On 26 February 1652, the Jonge Boer Jaap (Jan van Nes), commanded the small frigate, the Gelderland. At least, the 26 February 1652 Rotterdam admiralty manuscript says that. The details are:
Ship: Gelderland
At Date: 2/1652
Captain: Jan van Nes de Jonge Boer Jaep
Guns: 20
Admiralty: Rotterdam
Length (Maas feet): 100ft (Amsterdam feet): 109
Beam (Maas feet): 23ft (Amsterdam feet): 25
Hold (Maas feet): 8ft (Amsterdam feet): 8-3/4
In August 1652, Lieutenant Jan van Nes commanded the ship Gelderland (26 guns, crew 90) in Michiel De Ruyter's fleet. This was said to be the Jonge Boer Jaep's ship. I believe that the Lieutenant actually was the younger Jan Janszoon van Nes, but that is somewhat unclear.
Dr. Elias makes clear, in Schetsen, that there were two men named Jan Jacobszoon van Nes. There was the "Oude Boer Jaep" and there was the "Jonge Boer Jaep". On 7 July 1652 (new style), he wrote an intelligence report from Gravesend, listing the English fleet. This was eventually passed to Lt-Admiral Tromp. On 12 August 1652, his ship was lying mastless, at Havre de Grâce, after a collision that sank the Friesland ship, Sint Nikolaas (23 guns). Apparently, J.C. de Jonge, in Vol.I of Geschiedenis van het Nederlandsche Zeewezen has more information on page 771 and beyond.
