I’ve always loved the Eureka Magazine Coffee-time Challenge (although I don’t always agree with the published solutions).
The most recent one is about how to launch boats in bad weather and/or when the tide is far out.
Today’s invention is a large tyre-like ring. This starts onshore in a lagoon (right side of the diagram). The ring would be part-submerged (perhaps even tipped to one side) and the boat sailed in onto the water it contains.
The boat’s propeller drives it up against the ring’s front wall and the whole system moves out of the lagoon and rolls down the beach.
When the wheel hits the water, the ring submerges, disgorges the boat and waits for it to return.