Many of the sail boat trips (cat or monohull) have schedules which are incompatible with cruise schedules. Also, they hold more than 12, so you would either pay a premium to have the boat for your group or would need to share.

For 8-12, you might look at something like Sea More, Pirate's Penny or Stormy Petrel. You would get the whole boat and they would work with you on time and destination.