The Black Sea in winter can be a hard place to be. Back during the "Cold War" I discovered this when as an USAF communications
tech I was assigned to a SAR (Search and Rescue) aboard a Turkish Destroyer (WWII vintage) when a RB-57 went missing on some undisclosed mission. Was suppose to be a 4 day activity which turned into 14 days. After the 3rd day our bring along food
ran out and we started eating the echmec bread, garlic and Chi... a hot and very sweet tea. Not sure if it was the weather/ seas or the new food
but I was sick as a dog for the remaining 11 days and spent 5 days in the hospital when I got off the boat
to get my fluids up to where I could walk again.
I lived and worked in the area between Istanbul
and Synop which is on the Black Sea for more than a year and in general the commercial
boats are typically in very poor condition... if not for pumps screaming at near full power... I suspect most would sink to the bottom even if tied up to a mooring
in good weather
Have never considered sailing in the area in winter.. BUT the area around the Dardanelles and Princes Islands would be a treat in the summer.