I had to google for what it meant in Portuguese. The Claw rig. THANK YOU...
Up until the end of the 1940's there were thousands of boats with crab rigs in the rivers of Portugal.
I love the looks of those rigs and if I am not mistaken, there are a few of them up north in the Aveiro River (where my boat was bilt by the way).
I sailed in one when I was 14, it was soo cool....I remember it so well.
These boats tended to be very very long and narrow beam, and the keel was a drop board that would be on either side. They were true work horses.
This type of rig was widely used by 1700's to 1900's for fishing downwind, and for cargo boats carrying salt and merchandise from boats moored off the Tagus river, in front of Lisbon.
I am searchin to see if I can show you some of these boats we had here with those sails.
Also..look here INTERESTING, but you wont understand a word...but some examples of what I spoke about.