Basically ships like that have multiple layers of thick cured planking. The very first thing that was placed was the keel, ribs, masts. The main frame of the ship to get the shape and form down. Then they built the inner hull, a layer or more armor plating which was more wooden planking or even plywood. And then the final outer hull was put on along with the sails and other bits. All of it was waterproofed with cotton, hemp or other types of fiber robes soaked in tar, asphalt or creosote at each point. All of this was of course held together with tar or strong glues and heavy iron riveting or nails. Of course the thickest planking was built along the upper waterline based on how low the ship might sit and downward to warp around the bottom to the keel. Long, hard, strenuous process to build a warship like that. HMS Victory took them about six years or so before it was even launched and placed into service. Waterproofing was one of the more painful tasks since they had to mess around in tar and other goop and twist up lots of rope to cram between plank edges.