Marine P.R.D(Percussion Rotary Drill)

The rotary-percussion drill combines both the rotary (grinding) and percussive (chipping and hammering) action. A hole is formed when energy is transmitted pneumatically through the drill rod to the drill bit, prompting it to thrust into the formation using a repeated hammering motion. The impact of the percussion component is enough to break and dislodge rock, which subsequently removes debris and cuttings with compressed air or water flow.

This method works best on rock walls that are solid and dry. Problems are caused with the vibration of the drill string or the abrasion from cuttings in that they may contaminate samples. The rotary-percussion drill is capable of drilling through the hardest consolidated formations, including gravel, quite quickly.