Fold a paper boat from a sheet of A4, launch it down a rain gutter, and watch its metacentric height decide whether it survives. Exact hydrostatics in the browser: the metacentre is recovered from a heeling simulation that was never given the formula, then checked against BM = I/V. A wider boat is stiffer and rolls faster; the widest boat is not the safest. Independent reimplementation of nothing - the reference is a traditional paper boat, which has no author, no year and no publisher.

Every public app is built from a security-scanned skill and must pass a clean scan — skill and frontend — before it can be listed. Have a skill of your own? Turn it into an app — or read the step-by-step walkthrough.