I couldn't get ddp56 drawings to work right, so I don't know if they are what you need, but scale drawings are a big part of scratch building. Sometimes hunting for the drawings for a project you want to build can take longer than the building itself. However, there are lots of ship drawings out there- you just need to find them. Model ships used to be the genre of models most widely scratch-built, but scratch building has been dying off.
Once you get good scale drawings, you will find that not all dimensions you need will show up. Used to be almost every boy was taught some drafting in school, but those days are gone. So you may need to study up a bit on it. Good news is with CAD it gets pretty easy to do once you learn the basics.
There are two main ways to model ships- either hollow with interior structure duplicated, or the solid hull method, where you carve the hull from something and then build the superstructure. But you can combine the methods, making areas that do not have interesting interiors solid, and only duplicating the detailed construction of interesting areas.
Materials can be wood, plastic, metal, or even paper/cardboard.
Because scratchbuilding of ships used to be a popular hobby, there are a number of books on doing it. Good thing these days is that the internet makes finding old books easy. Many of these old books concentrate on building sailing ship models, but the same techniques can be used on building modern ships. You just do not need to put so much time into rigging.