 The 20 mm gun that was initially mounted was removed, leaving only three 12.7 mm machine guns.Beginning in 2003, the remaining Dutch "Alkmaar"-class minehunters were upgraded with improved electronics, including Atlas Elektronik INCMS combat data system, Thales 2022 Mk III hull-mounted sonar, Atlas Seafox Mine Identification and Disposal System and a Double Eagle Mk III Mod 1 ROV.The minehunters were constructed at the Van der Giessen-de-Noord yard in Amsterdam, a specially constructed site completed in 1978.