Dropped object to sea during overside rope access operations

Once the technician was connected to the ropes and outboard he was passed the coating gun which he tethered to his harness using one of his available cowstails, however the technician did not identify that the gun was attached via a quick release connection mechanism. The coating scope went ahead with 4 of the 6 tie in points successfully re-coated before the coating cartridge depleted and had to be changed out. The technician positioned himself to ascend the rope, he positioned the coating gun to his right hand side. After the technician had successfully commenced his ascent he was alerted by a team member that the gun had disconnected at the quick release and dropped directly into the sea.