Perhaps you already know this one:
http://www.histarmar.com.arA website about the ships of the Argentinian armada, with lots of photographs and very often drawings as well, and their histories in spanish.
But the bonus is in the details: there are photographs about other s-american navies as well, including a delicious set of visiting ships (mostly naval) in the harbour of Rio de Janeiro between 1880 and 1900.
Another set has an immense amount of photographs of wrecks, hulks, and decommissioned rustbuckets all around Argentinian ports and beaches, each with some background information and close-up shots.