Went to the artrage site:
ArtRage makes it easy to recreate photos or other images using its paint tools. When you load a Tracing Image the original is projected on to your canvas so that you can use it as a guide while you sketch and paint.
Couldn't you just draw a smooth coast then using the quoted feature, trace over it "squiggly" with a fine brush?

That is how I do it by hand with tracing paper....

-Rob A>