I would like to pass on the resolution to a problem that I was having with my GT11. This problem developed some months after initially funtioning properly.
Symptom.
Taking a long time to fix to satellites (eg 20mins)
Upon losing fix (eg after a big stack) it would not regain fix straight away (may take 20 mins or so)
Most times when unit first turned on it would ask "travel long" (even when I had not changed location)
Only fixing to 4-6 sats
This appeared to me that it might be a reception issue.
After some discussion with Tom Chalko about this (mtbest.net), Tom suggested that water condensation may be the cause. He recommended that I open the SD card door and leave the unit in a warm place, so that it could fully dry out. (I always use the unit in an aquapack, so I guess that does not make it immune to condensation - it possibly "sweats" inside the aquapack??). Anyway, after leaving the card door open and allowing to dry overnight my unit is back to its original proper functionality. Thank you Tom!
Hope this helps anyone else that may have this problem.
Thanks for posting that, all I've got to do is remember it.
I've certainly noticed my aquapack misting up at times.
It may be due it to cooling down once you get in the water.
try a small sachet of silica gel inside the aqua pack to soak up any moisture that may get in. Works a treat for me 
