Portuguese cannon weight in the Age of Sail

[sgtfox]

I've recently seen the armament for the Portuguese brig of war Gaivota do Mar. The tonnage, in English BM, is about 387 tons. That said, the guns given for 1791 are the following: 20-12#, 4-6#. Now, I've always used a formula of comparing the total weight of guns in CWT to the tonnage. The vast amount of warships conform to that. That said, twenty 12# guns would weigh about 600 cwt, while four 6# guns would add another 60 cwt to that equation. My question is, did the Portuguese use light guns like the Russians, Danes and Swedes? They fall somewhere between a long gun and a carronade for weight and range. If not, I can't see them staying afloat. I thought that the 12# might refer to carronades, but the Portuguese generally changed their 12# guns for 24# carronades at a later date.

[sgtfox]

Although it seems strange, I've found a few examples of the Royal Navy having over-gunned vessels. Thus, I'm going to assume that the armament of Gaivota do Mar was correct. Another Portuguese vessel, the Andorinha, was also first armed in a similar fashion, and she was close to the size of the brig. She later traded in her 12#s for 18# carronades, then, in 1807, for 24# carronades.