Expats from within the EU, the EEA (the EU plus Iceland, Lichtenstein and Norway) or Switzerland do not need a work or residence permit for the Netherlands, as citizens of these nations have the right to freedom of movement within each other's countries.
Every non-EU citizen who wants to work in the Netherlands has to obtain a valid work permit. A work permit is valid only for the employer who makes the request and ceases if/when the employee leaves the job. There is no general work permit for the Netherlands. When you start working for Boskalis, “The Relocation Company” will assist you with the application for a work permit.