The Rohan class was only ten years old, but the advances made during World War One, had made them virtually obsolete. New ships of a similar type were required. The four ship Tower Class were designed 1923-24, with the first ship being laid down in 1924 and then one per year thereafter. The final ship of the class being completed in 1930. These ships were all that the Senate would let the Zealandian Navy build during this period. The Zealandian Admiralty could only watch as the rest of the world built 8" gun cruisers while they could only build their cruisers with six 6".
The design was a standard two forward, one aft twin turret configuration with single 4" AA and a pair of the new quad 2 pounder AA guns, while a pair of single 2 pounder guns were mounted on either side of the bridge. The speed of the Zealandian cruisers was increasing from class to class, Rohan class 26 knots (28 after rebuilding), Celeborn class 30 knots, while the Tower class all made at least 32 knots on trials. The 6" twin turret was of the new type originally designed for the N3/G3 series of capital ships. These guns fired as far as the previous 7.5", 26,000 yards at 45 degrees elevation.
Designed as patrol cruisers, they were fitted with aircraft handling facilities. A set of torpedoes on each beam gave some teeth against larger targets. These ships had some of the first HACS units fitted to control the 4" AA guns.
