In 1890 four compass manufacturers were invited by the Royal Navy to compete for a new design of boat compass. The specifications required the instrument to be capable of handling the vibrations of a steamboat as well as the usual requirements for sailing and pulling boats. The resulting entries were tested aboard H.M.S. Vernon at Portsmouth. The example offered by DENT was the best on all counts and was introduced as BOATS COMPASS PATTERN 20 in 1892. Apart from a reduction in card size in 1907 the pattern remained in service until after the First World War. The example offered above is a pre-1907 model with the larger card.