During deliberations in late April, "Project I" emerged as the favored design since it would be cheaper than "II" (which would also require widening of the Kaiser Wilhelm Canal). The design was refined into two versions, "IA" and "IB", with the former using casemates and the latter using single turrets. Wilhelm approved "IA" in May, though the arrangement of the secondary guns proved to be contentious, and in December another variant, "7D", which moved eight of the guns to twin turrets and adopted an improved underwater protection system was submitted, which the Kaiser approved on 7 January 1904. These plans were disrupted immediately when the Germans learned of the characteristics of the British s, which carried a secondary battery of ten guns, and estimates of the next class of battleships, which were to carry an even more powerful armament. This meant that "7D" would be insufficient to counter the next generation of British battleships, and the design staff would have to start over.