Update for yacht crew that do not have a Schengen Visa that are visiting Europe this year while onboard a yacht. The below rules only apply if you are signed onto the crew list of a yacht, (you cannot fly in).
General speaking if the crew is already on board there is no issue.
It depends on the country and sometimes even on different ports in the same country on how the immigration police would like to act in regards to issuing the passes or not.
For example in France, there is no need of shore passes, and the crew are allowed to remain within the port vicinity and if they want to go further they need to apply for the visa. Regarding Italy, during this specific period with all the restrictions in force due to Covid19, Yachts can arrive with crew onboard that do not have a Schengen visa but shore passes will be not released till the 3rd of June. In case the crew member (without Schengen Visa) would like to disembark we need to apply for a Transit Schengen Visa but we will need the Authorization from both Immigration and health Office (a lot of paper works but it will be possible).
In a normal situation instead a Shore pass will be released for all the crew members and they will be allowed to visit the City only in day light (till the sunset) but we have also some cases such as Venice port where crew can stay ashore till the 22:00hrs (as you see it depends on the port). As far as Spain is concerned, crew without a valid Schengen visa can arrive as crew, onboard a vessel, and continue to work and live onboard, however, they are restricted to staying within 10km of the vessel. No shore passes are issued. If the crew needs to disembark, an exit visa must be obtained for return to their home country. Greece: Corfu for example: Shore pass is possible. Visa is not a necessity if the crew is onboard declared on the crew list and is in possession of a seaman’s book. Shore passes can be issued at specific ports, not for the entire country of Greece. Please note that if the crew would like to repatriate then a transit visa will have to be issued prior to departure, same applies for incoming crew, visa must be issued outside of Schengen and prior to arriving to Greece
For any country that is not listed above you should contact your yacht agent if this also applies to the country you are traveling to.