Just for reference, here is my setup which also works:
PC: Thinkpad T440 running Win10 pro
Gps-dongle: Globalsat ND100-S, some years old
GPS-testprogram: GPSinfo, GPSInfo for Windows
(Supports Windows 10, 8, 7, Vista,XP)
The GPS-dongle is found in Device Manager as COM7, it uses a Prolific driver dated 04-09-2015, version 22.214.171.1247.
I set the port to use 4800 baud.
Works fine in OpenCpn, but only one program (i.e. either OpenCpn or GPSinfo) can be running at one time