So where did the 1644 date come from for the supposed 120ft long Achilles?

Vreugdenhil had listed a ship named Achilles with a 120ft length, built in 1644. From everything I have seen, this was actually the same ship named Achilles, commanded by Dirk Schey in the First Anglo-Dutch War, with dimensions of 131ft x 29ft x 13ft, with a height between decks of 7ft. What has convinced me of that is that Ron van Maanen has a listing for the 120ft ship with dimensions of 120ft x 29ft x 13ft, from a list dated 15 July 1655. The 131ft ship and the 120ft ship listing have more than that in common. The 131ft ship is said to have carried between 28 and 40 guns. The 40 is mentioned by Vreugdenhil, but I cannot account for the number. The 120ft ship is said to carry 28 guns. The crew of the 131ft ship is between 90 and 120 men, as is the crew for the 120ft ship. Neither ship was mentioned after 1655. Sources:

1. Ron van Maanen, unpublished manuscript "Dutch Warships 1600-1800", undated, but circa 1992
2. A. Vreugdenhil, Ships of the United Netherlands 1648-1702, 1938