Seem seems like the right spelling for seam, but it seems to be seam is the right way...so it seems. See what I mean or is it meen???
Seams in the hammock are usually parallel w/ the rl. Some folks have done seams perp., but best to avoid them. Lots of stress on the fabric and stitches. Parallel spreads them out more. Many manufactured hammocks do the perp. seam.
French seam comes in a variety of styles and techniques.
Mock french, folded french, modified french, kissing french..oh wait thats another forum.
Heres a thread from a while back check the images in this post for a clearer example.