Eddie did a quilt called Surf Song and quilted along each color diagonally from corner to corner. Here's a link. It looks great!
http://www.quiltingboard.com/picture...22-t35462.html
Depending on the style of the pattern, you may be able to use a walking foot to do the same type of pattern.
As for FMQ, google clip art of ocean waves and print something out. Or you could freehand some C shaped waves in rows. There are a few ways to handle that once you pick a pattern. You could mark the quilt directly; you could trace it onto Golden Threads paper and follow the lines, quilting right thru the paper or you could trace the design onto Sulky Solvy and quilt directly thru that. I never draw directly on the quilt myself. The only time I did that was to draw the scallops on a border, but I was cutting on the line, not quilting. I'd rather not take the time to remove my markings after.
The Golden Threads paper is great because you can draw it once, stack them up and sew on the lines without thread, then you separate the papers, and quilt each one where you want it. It is translucent, so you can usually see where you are going with the paper on. The only drawback to this is removing the paper after. I still have areas where my stitches are small and it's harder to get the little bits out. So it's quicker up front, but takes a little longer at the end.
Some people use the Glad Press & Seal, but for me, I find it's a pain to move the little bits leftover in the tight areas.
The Sulky Solvy is kind of like glad wrap, only it is water soluble. It's easy to see where you are sewing because it is clear. I draw the designs (need 1 for each block or section), sew thru them, tear off the larger bits and the rest washes out when I wash the quilt after binding. It's more prep work up front, but a breeze at the end.
I draw my designs with Crayola Washable Markers. I use them because I've tried other markers on sample sandwiches and had a hard time removing what transferred onto the thread when I sewed.
I choose my method based on the particular quilt. If I have a lot of repeating blocks, the Golden Threads is easier to get consistent designs done. If I need to be more precise as to where I am stitching, I use the Sulky Solvy and can easily see if I need to adjust a little to get closer to the edges of the pieces, etc.