A new report just dropped (to re-animate this thread)
R.I.N. " The Impacts of GNSS Interference on Maritime Safety" - downloadable…
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It’s BIG and a bit of a slog through the survey, but Ch 4, 5, 6 and onward is the really good stuff.
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Thx. Good stuff.
Summary is no fix for the problem, a warning at best
Been many threads here on GNSS spoofing, turns out we barely scratched the surface.
From the report:
The evidence for unnecessary dependencies between GNSS receivers and a variety of electronic systems onboard a modern vessel, many of which do not need to be connected to GNSS data to provide their primary function. These systems include the RADAR, VHF/MF/HF radios, NAVTEX, ship’s speed log, ship’s clock, and satellite communications systems.
On some recreation vessels even the whistle uses a GNSS signal.
A ship’s whistle connected to GNSS data in order to select the correct whistle sounding pattern based on the motion of the vessel may not operate properly during GNSS interference. The complete absence of GNSS data due to jamming may result in the whistle not sounding correctly, or at all.
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From Charles Perrow, the systems are tightly coupled - no simple or easy fix.
As crew you should certainly know whats taking a gps signal
Look at wiring diagram
How many radars are JUST radars anymore? The ones I use now can overlay charts, AIS targets, courses, and waypoints on the display. Obviously that all craps out without GPS, although MARPA/ARPA should still work if the heading feed is good. One should know how to clean up the display to just a radar when that happens.
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It really sucks to be entering a tight passage with a lot of turns and bouys in a snow storm with a big following sea and a strong fair current running - think False Pass - and then lose all heading reference. Every piece of gear in the wheelhouse starts alarming, the autopilot stops working. The radar pictures start rotating. No alternate heading reference available.
regulations should not allow this.
Can’t just dump a big steaming pile in the wheelhouse and expect the crew to deal with it. This problem was created at a higher level, must be fixed at a higher level.
Might be able to mitigate to some degree but this won’t be fixed by training shipboard.
They don’t!
2 Shipborne navigational equipment and systems
But the ‘small tug with huge cargo barge’ concept is designed to avoid such regs (and expenses) which might might apply to an actual ship of the same cargo capacity.
(especially on such an open water trade route as you allude to)
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OpenCPN at least allows multiple redundant inputs of heading and anything else actually and they can be ordered in preference. That said, your scenario sounds truly frightening, you hardly have time to rearrange anything.
but it all stops at the same time
We teach in DP training,
DGPS, the most accurate pos ref and the most unreliable
GPS aside, if you lose your heading data the radar overlay on the chart loses synch between the radar and the chart.
How does the chart know where you are on it without gps?
I’ve seen this loss of heading input problem several times.
How does the radar or autopilot or chartplotter know your heading, or that you are turning, without input from the satellite compass (which is gps) or gyro or a magnetic compass?
Traditional gyros are a thing of the past on American tugs. They are too expensive to buy and repair. I rarely see them on tugs anymore.
Even my phone has a solid state gyro on a chip. I do not understand why autopilots, radars, chartplotters, etc. do not have these little gyros on a chip as at least an automatic emergency back up.
I recall gyro failures years ago. I recall falling automatic switches that were supposed to switch from gyro to sat compass if the gyro failed, and I recall gyros that were working fine, but those automatic switches failing due to loss of power supply or overheating blocking the signal from the gyro and the sat compass.
Most magnetic compasses on small vessels are long overdue for being re-swung. Or the provisions for switching the autopilot to magnetic compass are horrendously complicated and difficult to do in an emergency.
On a deep-sea SOLAS vessel the connection between the GPS and the gyro compass is the speed and latitude corrections. If the ship’s gyro lost the GNSS signal the gyro would still work but it might have an error. Typically less than 2° IIRC. The correction could be entered manually on the compass I’ve seen.
It doesn’t, which also messes up the radar overlay. You can still have a mess even if you know where you are but not which way you are pointed 
In a busy area, traffic, navigation, communication etc the bridge team could be at, say, 85% of (information processing) capacity. If the GNSS fails the work load is going to suddenly jump as the failure cascades through the systems.
The fact that there are workarounds for each specific failure is not the point.
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That is so true.
All the alarms are a huge distraction.
When GPS signal is lost: The DSC enabled radios are alarming. The radars are alarming. The GPSes are alarming. The Sat Compass is alarming. The AIS is alarming. The chart plotters may be alarming. The autopilot is alarming. Figuring out where all the alarms are coming from is a lot of work. So is figuring out how to shut all the alarms down.
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