I just want to add, taht winzip is an awesome mod tool that saves a ton of time. Say for example you need to make changes to the SNS file of every ship in the /data/sea directory.
Instead of creating all those directories, and copy the file over, just winzip the ENTIRE sea directory. Then open this rather large zip file, sort it by file type, and delete all the file types you dont want in your mod. (in my example id delete everything but the SNS files) What your left with, is a zip file containing the just the SNS files, and their directory path information, ready to be unzipped into your mod. The entire process takes like 2 minutes to complete.