Please refer to:
http://www.rathlinballycastleferry.com/
There are now 2 ferry services, a high speed MV St. Sorney boat taking about 20 minutes and the more tranquil car ferry which on occasion transports cars, people or even sheep from Ballycastle to Rathlin Island on a daily basis all year round. The journey takes about 45 minutes and has some of the most breath-taking views in the world.
MV Canna operating between Ballycastle and Rathlin Island