RedactedNarrative: V1 Operator stated he was traveling down the lake when he came across some waves from another vessel; he slowed down and looked for the other vessel.  During this time V1 struck V2 in the stern on the port side.  V2 Operator stated he was traveling at a slow speed when he was struck by V1.  V1 Operator stated V2 did not have any lights on.  Occupant on V2 experienced minor back pain.