I am struggling with the focus on the water at the moment. Today I used the Canon GX7 at f5.6 with its longer zoom lens than the Sony to get closer to the reflections rather than sitting on top of them. The result - The close up is generally blurred like the depth of field. There are occasional shots with some degree of sharpness in the centre of the frame. However, generally, I did not find photo serendipity to-day.
The autofocus takes too much time to set properly before shooting when I am moving. I am travelling between 1 or 1.5kms as I approach the image so there is quite deliberate movement required to approach the reflection. Stopping is not an option as using the paddle to stop creates ripples and generally disturbs the water surface. Focusing the camera manually in this situation is just too complicated.
This review http://www.cnet.com/au/products/canon-powershot-g7-x/ confirms my suspicions that the Canon G7X has problems in all the areas in which I am experiencing difficulties
So I have now adjusted the aperture to f/8, turned on the continuous autofocus and will see what happens on the next kayak..