The ship Rotterdam in June 1653

I have always thought that the armament listed for the ship Rotterdam in the Staet van Oorlog te Water for the year 1654 was very odd, indeed. The lower tier was said to be all 18pdr guns, and this on a ship that was 116ft x 27ft x 11ft. The latest information that I have received indicates that in June 1653, the Rotterdam, a ship of the Admiralty of Rotterdam commanded by kapitein Verhaeff's son, Lt-Commandeur Pieter Verhaven, was armed more sensibly, mostly with 12pdr and 4pdr guns.