I just measured my Constitution mainmast lower yard and studding booms (placed INSIDE - no sails) and got 15 3/16". I'm almost done. Need braces, cutter, jollyboats, and sailors. I would imagine that the studding booms on the mainmast lower yard if placed on the outside for sails would add another 4" total width +/-. I hope this is helpful.
Mike Stolting