Celestial Navigation? Forget it!

[sailingdog]

Every form of navigation has its shortcomings and weaknesses. Not knowing as many forms of navigation as you can is fairly stupid IMHO. The more choices and ways that you have to check where you are, the more likely you are to be where you think you are. Having redundancy is never a bad thing.

[camaraderie]

[quote=Surfesq]Camaradie:
In my opinion, this is the problem with GPS. It makes non-sailors think they know everything they need to know about navigation because a computer screen gives them information. Yet so many lack the most basic understanding of the principles of navigation.[/quote]

Surfesque... Absolutely. I was really just addressing the GPS vs. Sextant thing, not navigation skills. Again...I think those who have taken the time to learn Celestial should be proud of the skill. Nevertheless, I feel Celestial is obsolete now. I was proud of my DOS skills which were hard won...but then Windows came along and now they are obsolete. Still, I value what I learned and the step by step understanding of computing problem solving they gave me. I think this is similar to the Celestial Nav learning of others.
You are right, too many cruise without any navigational knowledge other than the little pointy thing on the screen. But...with good, developed coastal navigation skills and lots of little GPS devices on board, I feel quite a bit safer than I would relying on sun shots as my backup.

[Surfesq]

Yes, you make a great point. I know Celestial Navigation and have started teaching my 5 year old. Not because I would rely upon it anymore but because it is a very cool thing to know. I think if you are going to have sailing street cred you almost have to know it!
But the idea that the government will reclassify GPS is just silly. On another thread, I laid out what the governmet actually uses for its missles and GPS is just one small part.

[Headingsouth]

Artwerk, I'm sure you still have a butter churn and a hand lawn mower, but that doesn't mean you'll ever have to use them. Wasn't debating that the knowledge is good, and yes, I do get frustrated when a cashier can't give me the right change because the cash register is down. Still, I don't think I've used a jack in 20 years.....

[dave6330]

This has been a fascinating thread to read, both in terms of the absolute polarity between the points of veiw and the intensity of the opinions offered.

As a newbie, I have only sailed during the daytime (easy to do in the Alaskan Summer) and have always stayed within sight of land. I have charts that I follow, keeping track of my position by visual sightings. Dead reconning is something I have to practice on, just in case of the rare fog.

Our boat had a defunct LORAN when we bought her and we replaced it with a Garmin chartplotter (set up at the NAV station only). I use it mainly for a backup for the paper charts and to track where I've been. I have a small (cheep) handheld that I keep with an extra set of batteries in a pelican case, just in case, and I've set up some waypoints on it that I might find useful in an emergency (like the entrance to sheltered coves and the small boat harbor).

Someday, I'd like to learn CN out of a sense of personal development but I think the likelyhood of my having to rely on it is remote. I still want to try my hand at it and, God willing, if I ever get to make a crossing, I'll have it in my "tool kit" as a backup.

[CellNav]

GPS is a great system and very easy to use, but not fool-proof. There are places on the earth where geometry and signal strength are poor. Also space weather comes into play from time to time. Solar storms can wreak havoc on reception. For coastal navigation this isn't a big problem, but on the open seas it could be your only hope. Keeping at least a basic level of proficiency in celestial nav makes us better sailors and brings us satifaction. There's a reason were sailing and not racing jet-boats. We're keeping a way of life alive. Cell is an ancient art which only a dwindeling few still practice. I hope I never have to bet my life on my cell shots, but it does give me an extra measure of confidence when land gets very low on the horizon.

[sailingdog]

I'd really like to know where the geometry on earth is poor...

Solar storms are a big problem, as the GPS satellites only use about 50W of power to transmit. So is rain fade.... in really heavy weather, the GPS often loses signal for a short time. Although CN doesn't help in the case of rain fade, the other traditional navigation skills, like dead reckoning are needed at those times.

The funniest story I've read on celestial navigation is where a guy kept a GPS on his boat to use as a time-piece for the CN observations. Didn't really know how to use the GPS for navigation, but like the fact that it was very accurate as a clock, getting the time updates from atomic clocks aboard the GPS satellites.

[camaraderie]

[quote=sailingdog]Solar storms are a big problem, as the GPS satellites only use about 50W of power to transmit. So is rain fade.... in really heavy weather, the GPS often loses signal for a short time. Although CN doesn't help in the case of rain fade, the other traditional navigation skills, like dead reckoning are needed at those times.
quote]

And how do you take a sun shot during rain and heavy weather? Gps can lose signal for short times (though it has never yet happened to me in the 10+ years I've owned one! I have seen the signal "degraded" to about 20 times the accuracy of the best celestial shot!)... but you REGULARLY CAN have cloud cover day and night for days on end. Just how do traditional skills beat GPS on this issue?? I fail to see it! The same weather that MIGHT make it difficult to get a gps fix for a few minutes makes it IMPOSSIBLE to get a sun/star fix!

P.S. I love a good argument!

[sailingdog]

Originally Posted by camaraderie

And how do you take a sun shot during rain and heavy weather? Gps can lose signal for short times (though it has never yet happened to me in the 10+ years I've owned one! I have seen the signal "degraded" to about 20 times the accuracy of the best celestial shot!)... but you REGULARLY CAN have cloud cover day and night for days on end. Just how do traditional skills beat GPS on this issue?? I fail to see it! The same weather that MIGHT make it difficult to get a gps fix for a few minutes makes it IMPOSSIBLE to get a sun/star fix!

P.S. I love a good argument!

You don't. But you don't often really need to take one, especially f you're good at dead reckoning. If you're in the middle of a bluewater passage, then you're generally far enough from land that being off a bit doesn't really matter all that much... being 300 miles or 320 miles from land is not that big a deal. If you're close to land, traditional navigation and position fixes take care of that.

What you seem to fail to realize is that in many areas, the GPS fix is not very good, although it is very accurate as to where you are...it does nothing to tell you where you are in relation to what is around you. Many parts of the world have charts that are based on relatively ancient and fairly inaccurate nautical surveys. It doesn't matter how precise a GPS is, if the chart it is using is not correct or accurate.

For example, there are places in the Caribbean and South Pacific that will indicate that a boat is about to hit solid land, when in reality, the land is a half-mile or so off. The GPS is really a good approximation of your boat's position on a cartographer's interpretation of the real world, and may have little to do with where you are in reality.

The Mark 1 eyeball is much better and more reliable in these areas, since all the position information on an inaccurate chart is worthless...and many charts, are inaccurate to some degree. The less important commercially and militarily the area is, the more inaccurate the chart is likely to be.

[Tea-Rex]

maybe it is because english isn't my first language, but there's something i don't understand in your post.

why is it a problem when GPS is off half a mile, yet no problem at all when your celestial fix is off severall miles?
or why is signal loss for an hour or so a problem when you only need a fix every so often to sail savely to your destination with "traditional methods"?