We made our minds to head off to Whangaparapara. This was mainly up wind and hence required us to motor all the way. For the first section we were reasonably sheltered and had flat seas. Once we reached the open sea we had to head directly into the swell which made the ride quite bumpy.
Not long into this leg we lost the GPS signal into our main chart plotter. My first thought was that a cable had come loose so after making sure our heading was safe I took off the panel and checked all the connectors. This didn’t resolve the issue.
I then powered up my portable backup GPS. It came on but it could not pick up a GPS signal. I then checked the GPS reading from the AIS using the computer. It too was registering no GPS signal.
So I had three separate GPS devices all indicating that there was no GPS signal reaching the boat. So we either had a systemic issue or the GPS satellites had been turned off. The latter possibility was quite ominous. Both the reason for switch off and the consequence to boaters was quite scary. To double check I called the coast guard who independently checked this for us. They came back and reassured us the service was up and running.
I now had to figure out why all three of my devices were not picking up a signal. The first thing I tried was turning off the AIS. The GPS signals were now being received by the other two units. That was weird. Getting to our anchorage safely was the priority so I left the troubleshooting till later and took us in.
After lunch and a rest I turned my mind back to the GPS problem. I must admit I was feeling a bit despondent as I was beginning to feel my new AIS setup was causing more problems than benefits.
It took me about 10 seconds to make a key step towards determining cause. The GPS antenna for the AIS had proven itself to work just fine indoors so I hadn’t yet fixed it anywhere. In the bumpy seas it had fallen over and come up against the stainless steel pole at the front of our cabin which supports the mast. As a matter of tidiness I picked it up. I noticed that the portable GPS immediately began to register satellite reception. I put the AIS GPS receiver back against the pole and the portable GPS lost satellite reception. This happened even when the portable GPS was disconnected from the boat power. This was also having the same effects on the GPS reception to the main chartplotter as well as the GPS reception of the AIS unit.
So somehow, proximity between the AIS GPS receiver and the mast pole seemed to be jamming all three units even though there was no physical connection. Very, very strange.
Why this happens baffles me. The actual cause lives in the realm of radio reception, antennae and what not. This is an area of science which, to me, seems close to magic and hence best left well alone.
I know how to replicate the problem and I know how to resolve it. I’d be curious to understand root cause but it won’t keep me awake at night not knowing.
The weather never really turned nice so we stayed aboard for the rest of the day. Hopefully today we can get ashore, visit the shop and walk to the nearby hot springs.
We have no internet here, shock horror. I think we can survive for a while but this may incentivise us to move on sooner rather than later.
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