Surfing Waves

ive used a single fin all my life and now i have a 10ft board with a 2x1 fin set up. any suggestion what size center fin i should use. thanks.

You could try the 9.5 "Turbo Fin" with the side bites on and all the way forward in the slot. You can go down to a 9" cutaway with the side bits on. Take the side bites off for the smaller mushy waves to cut down on the drag. Its all about experimenting and getting to know the new board. I always have a screwdriver and hex key with me to change the setup depending on the conditions. (Gives me something to blame on a bad day)