Well, call me stupid. I have never thought of adding detergent. That's a great idea. I'll have to do that for my tarps. I keep messing them up because of their size....
Anyway, I was thinking about the torn sail look. There are several ways to approach this. First, is if you want a "reason" for the tears. Some questions you would ask yourself would be; Do I want some tears to be from ancient cannon fire? Over time, how would a sail actually tear and detiorate? Just a couple of questions to ask yourself if you're going for a certain look.
Now, as I understand, you're using the plastic sails as a template. Okay, I agree, the detergent will be a great way to work it. Your sail should just slide right off the plastic.
Now, as for tearing too much, you could try a couple of ways and see what works best. First, sumpter is right, for larger tears, say, along the trailing edge of the sail, where tears seem most logical, you could "precut" varying sizes of triangles. Then, lay the sail in the template and wet it down. Once it's soaked, take a pair of tweezers and gently pull on the ends, causing them to tear a bit. Do this just enough to get rid of the clean cut you originally made.
Now, as for holes IN the sails, do the same thing. Make a small hole in the paper/tissue your using before you lay it in the template. Anything could work. Perhaps just cutting a small round hole with a very sharp knife. Put it in the template and wet it down. Then, use the tweezers or a knife to pull from the top of the hole you made. Do this gently though, because you only want to fray the edges of the hole. For the bottom edge of the hole/tear, you might want to cut into it a bit so that there is a little excess sail hanging down, like its been torn from the top.
There's a lot of room for innovation here. I'm really intrigued by the idea of modelling the Pearl, or, a ghost ship in general. Whatever technique you use, I can't wait to see your photos.
Here's a question for you, how do you intend to do the rigging? I imagine, on the Pearl, the lines were not in the best of shape, perhaps dirty, some actually torn/cut, and just dangling from a yard, or from a stay.
Man, the more I talk about this, the more I'm getting the itch to just do it. But with 3 different kits waiting in the wings, and my son's 1/96 Cutty Sark sitting on my workbench, my wife would kill me if I picked up something else.....
Keep the pics coming. It's looking great.