Summary

The Miranda was a steam launch built by Sir John Isaac Thornycroft c. 1872 for Baroness Adolphe de Rothschild. It converted into the Rap and in this form is considered one of the first true torpedo boats.

Thornycroft's steam launch Miranda (length 50 feet overall, beam 6 feet 6 inches, draught 2 feet 6 inches; trial speed 18.36 miles per hour), was fitted with a 6-inch by 6-inch stroke twin cylinder inverted-vertical simple marine engine, operating at 600 revolutions per minute with steam supplied by a locomotive boiler. The Miranda had a directly coupled propeller 2 feet 6 and a half inches in diameter, pitch 3 feet 4 inches.

F. J. Bramwell's experiments with the Miranda in 1872 proved that it was not axiomatic that high speeds could only be attained by vessels of great length.