the sea change from the rapid change in depth.  This was at about the spot shown on my crudely drawn attachment.  RDF signals are more subject to a polarization error at night (and it was night) so I was a tad concerned, but the ducks seemed to be in a row.  

Now we just look at the chart plotter - but the old tricks still work.

 

778396383_CapeEgmont.thumb.jpg.d6a00a99e1c5bc0377b6ae85b078780c.jpg

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Slocum used a sextant and tables. He even claimed to have used the lunar distance method to determine longitude though this may have been more of a tall story.

Slocum took regular meridian passage sights but may have relied on DR more than he let on for longitude.

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