On 2/15/2012, at approximately 3:00 pm a 14' open motorboat on Rock Lake was returning to landing.  Rock Lake is a deep and narrow lake that has numerous basalt columns that extend up from the bottom to just near the surface of the water.  The lake level determines how close the columns are to the surface.  As the boat was returning, the motor shaft struck a submerged rock hazard, probably a rock column and caused the motor to kick up from the impact and the stern to rapidly take on water causing the vessel to sink.  

the operator described his location as about 80-100 yards from landing.  Vessel was a total loss and sank in about 300' of water. Both individuals were able to swim to shore and other than hypothermia, received no treatment and had no injuries.
Ewan                          