Mike, I made the changes you have suggested (more on that later),
compiled weather_routing_pi, compiled a fresh grib_pi for release,
placed in a release version of Opencpn 3.3.1117.
Then downloaded a fresh 16 day wind
grib from saildocs and opened it with grib_pi.
Then opened Climatology, set it to December and checked Wind
Then opened weather_routing_pi, made a new long route
by right clicking and selecting "weather route position" and creating two weather
route positions new-start2 and new-end2.
Then created a new routing (configuration > new).
Then double clicked on the new route to Edit. In there checked grib, climatology, avoid land, and currents. Set max diverted course to 80. Set the End and Start to the Weather
route positions. Clicked on "Grib Time". Hit "Generate" to regenerate the steps. Set time step to 6 hours. Then went into Boat "Edit" set Boat values in Statistics and Hull
tabs. Then went to Plot Details tab and hit "Save", the Boat settings close automatically. Then Close "Configuration".
Now hit "Start" to start making isochrones and an optimized route.
See attached result. 24 days (16 days of grib, rest with climatology)
For some reason my older gribs would not work, the routing failed. It took a number of tries to get it going properly, but it works now in Opencpn 3.3.1117.