PotBS - Dev Journal @ Official Site
A new developer journal at the official Pirates of the Burning Sea site takes a closer look at ships of the line.
From the start, our goals have been for SOLs to be very rare, very hard to earn, and to be deployed only at port battles of great strategic importance to a nation. We havent met these goals very well. In the closed beta, SOLs were earned by getting a Writ, and the most efficient way to get a Writ was by mindlessly grinding high-level NPCs. Since grinding would get you an SOL, they were seen frequently at port battles where they utterly dominated. This meant that getting an SOL was a sucky single-player grind and that many players got them and used them in every battle they could.
Source: Flying Lab Software