Weird GPS problem
 

Well I hope this very astute forum can help me with my weird GPS problem. I have a Standard Horizon Chart 155C GPS. It came with the boat I bought last year so I assume same age as boat at 8 years old. Last year the GPS worked fine. When turned on it would typically pick up satellites within a minute regardless of the weather. This year has been totally different. If it is totally sunny out it takes a very long time, usually never to pick up the satellites. If it is partly sunny I can usually pick them up after several minutes. If it is completely cloudy out I pick them up as soon as I turn it on.

Tell me that ain't weird. Can anyone help with an answer.

easy answer- only boat on Cloudy days


:D:D:D

Total WAG's here...

Does it have a remote antenna?

If so, could the sun be heating it up a connection weakening it?

Do you deploy any shade from the sun or rain that has a metal frame effecting this?

The 155C does have an external antenna. Sounds like blockage or a poor connection, maybe corrosion. A poor connection may just allow for operation on a sunny day but clouds will add just enough attenuation to kill operation. So check the connections and use a little bit of dielectric grease on them.

The remote "smart antenna" requires good battery/ground connections as well as the antenna signal. Four connection pins on each end. Most likely problem is the ground.

Another WAG
 

This is also a WAG but I had an old Garmin handheld that did something like this. It had an internal battery that stored the GPS almanac when the 'main' batteries died.

After several years that internal battery died so every time I replaced the AAs in it I'd have to wait for it to rebuild the almanac. Garmin told me the almanac is basically a list of the GPS satellites the unit uses to figure out where it is.

I just Googled it and found this article that says it can take up to 12.5 minutes to get the unit working:

http://en.wikipedia.org/wiki/GPS_sig...gation_message

I Had this problem before with a Garmin. you need to hook it up to your computer and do a software update for is. A lot of times the Sats get repositioned or updated and the GPS needs to be as well. I did my update and everything worked better than before

I had the same unit on my Donzi.... had the same symptoms you did. Talked to Garmin, & sent it to them.. they did the software update (free) and sent it back... same issue...

Come to find out it the GPS needed a new antenna (mushroom shaped)... Cheaper to replace the GPS....


Woodsy

Thanks
 

It does have an external antenna, besides checking out the connections as you suggest maybe I will put a little umbrella over it.

It might be a thermal issue as mentioned above.

But it could also be humidity. Cloudy/more humid days without bright/hot sun might enable a connection.

If you would like to test it, I have the same unit in my boat and we could swap and see if the problem follows the plotter or stays with the antenna. If you need a firmware update, Standard Horizon will lend you a flash memory module that you put in the plotter so you can update it yourself.