They are spacers between the inwale and the hull planking (shearstrake). In traditional boat building there would be frames running up the hull. Spacers were added between frames filling the gaps in a uniform pattern. The inwale added structural stiffness to the hull. It does look good. The benefit of the doubled outer rail in the skerry gives you a smooth surface to lean against when sailing. Alot of builders make modifications, customizing the boat to their liking / needs.

I did notice that the oarlocks were located on the outer rail. Don't know if it makes any difference. I have to figure out how to add a picture one of these days when I'm not building.

Not only does it look good to have the spacers between the inwale and the shearstrake, it also has the advantage of providing numerous places to tie-off light lines tied to things like a bailing bucket or any other object that you wish to keep in the boat in an event of a capsize.

Another advantage is that when you are cleaning out the boat, you can tip it up on its side and the water will run out through the spaces between the blocks.

On the 'down-side', it does add time to the build and especially to finish and maintenance. Painting or varnishing between the spacers could be difficult.

The next boat will have an inwale with spacers for just that reason. I put holes in the frames to tie stuff. The boat is almost ready for the water. 

Your Skerry looks great. I go back and forth on nright finish vs. the durability of paint. I was moving towards the popular white/bright configuration - white hull with brightwork inside. The gentleman from Alaska had his seats bright with a nice painted finish on the inner hull - that was attractive fo rmaintenance and with the kids/pirates running around. But I was unsure if it would satisfy me as the builder. Your approach might be just what I need.