Setting up a pirate themed room next year in our towns big haunted house. Attached is a 10 minute .mp3 link that I will have playing in a loop. I made it myself and you are welcome to use it.
A suggestion for your pirate themed soundtrack, especially if you're going to have folks playing the parts of pirates in the display. Add more music, at least another hour. Your guests won't mind, because more than likely they're going to be in and out in under that ten minute track. But for anyone staying the night to help out the haunt, ten minutes looping will wear a bit thin even with great music. Giving those folks something to listen to that doesn't repeat every ten minutes will make the evening less repetitive, and that's a good thing.
From one who has worked a few jobs that had looped music, I can attest to the idea that more is better. Just think about all those times you've been placed on hold for extended periods of time with a company that uses one song as their hold music. If you type in "Pirate Music" on YouTube, you will find many tracks that include hours of swashbuckling music. The town would have to look into fair use laws or royalty free music, but for the sanity of those participating it might be a worthwhile kindness.