I fish a 6wt Rio Outbound short on my Predator and after a 3 or 4 trips, it started sinking too. I tried washing it with dishwashing liquid as the Rio Customer Service rep suggested but after about 15 minutes of fishing, it started to sink again. I called the guy back and he asked that I mail him the line and he sent me another one. It's the only one I've ever had a problem with and they corrected it.