Opportunities to visit steam turbine powered ships are now few and far between and the recent scrapping of older passenger tonnage due to stricter SOLAS regulations has not helped. SS Margaret Hill was a liquefied natural gas carrier with the boilers fired on boil-off gas (BOG - yes really). The vessel was built in 1974 by Moss at Stavanger, Norway and fitted with a General Electric cross compound steam turbine of 30,400 horsepower and good for 19.5 knots. In order to fill the gas tanks from empty and also to return them to empty at atmospheric pressure and temperature, it is necessary to use an inert gas to prevent possible explosions. This gas is a mixture of nitrogen and carbon dioxide and is produced by burning diesel in this bit of kit to remove oxygen and produce carbon dioxide. Part of the mechanism is the green device in the middle - a Roots/Connersville blower built by W C Holmes of Huddersfield.