RedactedNarrative: Vessel #2 was traveling S/B Trenton Channel north on the Grosse Isle Free Bridge at slow no wake speed in the marked channel.  Vessel #1 was traveling S/B Trenton Channel on plane approaching vessel #2.  Vessel #1 Operator said he didn't see vessel #2 until he was right behind it.  He turned sharp to avoid, but the port stern of his boat hit the star board stern of vessel #2.  There were no injuries reported only damages to both vessels.