Usually 7' to 8'. This concept was originated by Merve Larson, the father of wave ski surfing in America. Merve found that since you are sitting in the middle of a ski, you can't step back to the tail to turn like a regular surfer. So, he created a diamond looking outline that created a pivot point next to the seat. As you lean into a turn and bank up onto the rail, the tail frees up and the ski turns in a positive carve. This ski works great finless, but with one or three fins, you can eliminate side slipping with the fins just behind the seat, then do a powerful, crisp rail turn.
We also make this model with optional back rest for a disabled surfer.