While leisurely driving, barely on plane, approximately 20 mph, we struck a hard, submerged immovable object.  Evidence of damage and sound of impact confirm that object is iron.  In discussing accident with people, there have been stories of previous accidents where boats have had lower units torn off.  Speculation is, there is a sunken barge or old saltwater barrier there.

Boat and motor struck object and was immediately stopped, throwing all passengers forward.  Injuries were bumps and bruises but could have been much worse if boat was travelling faster.  

Motor kicked up and slammed onto rear deck of boat, torque stressing and cracking the transom, jack plate damaged, motor damage to top and bottom.  Bottom/aft 6" of keel struck object before striking the motor.
Beaumont                      