RedactedNarrative: Vessel 1 (Fl#'s) and Vessel 2 (VA#'s) were both on plane going in opposite directions inside "Robbie's wheel ditch" in Islamorada; approximately mm78 bay side.  The water way is narrow and has obstructed views in some sections.  The waterway is marked "Narrow Channel" at both entrances; both operators have been through the wheel ditch multiple times.  The two vessels could not safely pass each other at higher than safe speeds and struck each others port side causing damage to each vessel. no injuries.