Forget the radar. We're talking sonar here.
Des is keeping the team below the thermal layer just off the continental shelf, where the hull-mounted sonar transmissions merely hit the layer and bounce back up. HMAS Sea Eagle, after some earlier (and totally unnecessary) active transmissions, has gone from Patrol to Search and ultimately to the Ultra Quiet State, sound mats in place, unnecessary machinery switched off (to maximise passive detection ranges) and with all unnecessary movement kept to a minimum.
He is keeping the boat at six hundred feet and is unlikely to return to the roof or PD (Periscope Depth) until approximately 2030K on Saturday, 10 Sep 11. The first green grenade, signifying commencement of hostilities, to be launched from the forward Submerged Signal Ejector (SSE) shortly thereafter.