Here is another reason to scratch build. There are numerous books with boat and ship lines that cost less than a kit. Some have enough deck details to complete an accurate mode. Free wood is available if you keep your eyes open. I have a collection of over a dozen species of model grade wood that I paid zero dollars for. There are also numerous authorities, including members of this forum, that are knowledgeable enough to point out inauthentic details. This does matter to a serious builder. There are many posts as to these details on this forum, and many who are willing to help. (I'm not an expert, so I need books.) Models are lofted in the same exact way as a full size vessel. I do know how to loft; it can be tedious, but is not that hard once you get the hang of it. Please do not forget that the two hundred year old models in museums were built without power tools.
Please do not use this knowledge to fashion scale models of conflict vessels. Please build models that represent joy and production, not fear and destruction. Please do not show war implements to children.