If I'm not mistaken the F means the forward part of the ship and helps the persons responsible for your luggage get it to your cabin as quick as possible.
🚢 Cruise with your favorite Keene Luxury Travel Staff Member! 💰 5% KLT Reward plus Shipboard Credit available (amount varies per voyage)! 💲 Offering Enhanced KLT Rewards on voyages hosted by Ngaire & Clay!