[Alpha Von Burg]

From what I know the big buoys have flashing lights on it, color of these lights can vary. This was normal so as to prevent ships from colliding with them at night, whether they were nets or not, which were usually on the ends of nets, or mid-sections. The smaller buoys holding the net were not given lights as the larger buoys at the ends would naturally act as markers.

Historically, ships were normally given charts as to the proper course needed to navigate around these buoys, nets or even in some occasions, mines.

For ships without these charts, escorts were assigned.

Anyway, hope this helps on a historical note.

Cheers,