Well, in international law, unless they forbid the ship from entering their waters, it may legally do so. If it enters after being refused, it has committed and act of piracy.
But I estimate that they will stay in international waters.
territorial sea: 12 nm
contiguous zone: 24 nm
What this bunch does is sail around to countries that don’t have abortion or where it is illegal, picks the women up at the dock then sails out to “neutral waters” to preform the abortions. That way no laws are broken in that country.