Slow boats - once or twice per day. Ranong - Koh Phayam 8.30Am ( 10Am) and 2 PM ( 3PM) . Boats leaving form two different piers - Koh Phayam pier and Tai Kak pier, 150-200 baht per person. Can bring own motorbike.
Speedboats: Several companies, from two place at Koh Phayam pier. 350 baht one way. From 7 Am to 4.30PM almost every one-two hours. You can book your ticket for boat or speedboat or even transfer from airport to island on the site below. Search tickets - Ranong - Koh Phayam