All portholes were also removed for two main reasons; firstly to aid the sinking of the vessel and secondly, because the rims of the portholes are made from brass, there were concerns that divers might attempt to remove these for their monetary value. The final stages of preparatory works to the vessel required the removal of all electronic equipment and navigational aids and instruments. All fuels and lubricants which could potentially create pollution once submerged into the proposed site were also removed prior to sinking.
The main mast of the vessel was also removed in order to reduce the overall height of the vessel in order to ensure a minimum of 15m clearance to the surface.
The final preparatory phase for the vessel involved cutting holes throughout the deck and welding all the external metal doors open in order to help sink the vessel. The ship’s main engine and fuel tanks were flooded prior to towing her out into position, as this would ensure that the air pressure in these compartments were equalised during the sinking phase.
The Sun Swale was towed to its final destination by another tug vessel. Once there, the anchors at the bow of the ship were dropped and a line at the stern of the ship was attached to the towing vessel in order to keep her in place whilst she flooded. Once she was sinking, the line attached to the towing vessel was let loose and salvaged later.
Once she was held in position , water was pumped into the Sun Swale from the towing vessel to additionally assist and speed up the process. The sinking process was carried out in a controlled manner with the Gibraltar Port Authority and the DEHCC overseeing the whole process.