Realizing that it is thread-drift, I've never understood this fascination with Flemish coils, in models or in real-life.
I realize that Flemish coils are much enshrined on models of all sorts, but they are finicky beasts at the best of times. But, they are not the sort of thing a person would ever leave on an exposed foredeck while underway. That, and they area terrible way to stow line for immediate use, too--a proper salt "flakes" line out to run, if such is needed. Flaked lines can be snubbed with "small stuff" to keep them corralled before need, too--the sort of thing any Bo's'un worth his Crow learns early on.
A person operating small craft learns that you might not "need" 7:1 scope for an anchor line, but, 5:1 is still a lot of rode to stow out on deck (15' [2m] anchorage wants 225' [±70m] of anchor line. In case that number does not mean so much, it's three times the length of an 80' patrol boat--and that, before leaving some "extra" to tie off the other end of the rode,as small craft lie better to longer scope than their heavier brethren. .
A flemish coil is very neat and tidy, and looks very nautical and takes up bare bits of deck--all of which why such are beloved of less-salty model builders and officers of a white-washed rock frame of mind.
That being said, and the thread owing some focus, put out some double-stick tape, or tape some 3m painter's masking tape sticky-side-up on the bench. Make up the coil, letting the stick-um help you out. When you get the desired diameter, give it a spray of spray fixative, and flip that onto the deck where needed. The tape lets you handle this neatly (good for pressing over deck details, like the bitter end of the line going back to its locker). Once stuck on, the tape can be gently removed, and a shot of Dullcoat will (ought) hold it in place.