GPS Jamming

[ETwhat?]

So during joint NATO exercises the GPS signal is effectively interupted.http://www.bbc.co.uk/news/uk-scotlan...lands-17574089 obviously during exercises they can publish the details and only use the system for short periods, but it is possible that they could use it where ever and whenever there was a tactical advantage. Apart from relying on other systems, how do people feel about the idea of going back to proper (traditional) navigation?

[CharlieDelta]

I imagine they can, and this is why we still have backup methods.

Proper navigation? Surely using the most accurate means of position fixing available is proper navigation?

[ETwhat?]

I imagine they can, and this is why we still have backup methods.

Proper navigation? Surely using the most accurate means of position fixing available is proper navigation?

So what back up methods do you use, and are they tested in the same way back up generators etc are, How would having to rely on these affect the running of the bridge? given that a sustained campaing could affect an area for a long time, and therefore everything else has to keep going aswell.

[gadget123]

So what back up methods do you use, and are they tested in the same way back up generators etc are, How would having to rely on these affect the running of the bridge? given that a sustained campaing could affect an area for a long time, and therefore everything else has to keep going aswell.

Methods of position fixing other than GPS
Radar
Echo sounder
Astro
Compass bearings
HSA
Running fix

I like to think I could navigate quite happily with out GPS. As for going back to navigating properly I like to think we have always navigated properly.

[CharlieDelta]

So what back up methods do you use, and are they tested in the same way back up generators etc are

Celestial. No back up required, apart from not breaking your sextant.
Radar. Generally kept in working order.
Visual bearings. Don't break the compass.
Horizontal angles by compass bearings/horizontal sextant angles. Again, don't break the sextant.
Vertical sextant angles. Don't break the sextant.
LORAN C is still available somewhere in the world I'm sure.

As gadget123 says, you can also get a crude position line by a line of soundings, particularly with a steeply sloping seabed.

How would having to rely on these affect the running of the bridge? given that a sustained campaing could affect an area for a long time, and therefore everything else has to keep going aswell.

I imagine that, should it happen, merchant ships will avoid any danger areas unless they are taken up from trade. In that case, ships would be assigned naval personnel and fitted with the appropriate equipment.

Loss of GPS for ocean navigation would not add any significant workload, apart from taking and reducing sights and running ahead. Sure, you might not arrive exactly to-the-minute, but you'll get within at most a few miles of where you want to be at landfall and you can sort it out from there. For coastal navigation, theoretically, nothing should change since you shouldn't be relying on GPS in coastal waters.

Proper navigation does not mean getting all salty with a pipe and a sextant. It means being aware of the position of your ship, and what to do to get to your destination. GPS, while subject to error, is by far more accurate for ocean navigation and there's nothing improper in using it.

[ETwhat?]

I like to think I could navigate quite happily with out GPS. As for going back to navigating properly I like to think we have always navigated properly.

Most of your other methods require the ability to 'see' land, obviously not astro but have you run old navigation along a chart for a few days and then compared where you thought you are with where the GPs tells you, just to see how accurate you are. As for navigating properly the basis of traditional navigation is directing the movement from one place to another, however with a GPS you dont do that, you simply take a new starting postion for each decision, and that postion has no consideration on the pervious data,

[gadget123]

Most of your other methods require the ability to 'see' land, obviously not astro but have you run old navigation along a chart for a few days and then compared where you thought you are with where the GPs tells you, just to see how accurate you are. As for navigating properly the basis of traditional navigation is directing the movement from one place to another, however with a GPS you dont do that, you simply take a new starting postion for each decision, and that postion has no consideration on the pervious data,

You can take sites with a reasonable level of accuracy, like charlie delta said you only need to be within a few miles where you need to be when you make landfall then you can get a decent fix on the radar and take it from there.

I have always been taught to not use the GPS as your main position fixing method when in sight of land anyway. Only tend to use it as an occasional cross check.

[ETwhat?]

SO the opinion is that really a GPS is a nice thing to have as a cross check but really can be done without, excellent, next time its not working i will know to put it on the 'to be done during a quiet afternoon if there isnt anything good on tv' jobs list.

[bobofinga]

Have to dust off the ole Sextant but I'm sure we'd cope without any problems.

We have a young Captain who likes to test us on our positon fixing by covering up all the GPS feeds on the Bridge. Its A LOT easier than you'd think especially since in the North Sea the majority of time you can find a Platform or Rig to get a bearing/range from.

[CharlieDelta]

SO the opinion is that really a GPS is a nice thing to have as a cross check but really can be done without, excellent, next time its not working i will know to put it on the 'to be done during a quiet afternoon if there isnt anything good on tv' jobs list.

Nice try. We can live without it, but why put off fixing a piece of equipment that can give you a very accurate position in comparison to other methods? Or indeed, why allow yourself to navigate using only a single method of fixing because the ETO can't be bothered? Can't be fixed until we're in port? Not a receiver problem? Fine. At least we tried.

It has been drummed into me, and I hope all deck cadets, that professionalism is paramount in this industry. Passage plans should be meticulous while allowing for deviation where necessary. The ship's structure should be maintained proactively, and one should take pride in one's ship. On the bridge, we want every possible means of position fixing available to us and every conceivable tool for collision avoidance functioning and available. Paraphrasing from one of my lecturers: "slipshod work should not be tolerated in any circumstances".