Propulsor

A propulsor is like a special type of fan or engine that can help move boats or submarines in the water. It's a bit like the way a fan helps make air flow, but it works in the water instead. A propulsor might have blades or fins that spin or move back and forth really quickly to push the water around and help the boat or submarine move forward. Just like how you need to paddle to move through the water when you're swimming, boats and submarines need a propulsor to help them move quickly and efficiently through the water.