first the math. 

take you damage vs number of cannons, and do damage / reload time = your dps.

Just a few TIER IX ships for show how nerfed bb and ca is now..

Note: I used USA CL, cause IJN (my lane) is based on torps only and dont have cannons like other nations and its the just one big nerfed (torp damage -30%).

NAGATO (BB)
   49.576 every 14,39 sec (my time)

   49576/14,39 

   dps is nagato = 3445

MYOKO (CA)
   21.440 every 9,35 sec

   21440/9,35

   dps is myoko = 2295

KAGERO (DD)
   5.436 every 4,31 sec

   5436/4,31
   dps kagero = 1261

BROOKLYN (CL US)
   19.245 every 4,55 sec

   19245/4,55
   dps brooklyn = 4229

EDIT:

ALL DAMAGES AND RELOAD TIME ITS WITH LAST WEAPON UPGRADE 

PS: DPS = DAMAGE PER SECOND.