Offshore drilling installation comprising a platform selected from the group comprising a vessel, a pontoon, a jack-up, and further comprising a drill string drivingly connected with said platform and optionally provided with a heave motion compensator, wherein at its lower end the drill string is pro-vided with a drill bit, and wherein a seabed template suspended with lift wires from the platform is placed on a seabed, and wherein clamping means mounted in the seabed template are provided for fixing the drill string relative to the seabed template, which clamping means are embodied as a chuck which is arranged for clamping the drill string whilst enabling the drill string's rotation.