VehicleBlockCollisionEvent event is not triggered when in a boat:

• I've tested same code with minecart => VehicleBlockCollisionEvent triggered
• Tested by colliding solid blocks around the water => nothing
• Tested by colliding lilipads in water (and so break them) => nothing
• Tested with @EventHandler(ignoreCancelled = false) => nothing

On the contrary (but maybe the attendee result), VehicleEntityCollisionEvent triggers constantly even when NOT moving (I suppose every ticks) between the player and the boat. In a Minecart, it also trigger often but only when moving.

Attached code is a simple class which print in console the name of the event triggered for both VehicleBlockCollisionEvent & VehicleEntityCollisionEvent.

See this discussion:

https://www.spigotmc.org/threads/how-to-check-collision-for-boat.408472