Mate that must have been a small tank or your cook alot. Or do you use the oven
part of the cooker as well. Two of us, using just a Gas hobb, had a 9KG last about 4months. When we installed Gas water heating
,(10Ltr/min califont) the usage went to 2months. The califont has the greatest demand on the gas. In the winter, we use the gas heater
a little, but I haven't switched over the tank yet to be able to say how long we got and we aren't live aboard during the winter.