thumb|Berthon Boat
Berthon Boats are collapsible lifeboats used in the late 19th and early 20th centuries. They have double linings of canvas, sectioned into watertight envelopes that assist buoyancy and give protection from the possibility that the outer canvas could be accidentally torn. The canvas was also coated with "linseed oil, soft soap, and yellow ochre" to make it waterproof.
When the boat was demonstrated to Queen Victoria, the Prince Consort, the Princess Royal and the Prince of Wales, the latter commented that a cannonball would go through it easily. Berthon asked him what a cannonball would not go through, and the Queen was reported to have been greatly amused. Nonetheless, the Royal Navy accepted a perfected design in 1873.