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learning celestial navigation
The precision of the measurement you make with a sextant on a small sailboat is limited by the motion of the boat. I have found that, regardless of the sextant I use I can routinly get fixes within 2 miles (at sea)...
I have a C plath sextant that was a gift. They are very expensive to buy and I think its an inappropriate model for a small boat because it is so heavy. It might have been a fine choice for a freighter where the office could stand on a rock stable bridge and shoot the sun once and rely on the sight. I have found that, on a small boat, I need to repeat the sight several times to satisf myself that Im getting reasonable answers. You can either accept one of the sights of the set or plot them and pull an angle and time off the plot.
Because taking a few sights is a good idea I think the most appropriate of the metal sextants are the ones made by Frieberger (sp?) in Germany. They are slightly smaller that the C Plath and are aluminum so they are very light. They dont take up quite so much space either.
Plastic sextants work fine too. As with the metal ones always check the index error every time you use it.
I learned with the tables for air navigation but have switched to the tables that are built into the nautical almanac these days. I figure I would only use celestial as a fall back and dont want to carry extra books when the tables in the almanac will do the job (slightly more tedious).
Celestial is shrouded in mystery but it is really pretty simple. Once Nathanial Bowditch figured out a way to do the spherical trigonometry solutions using precomputed tables the sailor''s math skills only needed to be good enough to do addition and subtraction in degrees, minutes and decimal minutes. nowdays many calculators can do these calculations in decimal degrees and switch the values back to deg, and minutes for use with the tables.
This is a good skill to have. Its easy to learn. But dont spend so much on the sextant that you cant afford a spare GPS or two. When I sailed my boat from San Francisco to Hawaii a few years ago I did not see the sun until I was halfway to hawaii...But I always knew where I was within 86 feet, thanks to GPS.