Abstract: This invention pertains to a rotary impact tool which utilizes pressurized eawater as the working fluid. When an operator engages a trigger on a novel control handle and valve assembly, pressurized seawater enters the rotary impact tool through the control handle and valve assembly and a reversing valve into a seawater powered vane motor. The shaft of the seawater powered motor, is coupled to a twin hammer impact mechanism by a novel coupling assembly with rotation of the vane motor driving the impact mechanism which translates vane motor power into impact torque. The impact mechanism is, in turn, sealed within a cavity in the front portion of the housing of rotary impact tool with lubrication and cooling of the impact mechanism being provided by a water soluble oil based lubricant which fills the cavity.