Not good current advice for a potential bareboat charterer regarding sailing to St. Barths from SXM.

You CANNOT go ashore until certain requirements are fulfilled, such as:
(for boats arriving from neighboring islands):

"everyone on board must arrive with a negative rt-PCR test done less than 72 hours prior to the vessel's arrival."

see biosecurity section of link:
https://www.noonsite.com/place/st-barts/formalities/#biosecurity-section