Sight Reduction Tables

I have several books on celestial navigation and various references such as H.O. 229, 214, etc. Haven’t yet found out which is the most practical reference for an average yacht in open ocean. I have a GPS, of course, and wondered how frequently cruisers are using their sextants and if so, in what way and how often? It used to be a line of sight in the morning, a noon sight, and evening star sights. I suppose it’s now just a daily noon sight, if that.

We grew up using HO 249 for sight redutcion. However, the Air Reduction (I think that is HO229) is almost as accurate and is in one volume rather than three for 249. As to how often modern cruisers use their sextants, I can tell you from our own experience not often enough!

In the olden days our sextant was used on average of three times a day on all passages. But since we aquired our first Satellite Navigator in the mid- 1980s, this average has dropped to about once a year. Of course, using a sextant, and doing the sight reduction is not that difficult. The key is to get familiar with it and comfortable with the process, and then use it enough so that if a lightning strike or wave took out your electronics, you were close to navigational hazards, and it was blowing a gale, you could still figure out where you were. In that context, we keep our almanace and sight reduction tables in ZipLock bags–so just in case… Steve Dashew

Posted by Steve Dashew  (November 30, 1999)

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