Tech

[PaulRainbow]

What happens when the sat nav goes down?
Without an understanding of the principals you would be stuffed. Or lost.

Main plotter
10.4" tablet
2nd 10.4" tablet
Laptop
2nd Laptop
Phone
Partners phone

All have their own GPS and charts and everything except the plotter has it's own battery.

If they all go down it can only be the GPS satellites have been destroyed by aliens, so i might not want to head for shore anything soon anyway

Oh, when i do decide to brave the alien invasion i'll dig the paper charts out.

 

[boomerangben]

Main plotter
10.4" tablet
2nd 10.4" tablet
Laptop
2nd Laptop
Phone
Partners phone

All have their own GPS and charts and everything except the plotter has it's own battery.

If they all go down it can only be the GPS satellites have been destroyed by aliens, so i might not want to head for shore anything soon anyway

Oh, when i do decide to brave the alien invasion i'll dig the paper charts out.

Sadly, the increasing level of military jamming during exercises means it’s not just aliens…..

https://lloydslist.maritimeintelligence.informa.com/LL1143103/GPS-jamming-poses-threat-to-navigation (Headline only - main article behind a paywall but the source is relevant)

GPS interference and jamming on the increase

I’m not anti GPS at all - I use it every day at work for navigating. But I think we need to be aware jamming goes on. It is very common to read in Notices to Airmen that jamming is happening somewhere in the U.K. yes the effect is far greater to aircraft but it does affect surface vessels too. Even our car has given some odd GPS performance when Joint Warrior operations have been going on locally.

To my mind there is a place for no tech nav in all our tool boxes. After all, plotter manufacturers caveat the use of the their kit and I am pretty sure that not every boat owner checks the notices to mariners

 

[Pye_End]

It’s different on different systems. Read the manual is a great start or get some training. Same as traditional charts really, there’s no substitute for learning.

Didn't think I would get a straight reply. I wouldn't be surprised if key methods can be used across different platforms, so learning how YOU calculate a CTS might be helpful. Or perhaps you just never do it?

However, I have done some searching for the 2 plotters I use (and more), and can find limited useful information at first glance.

I reckon using OpenCPN on a computer with a mouse is probably straightforward (though I havn't tried it yet), but on a tablet or a 5" plotter the picture is rather different.

Did come across this though: Passage planning: Paper or electric? - Yachting Monthly Worth a read, though I know that you will disagree with chunks of it - especially Vector v's Raster issue, and comments about planning on something big so you can see the big picture is better. May well be incorrect for you and the type of sailing you do, but does not mean it is incorrect for others.

 

[lustyd]

I’ve not suggested anything is incorrect, I’ve been correcting people that implied it. Most people these days are quite content to scroll about and get their bearings and pinch zoom makes the raster vector thing moot. If you want to adapt then adapt, if not carry on using what you’re comfortable with but don’t imply that things you’re not comfortable with are inferior because they clearly aren’t.

 

[capnsensible]

 

[KompetentKrew]

If you had planned your voyage properly you wouldn't have fallen off the edge of the chart.

I plan my voyages once underway tho.

 

[Alex_Blackwood]

If you had planned your voyage properly you wouldn't have fallen off the edge of the chart.

Perhaps it is a "Flat Earth" chart!

 

[thinwater]

The Mark I eyeball remains useful for coastal navigation.

 

[LadyInBed]

Would be quite interested to know how you plot an accurate CTS in a cross tide situation on a tablet, for example.

You need a sheet of paper, pencil and a Tide stream book to do that, not a chart.

 

[Pye_End]

You need a sheet of paper, pencil and a Tide stream book to do that, not a chart.

I was taught to plot the tides on a chart (where the distances are readily accessible), and using tidal diamonds (as well as a tidal stream atlas depending on where the best information is). You can tuck various tides away on the chart for later, if useful. I agree you can also do it on a different piece of paper, but 2 posters here say you can do it easily electronically.

Sounds like a plan. Will try it.

 

[capnsensible]

A billion years ago a friend of mine taught me how to navigate from Pompey to Cherbourg using just an Admiralty Tide Stream Atlas.

DECCA for yachts was just being born.

We made it. Several times.

 

[ctva]

When I said, “what if the sat nav goes down”, I meant the satellite systems (multitude of contrôlable and uncontrollable reasons), NOT the individual receiver. I too have a main plotter, two iPhones with charts, an iPad with char and a handheld plotter which will all be useless if the satellite systems fail.

So what then?

 

[capnsensible]

When I said, “what if the sat nav goes down”, I meant the satellite systems (multitude of contrôlable and uncontrollable reasons), NOT the individual receiver. I too have a main plotter, two iPhones with charts, an iPad with char and a handheld plotter which will all be useless if the satellite systems fail.

So what then?

Would you take all that with you if you went on your pals boat? Or on a charter holiday in, say, Greece?

Just sayin.

 

[GHA]

When I said, “what if the sat nav goes down”, I meant the satellite systems (multitude of contrôlable and uncontrollable reasons), NOT the individual receiver. I too have a main plotter, two iPhones with charts, an iPad with char and a handheld plotter which will all be useless if the satellite systems fail.

So what then?

There is quite a strong argument to head offshore for a while, the GPS system has roots deep into society with finance & cell phone towers using the data for precise timing. If the whole system goes down than some crazy stuff will be happening so might well be better to stay away til it calms down a bit...

 

[Tranona]

I was taught to plot the tides on a chart (where the distances are readily accessible), and using tidal diamonds (as well as a tidal stream atlas depending on where the best information is). You can tuck various tides away on the chart for later, if useful. I agree you can also do it on a different piece of paper, but 2 posters here say you can do it easily electronically.

Sounds like a plan. Will try it.

You don't need the chart - as said just the tidal atlas, distance between points and proposed boat speed. No need to draw it out on the chart as taught in the classroom (at least in 1978). Electronic charts have tidal information, some software will allow you to get tidal information over time and date, and some, I believe have an algorithum to do it all for you by putting in your departure and end point, date and boat data to calculate the best time to depart.

 

[boomerangben]

There is quite a strong argument to head offshore for a while, the GPS system has roots deep into society with finance & cell phone towers using the data for precise timing. If the whole system goes down than some crazy stuff will be happening so might well be better to stay away til it calms down a bit...

Absolutely true. GPS signals are line of sight so jamming signals equally so. Over land, jamming signals will fairly quickly be shadowed and otherwise attenuated leaving much of the infrastructure unaffected. But over the sea, attenuation is less so marine users are affected more severely. Jamming is generally going to be localised over relatively small areas - usually associated with protecting surface vessels from missile/drone/airborne attack. But also where we are needing it most - making landfall or avoiding shoal areas. If jamming brought society to a standstill today, it wouldn’t be happening, but it doesn’t, so jamming continues.

It would interesting to see if there was a credible threat made against the RN at Portsmouth/Plymouth/Faslane how quickly jamming would start and shortly thereafter complaints being made. When HMS Queen Elizabeth was in Greenock recently there was jamming used to protect her.

GPS signal jamming as HMS Queen Elizabeth visits

 

[PaulRainbow]

When I said, “what if the sat nav goes down”, I meant the satellite systems (multitude of contrôlable and uncontrollable reasons), NOT the individual receiver. I too have a main plotter, two iPhones with charts, an iPad with char and a handheld plotter which will all be useless if the satellite systems fail.

So what then?

Get the paper charts out.

 

[PaulRainbow]

I was taught to plot the tides on a chart (where the distances are readily accessible), and using tidal diamonds (as well as a tidal stream atlas depending on where the best information is). You can tuck various tides away on the chart for later, if useful. I agree you can also do it on a different piece of paper, but 2 posters here say you can do it easily electronically.

Sounds like a plan. Will try it.

I can do it easily electronically.

I'm at point A and want to get to point B, so i measure the distance between the two points and work out how long it will take to make the passage. Then check the tides and work out how far off of my course the tide will push me. It's then just a case of adding a waypoint to the plotter, or even just clicking where i need to head for and selecting "goto", or whatever you brand of plotter calls that function.

Granted, that may not be easy to do, visually, with a 5" plotter, but that isn't a failure of electronic navigation, that's just you having a plotter too small to do it on. I can do it on my main plotter, which is 12" or on my laptop, which is running Open CPN and is connected to a 40" TV (similar size to an Admiralty leisure chart, which we also carry).

 

[GHA]

Absolutely true. GPS signals are line of sight so jamming signals equally so. Over land, jamming signals will fairly quickly be shadowed and otherwise attenuated leaving much of the infrastructure unaffected. But over the sea, attenuation is less so marine users are affected more severely. Jamming is generally going to be localised over relatively small areas - usually associated with protecting surface vessels from missile/drone/airborne attack. But also where we are needing it most - making landfall or avoiding shoal areas. If jamming brought society to a standstill today, it wouldn’t be happening, but it doesn’t, so jamming continues.

It would interesting to see if there was a credible threat made against the RN at Portsmouth/Plymouth/Faslane how quickly jamming would start and shortly thereafter complaints being made. When HMS Queen Elizabeth was in Greenock recently there was jamming used to protect her.

GPS signal jamming as HMS Queen Elizabeth visits

Post was about the system as a whole going down, not about localised jamming. Ca we all really not do without gps for a while coastal?

 

[Mudisox]

Back in the late 60s/early 70s, we arrived in Falmouth on a Sunday evening for a delivery, only to find that there were no charts onboard. Only place open was a garage, so for that voyage [and many later ones for sheer bravado and total BS] we navigated using the "Esso Road map of South England" . No tide tables but we were at Springs so Dover HT was 1200 GMT and we soon remembered the relevant characteristics of the major lights. You can work out where to go once outside a harbour, it ain't rocket science.