Too few heavy guns for effective battlecruiser salvos

The Courageous type's main battery is judged too small for effective battlecruiser gunnery. Courageous and Glorious have only four heavy guns, while Furious's intended battery has only two. At long range, a ship needs enough shells in a salvo both to range on its opponent and to achieve hits. On that reasoning, large light cruiser is the more useful description. Another possible purpose is to help force an entry into the Baltic: shallower ships could use water unavailable to the main fleet and give the Royal Navy more room to maneuver.