Re: OpenCPN to Garmin
Yes, I've done it with a Garmin echoMAP 54cv and a Garmin GPSMAP 400/500 series. Garmin has two file formats for routes, GPX and ADM. Be sure you select the GPX format when you want to see files from OpenCPN.
1 Select Nav Info > User Data > Data Transfer > File Type.
2 Select GPX.