Initially the West Country keels were equipped with sails that would be used on the Humber or elsewhere if the opportunity arose, the
rest of the time the power being provided by a horse. With the advent of steam, keels began to be built without the provision for sale, these boats often known as "Dumb boats" would be towed in
groups by steam tug on the Humber and horse elsewhere. Steam engines were later fitted to some Keels allowing them in turn to tow a dumb boat. With the arrival of the diesel engine, Mirfields
yards found a new job converting many dumb boats to this means of power in the 1930's and 40's.