16 Crosstrek Premium Quartz Blue Pearl
Yes, it was the wind, but nothing to do with an anchor. Here's the full story.
Flew into a remote alpine lake with glacier melt water (ie ice cold). When we were ready to leave, I left my plane sitting on the sand bar (after positioning it for a quick go) for a few minutes to help push a friend off in his plane. Meanwhile the wind caught mine and took it off the sand bar. I had a pax inside but he was not a pilot, so no help there. I first tried to swim after it, but couldn't catch it. The wind was sweeping it along the shore toward a point, so I waded along the shoreline as fast as I could toward that point. There I swam out to catch it as it was going by. It took all my might and stamina, but I caught it, just barely. By that time, I was so tired, and cold, that I had trouble climbing up on the float out of the water. Again, it took all my remaining strength, but I made it and into my plane. I promptly got it started and kept it away from the rocky shoreline. If I wouldn't have caught it there, might have been a very bad ending, at least for my plane. After it was going, that's when I really noticed how cold I was. My feet were totally numb, and had trouble working the rudder pedals at first, as they felt like blocks of wood. And I was shaking like crazy, took me about 15 min to stop,.. as I was flying. At least it was a hot day out, and I was able to warm up pretty fast.
I often take vids with my plane (3 vid cams mounted outside), and here is the actual youtube of this trip.
Maybe you need a bigger float plane.