So I'm in part six right now and I just got to rivet city and I'm trying to get into that airplane carrier, but I dont have a lockpick of 100. How am i supposed to get in there? I'm totally stumped.

There's an underwater entrance. I go to the top of Rivet City where the planes are and facing the Broken Bow, make a save and then jump off the right front edge of the ship. Turning on your Pipboy light will help you find your way to the entrance. Be ready for a fight when you surface inside the ship.

Edit: Wait, I'm confused by what you mean by "part six". Unless you're looking for Pinkerton, there's no need to get through that 100 lockpick door. To get into the rest of Rivet City, you only need to go up the ramps by the Rivet City sign and activate the intercom for the bridge to be extended.

I grant you it's perhaps possible to get in that way, but I drowned so many times trying to do it that I found it to be much easier to wait until I had lockpick 100. :brokencomputer: