De Ruijter apparently flew his flag on the Lam, at both the Battle of the Gabbard and Scheveningen. I remember seeing, in Salt in Their Blood, that the Lam had 40 guns and a crew of 145 men. In the published list from 1652, near the beginning of the war, Jan Tijssen's ship only carried 32 guns and had a crew of 110 men.
Anyway, we know the composition of his squadron at Scheveningen by the orders he gave to the individual captains.
- Dingeman Cats - Zeeland - Gekroonde Liefde, 23 guns
- Hendrick Kroeger - Amsterdam - Leiden, 28 guns
- Lt-Commander Anthonis Fappenlain - Unknown admiralty - Unknown ship
- Jan Olivierszoon - Veere Directors - Unknown ship, 38 guns
- Gillis Janszoon - Zeeland - probably Zeeridder, 28 guns
- Adriaan Corneliszoon van Ackersloot - Amsterdam Directors - Moor, 34 guns
- Frans Mangelaar - Zeeland - Liefde, 30 guns
- Evert Pieterszoon Swart - Amsterdam VOC - Gerechtigheid
- Bastiaan Centen (Senten or Centsen) - Zeeland - Haes
- Jan Pieterszoon Strijp - VOC, unknown chamber - Huis van Nassau
- Markus Hartman - Zeeland - Gekroonde Liefde, 34 guns
- Jakob Wolfertszoon (Wolphertsen) - probably Zeeland - unknown ship
- Jakob Swart (possibly Jacob Cornelisz. Swart) - Amsterdam Directors - Faam, 28 guns
- Pieter de Bitter - Amsterdam VOC - Gerechtigheid
That would give De Ruijter's squadron a strength of 16 ships, which is plausible.