I still feel like the proportions are a bit off. First of all, the foremast is way too short, second, ships of this era were tall and thin, yours is too broad in my opinion. Also, the increasing levels on the stern end should be sloping upwards. You should accenturate the angle of the stern and the aft galleries, in games, and low poly models in particular, lifting out theese notable features will make the ship feel more genuine. Finally, i think you can afford to add another segement to the forecastle and make the front of it square and then lowered, as you can see
here, not to mention add the little piece of prow that supports the foremast (the one that the figurehead sits on).
Another important hint i should give you, that will not increase filesize, is to make the filter mode of the material of the ratlines blend instead of transparent, this will cause them to render at longer distances, and remove that sharp, paper-like feel they have.
Now, i know it is not in any way fair to compare a 1800 poly ship with a 10000 poly one, but if we compare the silhouettes of my fourth rate model and your ship, perhaps you will understand what i mean:
And here is how i meant you should do the aft, with just a few extra polies: