Thanks everyone for the additional comments. The white breast is always a challenge, because it is very white, and it gets reflections off the water to make it even brighter. If I expose strictly for the breast, even in fairly low light levels like here, the remainder of the image will be 2-3 stops underexposed, sometimes more. I am constantly changing my settings to try and hit the best compromise. Can't go just by blinkies on the histogram, because often it look good there, but the rest of the image (besides the whites) will be so dark as to be unusable. Just one of the joys of loon photography!
Ofer - at 1/320s, as in this picture, unless the loons are really in a hurry, I would say 60% of the shots are sharp, no visible motion induced blur. My little boat is a jon boat, which means perfectly flat bottom, it is fairly wide so more stable, I sit on the floor to lower my center of gravity, the camera is mounted on a pedestal, I have VR on, I work at long lens technique. Loons are very smooth swimmers, they really glide with little jerky motion generally, which helps too. I use an electric trolling motor, so very little vibration, if generally switch it off before shooting. Some days I am smoother than others
Cheers
Randy
Because of the problems with dynamic range I mentioned, you tend to shoot very early in AM and well into twilight, so I am almost always on the ragged edge of shutter speed.