BASED ON THE DRIVER'S STATEMENTS AND OTHER OCCUPANTS, IT IS MORE THAN LIKELY THAN NOT THE FOLLOWING EVENTS OCCURED: 

V1 was attempting to dock his vessel when he lost control and struck V2 that was already docked. 

According to V1 he was pulling up to the dock and tried to turn his vessel but accidentally hit the motor of V2 because, something to the effect of, "it randomly lurched forward". 

This caused damage to the port side hull of V1 and damage to V2's motor cowling. The force of the impact pushed V2 into the dock and caused damage to the front starboard side of the vessel. 

Approximate damage to V1 is $2000.00. The dollar amount for damage to V2 is unknown at this time due to possible further below the waterline on the pontoon that hit the dock.
SPOKANE RIVER
COEUR D'ALENE                 