Exactly. One way to improve your drawings, though, is to draw a unique underwater hull for each one instead of doing Copy, Paste, Resize. That will go a long way to improving your ships. But first start with some real designs, scrounge around on TheBlueprints for a good line drawing, then check the archive, Real dsigns forum, and Worklist Registry to see if it has been done. If not, have at it.
When you think you're ready for an AU, start with a concept. The easyest way is to start with a historical event (not something like World War 1 or 2) and say, "what would have happened if this event had turned out differently?" Golly's Byzantium/Komneturn, Redhorse's Republic of Texas, and barnest2's East India Company are all great examples. When you have a concept going, try to figure out the veiws of your Admiralty. Are they stingy and ornery old men who prefer that things stay the same, or are they more moderate, or, are they idealitic and seek out each new concept with high interest? Once this has been set out it is time for deciding how many ports and shipyards your nation has. This decides not only the size of your navy, but the scale. If you have say, 5 harbors, each with a depth of around 15 feet, that will mean that you can't have super huge ships. Being able to say "This is the Name I made up on the spot Class destroyer, which wa laid down in City Name ship builders in 1942" adds great realism to an AU. Also, try not to go for a world-influencing-first-rate-navy, these tend to be less interesting and get old after a while. A good second or third rate navy will be more interesting and enjoyable, as such navies don't have the assets of a first rate one, and thusly have to compensate. This leads to interesting hybrids and smaller vessels, which in turn, make an AU interesting. Trust me, it is much easier to do this ahead of time and then try to fit it to your ships.
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"If people never did silly things nothing intelligent would ever get done." ~Ludwig Wittgenstein