A pirate ship is read as rebellion and taking what you want outside the rules. Depending on whether you sail it or flee it, dream books see either a longing for adventure and freedom or a fear of something raiding what you value.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.