For back up I always have my GPS to double check my charts plus compass (and sometimes depth sounder). I'm such a contrarian.
What is your backup GPS solution?
- Thread starter Jackdaw
- Start date
Nothing is 100%. But if your main unit has a 5% chance of failure and your backup has a 50% chance of failure, then you've increased your chances of success from 95% with your main unit to 97.5% with a half-a$$ed backup aboard.
I have only had the civilian GPS sat network go down on me one time. It was up near Baltimore during the the Kuwait war (1990). My handheld Garmin 88 lost it’s signal. A crew member simultaneously pointed to the sky where the new B-1 bomber was coming overhead, returning from the ME. Signal came back up moments later as the plane cleared the area. I assume it was related jamming.
The early GPS devices could establish a pretty accurate location fix with just 4 or so satellites, I assume that even if some malign actor took down a few of our now very large sat array you could still get a fix that was more accurate than dead reckoning or even a sextant. Fixes would be slow, but the technology seems pretty flexible. Especially under a full-dome horizon (at sea).
The early GPS devices could establish a pretty accurate location fix with just 4 or so satellites, I assume that even if some malign actor took down a few of our now very large sat array you could still get a fix that was more accurate than dead reckoning or even a sextant. Fixes would be slow, but the technology seems pretty flexible. Especially under a full-dome horizon (at sea).
Our redundancy of GPS devices has grown quickly. These days we have at least 4 separate GPS receivers onboard just around home. If we're off for a few weeks in NE, we'll have at least 6 or 8 depending upon who's with us(you can have guests download a free nav program for their own fun).
The ship mounted CP used to be the primary but now it's hard to say which is the back up, today. I like an Ipad for my main navigation, piloting and route planning but phones are becoming more useful for navigation.
I like separate software for it's unique functions and settings and even opinions. I can set different reference bearings on screens that help me pilot.
Portability of these devices is important to me because weather and sailing conditions determine where I'm piloting from in cockpit or down below. For that reason I've installed a few USB charger points and in fact putting in at least one more.
Today is like having a whole team of navigators below at a huge chart table doing the hard work of keeping track of your boat while you concentrate of keeping a lookout.
The ship mounted CP used to be the primary but now it's hard to say which is the back up, today. I like an Ipad for my main navigation, piloting and route planning but phones are becoming more useful for navigation.
I like separate software for it's unique functions and settings and even opinions. I can set different reference bearings on screens that help me pilot.
Portability of these devices is important to me because weather and sailing conditions determine where I'm piloting from in cockpit or down below. For that reason I've installed a few USB charger points and in fact putting in at least one more.
Today is like having a whole team of navigators below at a huge chart table doing the hard work of keeping track of your boat while you concentrate of keeping a lookout.
I see your first mate has a watchful eye on GPS! My God what did sailors do before GPS, chart plotters, etc.?
When I was into sport fishing I always wanted to arrange a fishing tournament without the use of any electronic equipment. I was never able to but what a hoot it would have been. I bet the old salts would have loved it.
Sticking with just electronic nav aides only, the answer is in combinational probability.
The chance of any one device is not working is 50%, either it works or doesn't. The chance of 2 devices not working is ½ * ½ or there is a one in four chance of not having any device working. With 3 devices, the chance of only having one device working is ½ * ½* * ½ or ⅛. And the odds continue to get better.
Yes I do. The gps chip is on the cell phone chip. Cellphone service is not needed, just the cell phone chip.
I know what I did: I sailed less.
When the captain is also the navigator, sailing along a coast with a chart in the cockpit (or below in weather), piloting my location with pencil and rules, taking bearings, was at times, a lot of work.
Our Ipad 2 doesn't, so we have a separate GPS receiver (Garmin Glo).
The next tablet will be GPS enabled. Trouble is, Apple stuff seems (to me) to last forever. This one runs about 8 or more hours a day at home and has since we bought it maybe 8-9 years ago. It hits the floor at least once a day...
They don't break, but they do get to a point where they won't run the current OS and newer programs won't run on them. And they get slow.....
That is true. This one is used for music, movies, internet. It still has the Garmin Blue Chart app installed when nearly new and that works fine. It may finally end up on the boat squirreled away in the chart drawer, the ultimate - drop dead - last gasp,... backup.
I've got this crew below decks.....oh and a sextant, though I only use it offshore....
I don't have this problem because I only sail on a lake. I'm never more than a few dozen miles away from rocks in any direction, and I kinda know which direction to go. If my GPS(s) fail, and I'm not within soundings, I'll just head over there until I can figure it out from paper charts. Most of the lake-shore is soft, anyhow.
As the old folks say around here, you're never more than 700 feet from land when you're on the lake. Of course, that may be straight down.
As the old folks say around here, you're never more than 700 feet from land when you're on the lake. Of course, that may be straight down.
Before the day of cell phone, GPS and all the modern gadgetry, I use to carry a simple radio with A M stations. In an area at night this helped. A young sailor left the radio turned down draining the battery and on top of that lost the charts overboard. I took out my VAstate highways road map to include the Chesapeake Bay triangling two radio A M stations. Got me in safely
I like that. In the NC outerbanks (sound side) I could claim to always be within 20 feet of land. I doubt that will make the admiral happy but my kids do like bad dad-jokes.I don't have this problem because I only sail on a lake. I'm never more than a few dozen miles away from rocks in any direction, and I kinda know which direction to go. If my GPS(s) fail, and I'm not within soundings, I'll just head over there until I can figure it out from paper charts. Most of the lake-shore is soft, anyhow.
As the old folks say around here, you're never more than 700 feet from land when you're on the lake. Of course, that may be straight down.
Jackdaw, when was the last time you had a GPS failure? i am not talking of individual units but the space borne system. I am going to guess never. Apart from localized military exercises where low power jamming might be practiced but will be NOTAM`d. The DOD have a responsibility for the system and its integrity, which is why every aircraft flying is dependent upon GPS. In the old days when i was in the military, we used to gun up the GPS sets with secret codes that would make it immune from deliberate spoofing and provide a better positional accuracy, that stopped a very long time ago.
An extra receiver, compass, charts and the knowledge of how to use them is all you need.
An extra receiver, compass, charts and the knowledge of how to use them is all you need.
My left eye is a backup to my dominate right eye for my navigation on the lake...
This was my VFR backup in the T-37...
I guess it would work just as well on the water
I guess it would work just as well on the water