GPS failure and the sextant.

[capnsensible]

This topic comes up from time to time so I would like to ask how many people have had their GPS fail?

I will happily begin! Like sales reps that do loadsa driving and see many accidents, I get to do lots of time at sea so probably not totally representative, however:

Several times had aerial failure. Bit vulnerable on the pushpit, have had thing broken by inadvertant use as a handhold by sufferers of the mal de mer. Notably westbound round Trafalgar in rain filled visibility and somewhat bumpy sea....F9. Happiness is an echo sounder.

Yesterday I fitted a new chartplotter to one of my yachts, old garmin had continual aerial snags.

For those who wisely say carry a hand held as back up, ever had a battery meltdown (AA)? Sadly, at the cost of ruination, twice.

A good friend, eastbound and 10 days from Azores, starter motor blow out. No electricity at all, imagine that. Fridge, lights, the lot. Er and no hand held.

So it does happen. Anyone else??


It may be worth noting that for those seeking promotion within the commercial world of boats, it is necessary to qualify as YM Ocean in a number of cases, for example Chief Mate over 3000. Obviously this is a specialist area but other employers do rate the lads and lasses who go the extra mile.

So for leisure sailors, is it worth it? Take 2 handhelds, will never work at sea, vast majority of people.

Answer is probably no......but I enjoy astro and am very pleased when I get it right!

Your thoughts??

CS

 

[TimBennet]

But how many incidents of GPS failure have you experienced compared to complete Astro failure? Are you telling us that completely overcast skies are really less common than total electrical failure? Are sextants not more venerable to bashing / water damage than a rugged, immersion proof handheld GPS?

I remember ocean racing in the 70's and 80's where we wondering where we were was our constant concern. During the winter monsoons running ships along the coast of China, I remember months passing without a break in the grey total cloud cover.

Consol, Decca, Loran, Omega and RDF were seen as a godsends in their day, Transit satnav was a huge step up, but GPS changed everything again.

I have never had a complete power failure on my boat, and when hopping on other boats, there's always my Garmin 76 in my bag with a box of AA cells, and despite being lugged around all over the place, it has never missed a beat.

If on an ocean crossing you did suffer the trauma of a complete and absolute total GPS failure, if it was in the last 7 to 10 days of the crossing, you could dead reckon from there. There were loads of times people have approached a coast with total overcast skies lasting for a week. It's not relaxing, but it's been done thousands of times.

Astro has its place, but lets not get starry eyed about it.

 

[chinita]

I don't have a sextant but, just for fun, I sailed from Lagos to Lymington without GPS.

Just Dead Reckoning.

No problems encountered, perhaps I was just lucky, or perhaps I felt comfortable knowing I could switch the GPS back on!

I do remember, though, being a bit relieved at seeing the loom of la Jument fine on the port bow

 

[oldvarnish]

I remember ocean racing in the 70's and 80's where we wondering where we were was our constant concern.

Wasn't that part of the challenge, and wasn't it part of the eventual satisfaction of an enjoyable and satisfying cruise?

(I'm not disagreeing with anything you say, by the way)

 

[nortada]

This topic comes up from time to time so I would like to ask how many people have had their GPS fail?

I will happily begin! Like sales reps that do loadsa driving and see many accidents, I get to do lots of time at sea so probably not totally representative, however:

Several times had aerial failure. Bit vulnerable on the pushpit, have had thing broken by inadvertant use as a handhold by sufferers of the mal de mer. Notably westbound round Trafalgar in rain filled visibility and somewhat bumpy sea....F9. Happiness is an echo sounder.

Yesterday I fitted a new chartplotter to one of my yachts, old garmin had continual aerial snags.

For those who wisely say carry a hand held as back up, ever had a battery meltdown (AA)? Sadly, at the cost of ruination, twice.

A good friend, eastbound and 10 days from Azores, starter motor blow out. No electricity at all, imagine that. Fridge, lights, the lot. Er and no hand held.

So it does happen. Anyone else??


It may be worth noting that for those seeking promotion within the commercial world of boats, it is necessary to qualify as YM Ocean in a number of cases, for example Chief Mate over 3000. Obviously this is a specialist area but other employers do rate the lads and lasses who go the extra mile.

So for leisure sailors, is it worth it? Take 2 handhelds, will never work at sea, vast majority of people.

Answer is probably no......but I enjoy astro and am very pleased when I get it right!

Your thoughts??

CS

Good post - agree your views. We have 2 ship powered GPSs on board & 2 handhelds. Over 16 years (much as live-aboards) we have never had GPS failure. We also have a sextant - professional at cocking up a sight. Best effort about 4 miles within known position - worst proved Siberia was just off the coast of Cadiz!

 

[jordanbasset]

Have had fixed one go down a couple of times, the back up hand held worked fine on those occasions. I suppose it's possible the batteries could go flat and I could have forgotten to have spare batteries etc, but I think it is more likely to be cloudy than have that happen.

 

[TimBennet]

Wasn't that part of the challenge, and wasn't it part of the eventual satisfaction of an enjoyable and satisfying cruise?

Yes I'm really glad I started back then. But it was easy to apply yourself and accept the enormous strain of not knowing where you were, because having virtually nothing to help you navigate was 'state of the art' back then.

I just recognise that traditional navigation had severe limitations. Now we concern ourselves with deciding where we are, but back then we were only concerned with deciding whether our positional 'circles of uncertainty' overlapped with any places where we might be 'standing into danger'.

There are lots of risks in sailing and they all need to be evaluated carefully. You can then take steps to mitigate them as much as is both possible and necessary. It requires an assessment of both likelihood and consequence. And when formulating 'Plan B', it has to be viable and realistic.

So for most people, carrying a plastic sextant and a copy of 'know the game astronavigation' isn't a viable or realistic back-up to the probably avoidable problem of total GPS outage for weeks on end. If you are not a well practiced practitioner of astro navigation, then any results you get could well be matched by a more dependable bout of dead reckoning. If you are capable of picking up a sextant the moment you loose all GPS capability, then you have obviously been spending your time on that (because you want to) instead of doing routine maintenance on your boat's wiring system.

 

[capnsensible]

So for most people, carrying a plastic sextant and a copy of 'know the game astronavigation' isn't a viable or realistic back-up to the probably avoidable problem of total GPS outage for weeks on end. If you are not a well practiced practitioner of astro navigation, then any results you get could well be matched by a more dependable bout of dead reckoning. If you are capable of picking up a sextant the moment you loose all GPS capability, then you have obviously been spending your time on that (because you want to) instead of doing routine maintenance on your boat's wiring system.

Tim I think you miss my point. I have asked if you have ever had that total failure. You can blame lack of maintenance as much as you like, but like plane crashes, 5h1t happens. Then what do you do?

Navigate with caution? Have 2 sextants, I could go on.....

Anyway, seems like plenty of people are still interested enough to want to learn, notably an awful lot of not British. Seems to be very popular amongst Portugese and Spanish english speaking sailors. Dont know why.

 

[geoid96]

Carrying multiple GNSS receivers can provide good redundancy to cover for individual unit failure. However a measurable risk to all satellite based positioning systems is interference. This might be man-made or due to ionospheric disturbance. Either it way would be likely to effect all receivers equally. The risk of complete failure is small, but I consider still sufficient for me to run DR and astro in parallel. One big advantage of doing this on passage is that it can be used to ‘calibrate’ the DR and improve its reliability if it needs to be relied on.

 

[TimBennet]

I have asked if you have ever had that total failure.

The reply is "only with astro".

Every time time there were thick overcast stormy skies, or high pressure gloomy grey skies when you thought you could make out a bright patch in the sky, or when there was a more pressing problem at dusk making you miss twilight, or . . . etc.

 

[capnsensible]

The reply is "only with astro".

Every time time there were thick overcast stormy skies, or high pressure gloomy grey skies when you thought you could make out a bright patch in the sky, or when there was a more pressing problem at dusk making you miss twilight, or . . . etc.

Fair answer.....but not to my question! Unsurprisingly, I am familiar with overcast.

The question is who else has had aeriel destruction, battery melt, engine and therefore charging knackered. Or anything else.

Appreciate your point but........

 

[Neil]

I bought a sextant, and learned how to use it just for the pleasure of it. Not sure I'd be happy putting it in the boat - wouldn't want to mare its pristine appearance!

Having said, should I ever undertake an oceanic passage, I would want to be able to say to myself that I did it 'for real' (even though I'd double-check my answer with the GPS )

 

[oldbilbo]

Yes I'm really glad I started back then. But it was easy to apply yourself and accept the enormous strain of not knowing where you were, because having virtually nothing to help you navigate was 'state of the art' back then.

I just recognise that traditional navigation had severe limitations. Now we concern ourselves with deciding where we are, but back then we were only concerned with deciding whether our positional 'circles of uncertainty' overlapped with any places where we might be 'standing into danger'.

There are lots of risks in sailing and they all need to be evaluated carefully. You can then take steps to mitigate them as much as is both possible and necessary. It requires an assessment of both likelihood and consequence. And when formulating 'Plan B', it has to be viable and realistic.

So for most people, carrying a plastic sextant and a copy of 'know the game astronavigation' isn't a viable or realistic back-up to the probably avoidable problem of total GPS outage for weeks on end. If you are not a well practiced practitioner of astro navigation, then any results you get could well be matched by a more dependable bout of dead reckoning. If you are capable of picking up a sextant the moment you loose all GPS capability, then you have obviously been spending your time on that (because you want to) instead of doing routine maintenance on your boat's wiring system.

All valid. And also much of what was posted above this.

Astro is just one of the 'systems' available to the conscientious small boat nav. The widely-agreed requirement - and that encouraged by the SOLAS publications - is the capacity to use a reversionary system to 'get you home' when and not 'if' a primary system fails for some reason. And they do....

'Capacity' means both carrying the kit and having the knowhow to use it effectively. Professionals are directed as to what they must have, and must satisfy the relevant authorities. Non-professionals need only satisfy themselves, by and large, that what 'capacity' they have is up to snuff.

GPS and radar and DR would IMHO suffice for most coastal/offshore purposes. Should there be total and irrevocable electrical failure on an ocean passage, then astro capability becomes highly desireable - and that's probably why the Yachtmaster Standards Panel members still believe, in their massive experience, that someone doing this 'profesionally' needs to be able to turn his/her hand to wielding a sextant when so required. Again, an 'amateur' can make his own choices.

Useful DR implies a properly-corrected steering compass, a calibrated distance log, and a meticulously-kept 'navigation log' record of courses, times and distances. Producing reliable DR from a manual DR plot is not as simple as it sounds, as anyone who has had to learn and demonstrate the process as part of a pro nav training will tell you.

I've sailed this year on a new and very expensive yot, with several very expensive compasses - and not a sign of a compass deviation card or certificate of residual errors from a compass adjuster to be found. Does it matter? If I were heading off on the ARC, I would certainly want that info on board, and the means of error-checking as I went along. And if one suffered total electrical failure, which happens, I'd want the 'capacity' not only to put a reasonable fix on the chart every now and then, but also want some means of getting fresh water out of the electrically-pumped taps.....

Ultimately, what kit and 'capacity' you carry is very much down to you and your comfort zone. However, if others are dependant for their safety on your judgement, then responsibility - moral and legal - comes into the picture.

 

[peter2407]

Celestial Nav training - recommendation near Solent?

Hi - about time I learned to do celestial nav properly. Any recommendations near the Solent?

Edit - sorry, meant to post as a new topic.

 

[Wansworth]

I don't have a sextant but, just for fun, I sailed from Lagos to Lymington without GPS.

Just Dead Reckoning.

No problems encountered, perhaps I was just lucky, or perhaps I felt comfortable knowing I could switch the GPS back on!

I do remember, though, being a bit relieved at seeing the loom of la Jument fine on the port bow

There is also mans inbuilt sense of where he but all these gadgets means he does not need them so they become unreliable.I served with on skipper who navigated up and down the coast during the war and he always said you have to have the chart in your head.

 

[Conachair]

Can't remember ever having a gps failure. I have a sextant onboard and tables but really don't think GPS failure is high up the list of bad things possible offshore. If you count a phone and nexus 7 there are 4 gps's onboard. A daily fix any of the batts will easily make it across an ocean.

 

[Fascadale]

I lost all electric power coming into the Sanday Sound (Orkney) from the east. It was a very murky day with the land, both on Sanday and on Stronsay, low lying and featureless. It would have been very difficult to have got a visual fix.

I was very pleased when the eTrex fired up and gave me a position.

I'm doing the Ocean theory course at the moment. If I ever master the complexities of it all I think it will make me a more "complete" seagoer. There is a bit of intellectual curiosity involved, and I like the idea of not being so dependent on electronics. (But I really hope never to be dependent on my ability to astro navigate)

 

[oldvarnish]

A daily fix any of the batts will easily make it across an ocean.

I have a friend whose proud boast is that he got from Cape Horn to Falmouth on one set of AA batteries. He only switched on at noon, and only long enough to get a fix.

I haven't as much ocean experience as some, but I find that when you're out there you soon realise that 'precisely' where you are is of little importance.

 

[AndrewB]

This topic comes up from time to time so I would like to ask how many people have had their GPS fail?

... Several times had aerial failure. Bit vulnerable on the pushpit, have had thing broken by inadvertant use as a handhold by sufferers of the mal de mer.

... For those who wisely say carry a hand held as back up, ever had a battery meltdown (AA)? Sadly, at the cost of ruination, twice.

... So it does happen. Anyone else??

Yes, likewise several aerial failures. Being struck by lightning doesn't improve them, either.

Never had the backup handheld (ETrek) fail. But on four occasions over the last 10 years I've seen GPS go down altogether, for up to 15 minutes. The US practicing wargames, I've been told. (Apparently they have the ability to "target" GPS-blind areas). Just as long as they don't decide to do it for real.

 

[Deleted member 36384]

Total failure of GPS; a few times, I don't carry a battery operated back up GPS. These days I sail coastal waters. Over the last 4 years: antenna failure - water ingress, antenna cable failure - poor quality join (I discovered tin foil was used to bridge the screen join), failed antenna wire to plotter connector - frequent demounting plotter caused the antenna to fatigue.

So 3 in four years, coastal sailing, plotter removed from cockpit when not in use for security, weekend sailing at least 1 weekend per month for 7 months per year. The GPS installation is probably at least 12 years old. The plotter keeps on going, but as you can see its the antenna and co axial cable that have given me issues.