What is your backup GPS solution?
- Thread starter Jackdaw
- Start date
Actually, where we sail, I feel less comfortable with a non-functioning depth sounder than I do with navigation not on. We basically can tell by sight where we are anyway. I generally know by sight where we are in the bay and can relate it to probable depth without really looking at the chart. But if I don't have that visual aid that tells me I'm in 9' of water (comfortable) vs. 5' of water (uncomfortable) … I'd be sweating for sure!
That obviously wasn’t my point. Of course everybody should have a good set of charts. My questions regarding Backup of a fixed GPS.
The GeoNav 4C WAS A bit of a unicorn, a technology demonstrator created to show the world that a handheld platinum chart capable device could be built. It was very expensive, and rather short-lived.
GPS failure? Well sometimes I forget to turn it on when I leave until I’m halfway down the channel. In order to get to open ocean I sail south down a channel 20 miles long and about 5 miles wide with steep mountains on each side. Then I turn left or right until I duck into another bay that is 10-20 miles long... when I return, I just do the reverse.
Anyway, I have downloaded maps on a few devices that have an internal GPS as well as paper maps.
Anyway, I have downloaded maps on a few devices that have an internal GPS as well as paper maps.
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I remember a few years back, sailing on the Chesapeake Bay, near the mouth of the Potomac ,when our chart plotter lost GPS signal so we turned on our trusted Garmin handheld and there was no signal to be found. Out came the paper charts; and our compass and the depth sounder all of a sudden gained increased relevance. After maybe 15-30 minutes the GPS units regained a signal. That evening we were talking to one of the locals and he said it had been happening, that apparently the military was running some tests by interrupting the signal for short periods of time but without notice. I do not care how fancy a GPS unit might be if the signal is jammed it is not going to be of any good. Sailors that may not be familiar with setting a rhumb line on a paper chart it would be highly advisable for them to learn and practice. Was aboard a Coast Guard cutter once and noticed that even with all the electronics aboard a sailor was tasked with manually maintaining a rhumb line and plotting estimated position on a paper chart every hour on the hour. Was told that it was done to corroborate what the electronics were telling and to have positional awareness in case the electronics failed. I may not use manual navigation these days but I'm constantly aware of my headings and match depth sounders readings to those given for the position on the chart plotter.
Has anyone taken the ASA 114 Celestial Navigation course? I've been considering it because I think it would be really interesting even though it's probably not necessary with the litany of other tools available these days.
Took the ASA celestial course through Maryland Sailing (Capt. Tom Tursi) and was very pleased. I never expect to use it "in anger" but I do practice every so often, and can actually take sights. Really proficient celestial (daily practice, no reduction errors, etc.) will get you within a couple miles, if you're lucky, and takes the better part of an hour to get that fix. Completely worthless for any piloting if you need to know where you are to avoid rocks in the current hour. It's highly dependent on ded reckoning, so you kinda have to know where you are before you more precisely know where you are.
Well, ain't this a hoot?
I went to take a picture of my Garmin GPS 45, that I purchased somewhere in the early eighties, which was my primary navigation tool in its day and my back-up since I've been on boats with installed chartplotters.
Damn thing won't turn on! Changed batteries and did all I can think of, but I think it's dead.
So, thank you Jackdaw and I'm going to look at the GeoNav 4C right now!
Oh no, I'm not! Apparently, there isn't one for sale anywhere on this planet.
Oh well, gotta go look @ what Garmin has to offer.
I went to take a picture of my Garmin GPS 45, that I purchased somewhere in the early eighties, which was my primary navigation tool in its day and my back-up since I've been on boats with installed chartplotters.
Damn thing won't turn on! Changed batteries and did all I can think of, but I think it's dead.
So, thank you Jackdaw and I'm going to look at the GeoNav 4C right now!
Oh no, I'm not! Apparently, there isn't one for sale anywhere on this planet.
Oh well, gotta go look @ what Garmin has to offer.
Celestial navigation is not a good back up for GPS. To be halfway proficient, one must use it every day, several times a day. It is not something one can just pick up and do at the drop of a hat, even if one is quite familiar with the method. Getting a proper site on a moving small boat at sea is one of the most difficult things one can do on a boat. And in order to actually have a fairly accurate position, one must have three fixes (reduced sites which give you LOP's) as far apart as possible, usually around three hours.
I'm not saying don't learn, just saying it isn't a back-up for GPS unless you are a week or more away from the nearest rock. I wouldn't waste the money on a class. The Kindergarten of Celestial Navigation by Sellars is the best book ever written on this and has worksheets that are reusable.
Just as info, when I circumnavigated, GPS had not been invented and celestial was all we had.
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I picked up this old N5G INS a few years ago that was on a B-52 bomber. It will probably kill my batteries in fifteen minutes, but screw GPS. Just have to figure out where to mount it.
If you're talking about finding a position in the ocean out of sight of land, then yes. However, triangulation on a chart with known landmarks is about as accurate as you will ever need. Dead reckoning will get you most places within a hundred mile track. I've come within 10 feet of the can I was sailing for in a fog that wouldn't let you see twenty feet, after sailing (rowing with 14 other rowers on a pulling boat) 4 miles up a channel without seeing the land.
Backup for GPS? Attention and planning. If navigating in the open ocean, having plotted out the course and planning the course corrections, losing a GPS should only be an inconvenience. In emergencies, an extended storm that throws you off track, a second gps is great, celestial navigation skills can't be lost, run out off power or broken. However, if you're sailing near shores and rocks and other obstacles, charts, clock and compass are irreplaceable. Also a smart phone. Nothing is better than thinking ahead, planning and knowing/scouting the area you will be sailing is important.
Keep a watch and check your bottom depth of in question.
I've rented small boats with gps to get from point A to point B, but they give a turn by turn instruction and if they blink out, there is no record, no plan, not even a general, "go that direction". I like sailing by the compass, not by the computer screen.
-Will (Dragonfly)