Most Ships in what we would probably think of as typical ‘pirate period’ didn't really have “bathrooms” as we would think of today. instead, ships just had the head of a ship, which functioned like a restroom but looked very different, and notably did not afford anyone any privacy.

 •So just take a moment to consider: Bladder shy pirate/sailor omo. Whether this has been an issue for a while they’ve managed to deal with until a certain point, orr it's someone new to staying on the boat. Of course, it doesn't help to be surrounded by miles and miles of water on every side, or if it's a small ship and privacy is already a laughable concept as is. All in all, I just feel like that would be the perfect storm and speaking of stormss

•Storms: Already an INCREDIBLY dangerous thing at sea, even today. a good amount of work on the crews part in dealing with/ surviving them, and definitely no time to take a break to go piss, even in the unlikely scenario that doing so would even be safe! It wouldn't really matter if they couldn't hold it, though, would it? They are already plenty soaked as is, nobody could tell, right? Least aside from anyone who knows their tells particularly well. 

•I'll also say, of course you could just piss off the side of the boat: definitely not just anywhere though, If you're facing the wrong direction (towards the wind) that would surely lead to something unfortunate. Of course, that'd be such a rookie mistake to make. Who would be so silly! Maybe it's a little easier to screw up in that respect when you're already desperate and not really thinking, yaknow? 

•Depending on the setting and time period, it might not be unlikely to assume they might not have more than one set of clothing. This also makes wetting much more inconvenient and leaves you kinda stuck in a sucky situation even after a while after the fact for one reason or another. 

me realizing that Ben Fucking Linus in his kid form is the Primordial Sandwich Giver (to the Imprisoned ManTM): OH MY GOD. OH MY FUCKING GOOOOD. OOOOH SHIIIIIT. I need to start over, this is INSANE, WHY WOULD THEY DO THIS TO ME, OH MY GOD.