Today’s invention is a way to enable very small vessels to travel around the world.
A large ship would be built, probably in the shape of a catamaran. This would have a central, raised section linking the two hulls beneath which small craft could travel, under their own steam, or driven by steering the ship so that the prevailing wind passed between the hulls.
Floating booms between the hulls at the front and rear of the ship would effectively isolate the boats from breaking waves and damagingly high oceanic winds.
This configuration would allow people to undertake global-distance voyages without the danger and fatigue which exposed trips would experience.
It might even allow long-distance swimmers the same protection whilst training, for example.