Yes water is a challenge, however, I have been blessed with finally figuring it out, at least my interpretations. I have several books that really helped me find a method of drawing clouds and water along with shading using pen and ink.
One book in particular is by: Clarence P. Hornung, i.e., "The Way it was in the USA, New England", pages 24 and 25. This and two other similar titled books are a compilation of old engravings. Very nice work in these books produced by some of this countries greatest documentary artists whose work was widely disseminated in newpapers and magazines.
I have all three of Hornungs books and they are very inspirational.
Good luck with your work.