Donny,
Are you going to use your Mackie's on the cruise?
Up until I got the Bose L1, the captain of a similar cruise to yours told me all speakers had to be on the floor. No pole mounts.
Even with the Bose, I can only use one section of the L1 due to ceiling height limitations in the salon where they wanted the music.
They have also called about me playing outside on the upper deck...but I won't subject any of my gear to the salty air..even under cover.
Eddie