Navigation poll

[Tellie]

GPS??
Sextant??

I went sailing to get lost in the first place.

[Kanani]

I made my first open ocean passage in Jan '84 (SoCal to Hawaii). Sat-nav had just become available to the public. I paid $1200 for it but I also realized that I'd better have a back-up. I purchased one of those plastic sextants for about $60.

On the way to Hawaii I found out that If the Sat-Nav was farther than 60 miles from where it thought it was, it could not find itself. The only way to rectify that problem was to put in a position within 60 miles of where we were.

I thought that I would save power by only turning on the Sat-nav twice a day to get a fix. That's when I found out that I shouldn't have done that. The real problem was, I ran down-wind in a storm for about 18 hours and had no idea where I was when it was over.

Well, I opened the sextant box and broke out my book on celestial navigation, while on a SW course (couldn't go too far wrong). After struggling with all of the formulas for a few days, I decided to check the instructions in the Sextant box. I found that it had an easy way to take Sun shots and the next day I got a fairly accurate fix (about 10 miles off). I plugged in that fix and I was back on-line again.

The moral to this story.......don't go to sea without a sextant and the instructions to use it.

[GordMay]

Originally Posted by rebel heart

… Sextant people, to me, 9 times out of 10, generally represent. …

Thanks.

I’m imagining trying to define “sextant people” in a PC manner, and enjoying a good chuckle ...

[imagine2frolic]

I have a sextant with all intentions of learning, but in class it just kept going over my head. When I would raise my hand the instructor would say.....DON'T WORRY WE WILL GET TO THAT. I sailed out of the bay before she had a chance to get to it......

I began to run a DR as soon as I left S.F., and all the way to Mexico I was always close to my GPS fix. I had wind, and current with me so there was no drift. It was a good lesson though, and I continued to practice it.

Years later while in the Fl. Keys with my wife. We were moving from one side of the island to the other. Weather was coming, and we didn't want to be on a lee shore anchored. While passing between the 2 islands the GPS quit recieving. The alarm went off, and so did my wife. She thought the sky was falling. It began to rain, and vision was limited, and at times just past the bow was all that could be seen.

We could have cut a corner short, but that brings us close to thin water. I did a little time, and speed to get distance. Added a little more to be sure I was clear, and then turned the boat. I put a little more math to our problem, and finally said we will anchor here. The depth was correct for my calculations. Dropped the hook, and settled in for dinner. Before dinner was served the sky cleared, and the GPS got it's fix. We were almost sitting on top of our intended spot for anchoring. It took us a little over an hour with a 120* turn thrown in to drop the hook.

Over dinner we had a small discussion about DS&T. I should have kept it a secret, because up until I explained DS&T she thought I was a genius. The plotter gave us our last known position, and time. What is that 3rd, or 4th grade math?...LOLOLOLOLOLOL

[Nightwatch]

I think I know where the sextant is, but I do not have any instructions left. I think I can do sun lines, Surely there is some software that will teach those of us that have forgot how. If I am going to be out after dark, we always keep a log on GPS positions. I like to plot a DR on my old paper charts. I guess I should dig out the sextant and see if I can still find a star and bring it to the horizon. We are getting the boat ready to go out there, need to get me ready again also.

[hellosailor]

Wm. Buckley's video of basic celestial navigation will show you how to use a sextant very celearly, and includes a very small set of practice tables for some exercises. Mary Blewett's little book will give you a little more information, also in a digestible "just do this" format. But for a real step-by=step background that will teach you why you are doing things, and what they mean in context on a circular planet (ok, ellipsoidal planet), try Mixter's Primer of Navigation. Literally a "primer" that takes you from the basics up, in a very simple clear writing.

There are a number of web sites that also explain why/what to do, but for anyone who is rusty or gets fuzzy with numbers, the best thing you can do is use sight reduction SOFTWARE that is free (for the PC) or inexpensive, for the Palm and other PDAs. A cheap old PDA for $35 and another $20 for the software to run on it, and you can forget about basic math errors. Or at least run a check on them, while you're also doing manual reductions. Math needn't be a boogeyman any more.