Aert Jansz Verhaeff's ship Rotterdam in 1653

Aert Jansz Verhaeff commanded the Rotterdam ship named Rotterdam. This was one of the ships that measured 116ft x 27ft x 11ft in Amsterdam feet of 283mm. The usually published dimensions are actually those in Maas feet of 308mm: 106ft x 25ft x 9ft, which are what was reported in the Staet van Oorlog te Water for the year 1654. If you convert to English feet, the dimensions are about 107ft x 25-1/4ft x 9ft. These are measured differently from how the English measured their ships. They length from stem to sternpost x beam inside the planking x hold at the deck edge from the keel. The English actually measured length on the keel x beam outside the planking x depth in hold at the center of the ship. Decks usually had a camber or curvature, so the center was higher than at the deck edge. I estimate the English-style dimensions for the Rotterdam as 87ft-3in x 22ft-4in x 8ft. I would guess that the length on the gun deck, in English feet, was about 112ft. The Rotterdam was like a rather small English 5th Rate. An oddity was that the Rotterdam is usually said to have 18pdr guns on the lower tier. I have a document that indicates that the Rotterdam had 18-18pdr guns. I assume that they had to be very lightweight guns, if this is true. Jan Evertsen's old flagship Hollandia carried four 18pdr guns that were only about 2400 lbs, so maybe the Rotterdam carried similar guns. For that little weight to be workable, they must have used reduced charges. Otherwise, the guns would have been dangerous to fire.