Talk:World 6/@comment-32271810-20180421111626/@comment-30501447-20180421161129

From the http://kancolle.wikia.com/wiki/Installation page:
 * If those bonuses are from different category, then they are multiplied together
 * For instance, if you equip a regular Daihatsu Landing Craft★1, a Daihatsu Landing Craft (Type 89 Medium Tank & Landing Force)★9 and a Special Type 2 Amphibious Tank onto same DD, then you can get 1.4×2.15×(1+[[1+9]/2]/50)×2.4=7.9464×

So you should equip daihatsus/tanks of different kinds (or a WG42). If you do not have many kinds, use 2 guns 1 daihatsu.