I have and have used both skills (Take Cover, and Open Fire), I didnt get the "Open Fire" skill on my first pirate, and made sure to get it on the next two, I have noticed it make a broadside from my ship do up to 2x more damage than normal. Its recharge rate, and short usage time however makes it a one time per battle option. Looking for skills that make some major noticeable change, and these arent what your looking for. Winning battles isnt all shock and awe.... sometimes the subtle things make all the difference.
Zeppers Lvl40
http://pirates.teamofx.us