In Crimea there are not many suitable harbours or Marinas
for that matter. Cruising sailboats are relatively non existent as are resources for them. There are the bays and inlets in Sevastapol but most all the harbour is reserved for the Russian Black Sea fleet. Mostly aging hulks. But being renewed with new frigates and submarines in coming years. The is Balaklava harbor has a few small marinas
without any amenities. This is the harbor that contains the recently revealed secret Russian underground submarine lair built into side of mountain. The famous resort town has a small seawall harbour with mostly a few sailboats trying to lure Russian tourists to take day cruises or hourly cruises ( mostly all without sail ). There is a small shipyard there with railway, but the hard is cluttered with tugs and ferry
boats. No real room for hauling for repairs
. Various other towns along southern coast such as Sudak, Koktebel, Feodosia and Alushta and others have piers for ferrry services only, but no real sheltered harbours to speak of. The sea bed
is rocky everywhere along southern coast of Crimea. Winter usually has horrific gales coming off sea from the Caucasuses and Turkey
. Even in summer the number of afternoon gale days are high. Especially around the Sevastapol point.
It is not a hospitable sea in winter. In fact it was originally called the inhospitable sea in ancient times. As merchant trading started to increase the name was changed to hositable to promote trading. Eventually the name was changed to Black Sea as it has huge lower anoxic layer of water
in lower depths. So not much lives in lower black depths.
As far as transient entry, I can not tell you as I have yet to see any yachts arrive from outside of Black Sea area. Freighters yes. Yachts no. But if you come prepared for lack of services, you will find the Black sea pretty much all to yourself. Most normal Ukrainians and Russians can not afford yachts for recreation so the area is still wide open for opening such services for transients. And the seas empty other than naval vessels and freighters or the occasional jet ski.