How many Cobalt light frigates should it take to siege a pirate base in Sins of a Solar Empire

well put it this way its got to be alot...if just by themselves...the more of them there are the quicker they'lll destroy the cannons but with the other pirate ships i would recommend using more powerful ships Also it would be unwise to siege a pirate base early on since the defenses and the number would easily overwhelm even 60 cobalt light frigates, even more especially in a long term game where the pirate's ships could go to nearly 300 after 3 or more hours of gameplay.Do destroy such, I would recomment using the Advent's Capital Ship the Vengeance or the Mothership to destroy most of the ships with their special abilities accompanied with just a few powerful crusaders 20 in number fully upgraded will do. Using 3 or more guardians would be advisable since the sheer number of pirate ships could overwhelm your ships, and the shield advantage and push ability will give you the edge over the other ships. Or if you want to forgo all that, use the Vasari, build plenty of vasari superweapons, set them on autoattack on that planet. In maybe 10 mins, there would be nothing left but rubble and you could simply send in some planet bombardment ships and a colony ship and wala, the pirate planet is yours.