Ripples in water are constantly moving, and our eye tends to focus on this shimmering and shifting rather than the underlying pattern. But freeze the action with a camera and it becomes easier to see. Sometimes the v's are pointy and sharp, sometimes very flat, and often a mixture. (Here are two reference photos you're free to use: gentle ripples and wider ripples.)
Various words are used to describe the pattern: inverted V's, flat U's, scallops, triangles, elongated zigzags. What word you use isn't important; what is important is that you remember that they need to touch (image 1) not be separate (image 2) and that the pattern is irregular.
This is a technique to practice in your painting sketchbook for a bit, rather than trying it for the first time on an actual painting. Start with a pencil and pen, working with lines only. Get a sense of how the pattern works before moving onto color. Draw the outline of a rectangle, a bit larger than you would for a thumbnail. Ultimately you'll practice this on a larger scale, but it's easier to start small. Draw a flattish zigzag line across the rectangle, near the top, then another below this that touches the first; repeat and repeat until you're at the bottom (image 1).
Do this at least a dozen times, as repetition is how it'll become instinctive. If you get bored with lines, divert yourself by painting in a row of the 'triangles' as dark tone plus some medium tone and some light. Ultimately you'll be able to paint in sea colors without the lines, but it's worth spending a little time mastering the underlying pattern first.
Remember, perspective applies to ripples, too. The 'triangles' get smaller and closer together the further away they are, towards the horizon.
Once you've got a sense of the underlying pattern in ripples, swap to a brush and do the same as what you were with the pencil or pen, but with thin brush strokes (image 4) instead. If you make a mess or it goes wrong, spread out the paint and then try again with some white (image 5).
If you find you tend to make each new line in your ripple pattern an echo of the previous (image 3), try breaking the rhythm up by adding single, individual ripples in between what you've done (image 4). Another 'trick' is to draw each line from a different direction, so one left to right and the next right to left.
Next step is to do it with paint without initial lines, and with different tones, so that ultimately there are no white gaps. It's easiest if you start by painting the whole rectangle a mid-tone, then adding 'triangles' in a dark and a few light tones (image 6).
This technique is merely a starting point in painting realistic ocean ripples. You'll find you expand and develop it as you use it, for instance by using a rigger brush.
A rigger brush is perfect for painting ripples as it gives you a long line without stopping to load the brush. The key to painting a lovely clean line with a rigger is to pull the brush, not to try to push it.
The line is created as you slide the brush along the surface, not by pushing the paint into the surface. To get a wider line, lower the bristles so more than only the point is touching. To vary the width of the line further, turn the brush between your fingers so it rolls a little way across the surface. To narrow the line again, lift the brush as you're pulling it until only the tip is touching.