I found a light colored and light weight old dress shirt that was too small and got a large pair of scissors. I just made four cuts in the shirt. I cut each sleeve, the collar, and the bottom.
Here it is in action. Next, I need some pirate pants next to protect my knees. Cutting an old pair of light colored pants or white light weight sweat pants right at mid calf would work great.
This all made me think that maybe those pirates made their clothes tattered at the ends on purpose?! The cuffs of normal shirts and pants could get caught in ropes easily and are not good when swimming, but tee shirts and shorts don't protect elbows and knees from the sun.
I sniffed around a bit. According to Cindy Vallar, on her The History of Maritime Piracy, Pirates and Privateers site, it's somewhat true about short hems, and they liked tight clothes to keep out of ropes, but also lots of lowly crew just had old clothing.