No, a sailing license is not necessary. Everyone over the age of 18 can rent a boat. It is also not difficult. You have a steering wheel to determine the course. A boat responds somewhat slower than a bicycle or car. Slowing down takes more time. The boats are all around equipped with a bumper. At the front there is a rubber bumper mounted. The most vulnerable part is the propeller. Use caution when reversing close to the side. If the propeller is damaged, you will not get back home, or really late.
The boat steers on the propeller, so always keep some ‘gas on / press it’ when you go through a corner. This is similar to an outboard motor.
Look ahead, take it easy, get used to it and then it will be fine. “Easy does it”.
Very important – do not take a risk on the water – and certainly not with professional shipping. Those big boys can hardly maneuver and stop – so NEVER go near them. Pass by and stay away from the propeller water – If you come close, the boat won’t steer anymore.