 After the sinking of "Hydro" in 1944, "Ammonia" had to do the main hauling across the lake, and by September 1944 she was performing eight round trips each day.In 1951 the coal boilers were replaced with petroleum-fueled ones.When the diesel-powered MF "Storegut" was launched in 1956 "Ammonia" was down-graded to a reserve ship, mainly serving when "Storegut" was for repairs.