Blockades - what is counted?

[Rafiki]

The tooltip for blockading says that "you need at least X naval combat units to blockade this zone", but what actually constitutes a naval combat unit? I'm guessing that it needs to have at least one element with a positive offensive rating, but do the number and types of elements have any say at all? If not, brigs seem to be the best (as in, most blockading power compared to investment) blockade ship at sea, especially since they are good at evading anyone who might come along to break the blockade?

[Pocus]

for now, things are simple. As you say, any unit with an offensive rating will do.

[Rafiki]

Thanks for the clarification, Pocus

[marecone]

I will double check in few hours but I am pretty sure that brigs don't blockade. Also, as Rafiki said in grand campaign project (which looks soooo amazing and feels like reading a book on actual war but with more pics and flavor ) it seems that game counts units and not elements for blockade. This is unfair to the blockade squadron, as he said.
This seems like an area worth investigating. Plus if something could be done here with auto stuff , that would be great
Just my two cents