Pattaya news says 15, which seem to include the sleeping capsules
"total of 15 rooms, categorized into 5 room types: Premier, Suite, First Class, Comfort, and Capsule"
https://thepattayanews.com/2022/09/11/the-blue-dolphin-ferry-successfully-launches-its-first-route-of-pattaya-samui-on-saturday/