Choose colours cobalt blue, raw sienna, burnt sienna and neutral tint (or paynes grey which has a little more blue) very small amount of burnt sienna + White gouache. Note the sand is black.

 rocky beach1    rocky beach2    rocky beach3

Sketch composition -Horizon line comes about 1/3 the way down the painting. Paint in the sky with cobalt blue add a tiny bit of madder if you want a slight purple cast.

Dry

 

 

Mix up mixture of blue + grey loosely from the horizon line down. Use dry brush to get the effect of sun on the water and the effect of spray on the waves

 

 

leave wave area white and add more blue going into dark grey as you get to the rocks. Dry

Paint the rocks roughly with a pale underwash using different colours and tones of blue, grey, raw and burnt sienna

 rocky beach4        
Use white gouache to paint on the white foam with a fine brush. Use a tooth brush to spray on gouache