Three four and three quarter inch by nine inch by five inch stroke inverted-vertical double-acting compound surface-condensing marine engines operating at 420 revolutions per minute on steam supplied at 130 pounds per square inch by horizontal marine boilers with steel tubes, were built by A G Mumford, Culver-street Ironworks, Colchester, for Forresst and Son, boat builders, Norway Yard, Limehouse, who had installed them in three life cutters, built for Sir William Armstrong, Mitchells and Company.