I don't think theres any difference in the final knot - its how you tie it. Tying a figure of eight in the rope and then re-tracing it back is necessary because

I don't think theres any difference in the final knot - its how you tie it. Tying a figure of eight in the rope and then re-tracing it back is necessary because your harness loops (not shown in the pic) will be in the bight. I'm guessing a sailor wouldn't need to tie anything into the bight, so retracing wouldn't be necessary. I've never heard of a fig-eight being referred to as "trace" but this may be an US-ism and I'm European.