routing around an island

OK, found your starting point on Internet it is not 52°N but 54°

So I would proceed the following way (there are other ways of course).

I will first create a small barrier inside the island, just in the land, will be used later. I will also create a POI call "finish" at the start position, since we are supposed to come back there.
 
Then I place a point somewhere behind the island, and create a routing.I do NOT convert it into a route.

Then I move one point of the barrier in order to block the return from where it comes from (i.e. to force it to round the island), I click on the last isochron, choose an isopoint, right click on it and ask "Edit pivot".
 
When editing the pivot I change the destination to "Finish"
 
When the routing is completed I do NOT convert it to route immediately. I first replace the barrier inside the island so I will not interfere with the simplification/optimisation process. Then I edit the routing and convert it to a route (asking to delete all other routings in order not to keep the parent routing). I optimize/simplify and finally arrive to this result:
 
The POI in red is the pivot point, and is not simplifiable. Depending on the case I would either delete it or make it simplifiable, here I choose to remove it since we have already many points behind the island. Then I zoom on the island, select a zone containing all POIs behind it, right click on the route and optimize.
 
After the optimization I clear the zone selection and run again optimization on the full route this time, and I get what is probably the best possible passage around this island, in this case close to it but it could have been the opposite. The optimization process would have catch it if there is better wind far from the island. Here is the final result:
 

Of course then I will try to force the program to choose the other side for rounding the island, following the same process but with a different first POI.

I will of course display the grib and replay the route to understand why the routing made these choices and to try to identify key points in the grib.

And then I will load a vector chart here and choose "coast line by vector" to see if there are other dangers on the route.

cool. thanks a lot. i will try to understand your method.