There was a possibility X5 had also successfully planted side charges before being destroyed, but this was never conclusively proven.[9][10] An expedition jointly run by the late Carl Spencer (Britannic 2003), Bill Smith (Bluebird Project) and the Royal Navy using the mine hunters HMS Quorn and HMS Blyth in 2006 mapped the north and south anchorages used by Tirpitz and proved the charge was well inside the net enclosure of the north anchorage and therefore most likely from X6.[11]