In look at the water in this painting, one feature to note is the side lighting of the waves. With light coming from the side, there is a special sparkle to the wave crests, and the troughs are darker in colour.
An interesting feature to note is a detail to be seen in the sails of the schooner. You may have noticed in paintings of old sailing ships that there are little pieces of rope secured in the sails along reinforcing ribs at an equal distance from the boom. These little ropes are called "reefing points" and are used for "reefing" the sails.
"Reefing" sails was a way to take in some canvas when high winds would put too much strain on the the sails. With the upper boom lowered slightly, canvas was gathered in and the reefing points on either side of the sail would be tied around the lower boom, and secured with a "reef knot" (also called a "square knot"). With the reef points secured all along the boom, the sail would present less area to the strong wind, which in turn put less strain on the ship's rigging. You will notice that one of these sails has two sets of reefing points. If sail is taken all the way to the second set of reefing points, the sail would be "double reefed".