Thanks again, great info !
Raymarine has a firmware update and driver update so I just installed both
from the raymarine site :
Corrects an issue with STng bus recovery, after a brief bus power interruption
Conform to NEMA2000 specification changes for device class and function codes
Fix issue of USB communications
failing on some PC hosts when attached to the host while it boots
New config file to prevent conflicting GPS
data being transmitted onto STng (PGN129026)
After installing AIS works well on opencpn, I will leave it runnign and see if its stable now..fingers crossed!