Sails?

I see HC members with HC patterned sails. I also see a MOTD on the Society in-game page that refers to sails. What is the mechanic for obtaining these sails, and what do they cost?

Bog

Sails and flags are submitted via user content http://burningsea.com/page/uc
As for the official HC flags, Jack, Émile, and I all have spares to hand out. Technically, they cost one doubloon a piece, but we are giving them out for free to members. We are so generous it kills us. I swear. Really, we are too nice. How will we ever stomach this cost...