Today’s invention is a training aid for surfboarders.
When the weather is too fierce, the surf’s not up or experience is lacking, it offers a ‘dry-slope’ for exponents of this sport.
A cylinder of carpet-like material with a low-friction coating on the outside is supported in a base shaped as shown.
An internal drum rotates, moving the carpet so that it flops inwards on the upper surface, to a degree.
This allows surfers to place their board on the crest of the wave and surf continuously as the carpet rotates.
Apologies, I have applied the arrows to the drum in the wrong directions. Doh.