Don't know if this helps,I have a GP32, presumably similar to GP35 and queried uploading with Furuno. The reply was that the GP32 needs to see a PFEC talker in front of the waypoint sentence, eg $PFEC, GPwpl etc etc. This is a bit Greek to me, but I got round it by finding a Furuno adapter programme on the Ozi-Explorer web-site, I sometimes use Ozi to create way-points. This it works fine for uploading.