GPS slow to find position

[Tony Button]

On my 2010 Beneteau 35 First, I have a Raymarine Tacktick wireless system with 3 displays on the mast and 3 more in the cockpit and a Raymarine ST70 autopilot. I've noticed that the Speed Over Ground info, which of course relies on the GPS, is often slow to display when the system first boots up. Generally, it takes about 5-10 minutes to show a reading, but last weekend in dense cloud and rain it took about 40 minutes to display. Could it be that the poor weather made the system slow to acquire the satellite signals ? (My Motorola phone GPS got a signal immediately) Is the GPS signal supplied by the autopilot or is it independent ? Has anyone else experienced this and is there anything I can do about it ? Thanks in advance for any help.

[AedanC]

Check to see if the system has a small battery in it to keep the clock alive when the power is turned off. If so it might need replacement. A GPS system can take a long time to get a fix if it doesn’t know the time and date.

[Alan Mighty]

At least two possibilities:

* as AedanC noted, you may need to replace a battery in your GPS antenna (which may be independent or incorporated in something);

or

* you have a GPS antenna that was made marginally out-of-date by the 6 April 2019 week number roll-over. For which see: https://en.wikipedia.org/wiki/GPS_Week_Number_Rollover

Either are strong possibilities for equipment likely to be in a yacht built in or before 2010.

[SeanPatrick]

^What they said.

[fred4936]

I have a very similar issue on our boat. I was unaware of the roll-over, so thank you for that! We have a Lowrance HDS5 mounted at the chart table using it's internal antenna. It takes about 10 minutes to acquire enough satellites to get going with positioning. It is older than the last rollover date. Is it an issue that the antenna is down below?


PS: I do not mean to hijack thread, but we both may have same problem, just a different perspective.

[Kerry1]

I had a similar problem with my Raystar antenna. The problem is now fixed because I bought a Vesper Cortex AIS which comes with it's own GPS antenna and now feeds that information to the Raymarine plotter and network. However as an exercise I pulled the Raystar antenna out and prized off the old battery which was spot welded in and fitted a battery and battery holder that just clips in for ease of replacement.

All this information is on prior threads on CF.