GPS

[Blue5]

Having been trained when radio aids really were aids (Decca was still plotted on Lattice charts) I am basically very much a 2b pencil and chart man, but there is no doubt that GPS is a boon and after several years with a basic hand held I have craduated to a plotter and as a back up a lap top with GPS and a different charting package (a back up is not independant if it shares resources). One of the handhelds will sit in the grab bag and the other in the chart table drawer. I will of course keep my paper charts, there are times when seeing the big picture clerly has it's plus points.

I was also trained to do pilotage in conditions where having a chart at hand was not practical so also can do such detailed preplanning with clearing bearings wheel over points etc.

I see no problems in using modern tools to do the job if you both ensure back up and the ability to revert to first principles

Just dont forget the pack of AA batteries for the grab bag as well. H/H GPS are a brilliant bit of kit, the weak link is the batteries

 

[wotayottie]

I fly light aircraft.

For long distance sailing can the same be said? It seems to me with kit like Raymarine's E series driven by GPS with another backup there is very little need for traditional navigation techniques and while there is a risk in extreme of it all failing presumably the risk is very small.

What do people think?

I sail a reasonable amount each year, more than many but less than others. In the 20 years I've been doing this I have only lost GPS service at a time I needed it twice. Both times were in electrical storms. Probably another 20 times when I havent needed it and interestingly those times have been recent. Maybe something to do with the age of the satellites.

I have never lost GPS service because of boat electrical supply problems.

Personally I wouldnt sail without paper charts but thats an issue about course planning / plotting etc not position finding. For position finding I have never used anything but GPS or compass fixes with the exception of my YM practical exam when I did my one and only EP.

In short I use GPS but am not bothered about plotters.

 

[wotayottie]

In true blue water, I really dont see any alternative. GPS can be powered by AA batteries and you dont need a plotter which is only going to show sea anyway.. YOu can have two of the GPS cheaply. You dont need a position more than once or twice per day. So what possible argument other than sentimentality is there for the sextant or the astrolabe etc.

Sure you could use a horse to visit your friends 50 milers away but why do so when there is the car. Its the same with sextants and GPS.

 

[maxi77]

In true blue water, I really dont see any alternative. GPS can be powered by AA batteries and you dont need a plotter which is only going to show sea anyway.. YOu can have two of the GPS cheaply. You dont need a position more than once or twice per day. So what possible argument other than sentimentality is there for the sextant or the astrolabe etc.

Sure you could use a horse to visit your friends 50 milers away but why do so when there is the car. Its the same with sextants and GPS.

I must admit having known people who have suffered total electrical failure I think there is a limit to how far I would trust my box of AA batteries. For any significant journey out of sight of land a sextant and a time piece as a back up would seem sensible.

 

[LadyInBed]

In any case, there are issues around feeling a sense of continuity with the past!

How right you are, there's nothing like hanging your back-side over the sea for a dump!

 

[Evadne]

I like to plot my position on a paper chart, if it is needed. Plotters are to small to give much of an overview for passage planning anyway.

Most of my sailing is in my local back yard, so Mk1 eyeball and a quick jot in the log is the norm there, but on longer passages I keep an hourly log and plot a fix.

The handheld GPS is mostly used as a virtual compass, by giving range and bearing off otherwise invisible landmarks, if there are not enough in sight too take a normal compass fix. Our "little friend" is also used to estimate ETA, and is more objective than I am. It has also been used to display a course to steer, when SWMBO is too seasick to steer a course while I navigate, although we try to avoid that these days

I think this is the best of both worlds, using the accuracy of modern system while not forgetting why I am sailing to my destination, instead of driving or catching the bus. I can understand others wanting to play with the boys toys on offer today, but it is too much like being at work for me.

 

[alahol2]

Reading this, and remebering an earlier thread about logs, makes me realise that my log impellor fouls up so often that I now hardly ever bother with it. I rely on the GPS to give me speed readings if I need them. If the GPS failed now, I couldn't plot dead reckoning because I've no log. How many others would be in the same position? Actually I have got an old manual Wasp log buried at the bottom of a locker somewhere aboard which I guess I could extract. Why won't someone bring back the old trailing electronic log? or offer a trailing impellor for the current crop of logs? Sorry I'm rambling...

 

[alexrunic]

I think it's madness not to go to sea without paper charts as mentioned you could lose power or your gps could go down. ok you can carry back ups but what happens if the gps system goes down either because the Americans have a tecnical problem like they are warning of problems in the next few years because of lack of funding. Also terrorists could jam the signals.

you can't beat keeping an hourly log with a mark on the chart, least you know where you were an hour ago and what course you should of been on. It's better to be safe than sorry.

I have nothing against electronics and do use a gps some times I just would not want to trust my life on it

 

[wotayottie]

what happens if the gps system goes down either because the Americans have a tecnical problem like they are warning of problems in the next few years because of lack of funding. Also terrorists could jam the signals.

When did that last happen? has it ever happened? By comparison, when did you last make a mathematical mistake using a sextant? Or find that there was 100% cloud cover for a day or two?

There are risks in going to sea but you need to have a rational view of how great those risks are. I am absolutely convinced that the risk of the gPS system going down is infinitely less than that of me making a cock of a sextant sight and its calculations, let alone that sight never being more accurate than a few miles anyway.

In my personal sailing experience of 20 years I have known 2 boats sunk by lightning, 3 boats burnt to the waterline and 2 boats lose their keels ( one Westerly one Colvic). Numerous boats disabled through engine problems. I do not know of a single boat lost by over reliance on electronics.

 

[alexrunic]

When did that last happen? has it ever happened? By comparison, when did you last make a mathematical mistake using a sextant? Or find that there was 100% cloud cover for a day or two?

There are risks in going to sea but you need to have a rational view of how great those risks are. I am absolutely convinced that the risk of the gPS system going down is infinitely less than that of me making a cock of a sextant sight and its calculations, let alone that sight never being more accurate than a few miles anyway.

In my personal sailing experience of 20 years I have known 2 boats sunk by lightning, 3 boats burnt to the waterline and 2 boats lose their keels ( one Westerly one Colvic). Numerous boats disabled through engine problems. I do not know of a single boat lost by over reliance on electronics.

I think you have miss understood me all I'm saying is have paper charts on board and keep a log so if the electronics go down you know where you are. gps is a useful tool but like every method of navigation it is not fool proof. As to the GPS System going down I have read a couple of reports on the lack of funding and there could be problems with the system over the next few years. I certainly would not cross an ocean with out a sextant and the knowledge to use if. But for coastal sailing I think keeping a log is sufficient.

 

[Deleted member 36384]

...... do not know of a single boat lost by over reliance on electronics.

Mmmm - the big power boat a couple of years ago, brand new, straight out of Cowes, on autopilot following a plotter route and ran straight into a post the position of which was also a way point. It sank with much embarrassment.... and there are quite a few others classed as GPS Assisted Collisions.

All human error of course!

 

[Ubergeekian]

Actually I have got an old manual Wasp log buried at the bottom of a locker somewhere aboard which I guess I could extract. Why won't someone bring back the old trailing electronic log? or offer a trailing impellor for the current crop of logs? Sorry I'm rambling...

I would never be without my Walker's Knotmaster. There is something deeply satisfying about a mechanical record of miles sailed, and at night the whirring line is very friendly.

 

[wotayottie]

I think you have miss understood me all I'm saying is have paper charts on board and keep a log so if the electronics go down you know where you are. gps is a useful tool but like every method of navigation it is not fool proof. As to the GPS System going down I have read a couple of reports on the lack of funding and there could be problems with the system over the next few years. I certainly would not cross an ocean with out a sextant and the knowledge to use if. But for coastal sailing I think keeping a log is sufficient.

Agree 100% about keeping a log but the OP was raising the question of GPS alone or inertial nav etc as used in planes.

To me there are two seperate issues - do you rely on GPS as the primary fix system (answer yes) and do you use electronically displayed charts ( personal choice but in my case - no).

It always amuses me to hear people arguing about the risk GPS system shut downs when its happened less frequently than people winning the lottery, or lightning strikes or Gordon Brown getting something right. So you find people crossing the Atlantic with a sextant to back up the GPS but no watermaker. Or no Epirb. Or no spare sails.

 

[wotayottie]

All human error of course!

darwin at work. the electronics worked splendidly, exactly as set up to do by the idiot driving the boat.

 

[smartcom]

There are problems with GPS, not so much offshore but in coastal waters, with interference or jamming. This is why there is a strong push from Trinity House and others to set up eLoran as an alternative - not quite as accurate, but unlikely to fail at the same time as GPS.
Even if we forget about intentional military jamming exercises, GPS signals are very weak and easy to jam - see my column in December's Yachting Monthly on this. Recently faulty electronics on a ship caused jamming within a 100m radius. A lower range problem is faulty amplified TV aerials and TV broadcast stations. Also New York taxis are often fitted with jammers (bought over the web) to hide their position from their control centre, so they can pick up high value fares even if they are not the closest cab.

It is interesting to see that sextant sales have boomed over the last year or so - see the news item about the Mini-Transat boat that got lost at www.winastro.com

 

[Neil_Y]

I used to fly (small planes) some time ago and the one big difference is all the aircraft I flew were well maintained and not subject to DIY electrics and salt water!

Electronics can and do fail quite often on boats, the environment is not nice. I've had three seperate gps systems fail within 12 hours of each other, leaving me slightly nervously approaching a foreign coast for the first time. Not exactly sure of where I was I had to resort to some hands on navigation. The sextant is a great tool and very reasuring.

I was also taught to fly by a WWII spitfire pilot before gps's so it was chimney and pylon navigation by an expert!

 

[electrosys]

"One of the handhelds will sit in the grab bag ...."
Just dont forget the pack of AA batteries for the grab bag as well. H/H GPS are a brilliant bit of kit, the weak link is the batteries

OK - so there we are, flopping around in the middle of the oggin in our liferaft, and we know our position to within a few metres. Great - what possible use is that information ?
I think I'd rather have an extra can of water and a bar of chocolate - or a couple of extra flares.

 

[Dockhead]

Fascinating how different everyone's approach is.

Mine is a guess still another one. I am a little old-fashioned, and pretty much steeped in paper chart work. Until quite recently I never had a chart plotter at the helm (and I promptly ran aground the first day I did, an excellent lesson). My primary GPS for years was one of those wrist-mounted runner's units the size of a wristwatch, which gave the basics -- SOG, COG, bearing and distance to a waypoint. That and a paper chart and I was happy.

Now I do have a chart plotter at the helm and I love it. It is tremendously good for awareness of your position, hazards, and general orientation. I always have a full set of paper charts on board (I think it's unseamanlike and perhaps illegal not to) but I rarely use them underway.

But I still find that I can't do my pre-departure passage planning and pilotage study without paper charts. It's just not the same on a screen. So for me the paper charts get used before getting under way, to study the passage, choose waypoints, study pilotage at the destination (together with a good pilot book of course, which I would also not want in electronic form), and generally to orient myself before setting off.

So on my boat, both paper and electronic are essential, at least to me. I also keep a handheld GPS or two around, as backup.