This is a rubber band propelled boat.
You have to print twice parts A and B.
Fix the support to the main part, fetch two rubber band, they must go through the wheel's axis , the support and the two parts 1, Fix the rubbers using parts B. In the wheel's axis, there is a separator, the rubbers must be on each side of it.
Wind it up, put the boat on the water and release...
The wheel roll far to fast, I wonder how to slow it down...