Furuno GP32 -antenna under the deck?

[oldvarnish]

I've had one of these on two boats and have always liked using them. The most recent was installed a couple of years ago and the guy persuaded me that it was OK to glue the antenna to the underside of the deck, avoiding having to thread wires and making holes to get the cable through.
Most of the time this is fine. But recently, during my long Atlantic haul, I was unable to get a fix often for half an hour at a time. This doesn't matter much in mid-ocean, but it sets off endless alarms which are annoying. So I removed the antenna from under the deck and stuck it outside. It didn't seem to make much difference.
So I'm wondering if the antenna is going wobbly, or is it something to do with this:
http://www.furuno.co.jp/en/news/notice/20130214_001.html
(Has anyone ever heard of GPS rollover week? Sounds like something to do with the Lottery)

I also have a Raymarine plotter (A65) with its aerial also mounted under the deck. This is more reliable but this too sometimes has an outage.
Or perhaps there are more holes in the GPS coverage than we might think?

 

[Hoolie]

I don't have any experience of the two systems you cite, but I have a BU373 "puck" GPS mounted below that operates flawlessly. According to the GPS status display on the PC the signal level is not as good as it might be, but it works without signal outages. On the other hand our old Autohelm/Raytheon GPS with a pushpit mounted antenna occasionally loses lock.

Later technology of course, but maybe your kit is not that recent either. How can you tell???

 

[Ex-SolentBoy]

We had two Garmin GPS aerials. Both installed under the deck. Both never missed a beat.

Not sure this helps you, but I suspect loss of signal is nothing to do with the deck. GPS signals don't really mind GRP.

Wiring? Other materials? Aerial?

 

[mjcoon]

(Has anyone ever heard of GPS rollover week? Sounds like something to do with the Lottery)

Yes, but it does not involve any prizes; even if you "are in it" you don't "win it"!

The satellites transmit a simple date code which repeats, or rolls-over, every twenty years or so. So if the receiver forgets which twenty year "epoch" is the current one it can come up with the wrong date. (See paragraph #2 in the notice you cite.) My ancient 1997-era Garmin sometimes does this because its memory is getting as bad as mine... But I fixed it, for me, by writing a program which resets the date in the Garmin if that happens. But I didn't realise there was a recent roll-over; I thought it was months ago.

I very much doubt this has anything to do with the problem that you experienced; more probably it was a combination of poor signal reception and bad satellite geometry at the times in question.

Mike.

 

[geoid96]

The original GPS week rollover issue was back in August 1999. See:http://tycho.usno.navy.mil/gps_week.html

This Furuno one is a bit strange. It seems that some Furuno receivers are using a different week zero to the GPS itself. I don't think your issue is anything to do with week rolllover. Firstly because it's not yet Aug 2013 and secondly because the GP-32 is not included in Furuno's list of affected receivers.

Until about a month ago I had a GP-32 with it's antenna mounted under the deck. It worked fine. I have just replaced the GP-32 with a GP-33, currently using the same antenna in the same location. That also seems to be working OK.