It would be best to do your research based on ship type.
For instance if you wanted to find information, prints, etc. on Drakkars, then look up that type of ship.
If Caravals, then look up Caravals, etc.
Or, look up by nation of origin, design, or fleet usage.
You're probably gonna have luck at your local library if you know exactly what type of ships you're gunning for.
One thing I've done is research deckplans and construction methods and then deisgned my own ships using real/historical ships as templates, but adding or subtracting various design elements based on the technical and engineering and shipwrighting capabilities of fictional game navies. That way you can create ships, boats, and other craft to your own design specs.