Is it Hard!
Nah! First you have to know what kind of ship you want to build. Now I will say that I have NOT chosen to do small scale war ships this way. I am sure I could, but I have chosen to concentrate on Civilian vessels from Tugs all the way to Liners.
Next is acquisition of some parts. Are you going to do a Tanker say, or a Dry cargo ship. Dry Cargo can be anything from taconite, in a class of ship known as a Laker. Or are You wanting to build the Ocean-Going variety that ply the oceans mainly. These are referred to as Salties in the Great Lakes and Northeasterns Inland waterways.
You must have Plastic. I use.030 and .040 for the Deck and Base plates and ProfilePlate. When you do the next step you will lay out the plates according to their place on the ship. An outer profile drawn to a centerline will work for the deck and base plates. The baseplate will reflect the shape of the hull where it enters the water. The deck plate wil also have slots in it to allow the upperworks(Deckhouse etc.) to come through. The Bottom plate is a butt joint along the centerline with the profile plate held vertical. You can plate the hull with .010 or .020. This way you will have scale thickness on your bulwarks. This works in the larger scales of 1/96, 1/87, and 1/100as well as 1/200 also the scales of 1/400 and down.
The easiest way is to build the hull like you would build a Paper or Card ship model. First you create a profile that goes from the Boot stripe to the Funnel tops(If it has them) Then you create a Bottom plate(The part in contact and visible at the water. Then a Deck-Plate (Deck). Take the profile plate and create slots in the deck plate( to allow the profile plate to slide up into and mesh nicely with the deck).
Then making sure that those are true and square, glue them together. Find the centerline on the base Plate. Then glue the profile plate to it, again making sure it is true and square, Letting this assembly dry for at least a day. I find with most plastics this works best. Plate with the thinner stuff and if your ship has a very flared bow or stern, do those in diagonal strips so you can shape them right. This works better in plastic for sure. Happy Building! NOTE: Please don't ask about older Galleon style sailing ships or Ships of the Line. They are too difficult for the casual builder and very tricky to boot!