In French marinas, the electricity is included in your daily rate. Also Butane is expensive. So using this hotplate is very efficient. And at 1kw it will not trip out the marina circuit breakers.
In 2010 (our cruise to the Gironde), we were away from mid May to early September, and did not need to purchase any gas. We started with two dumpy cylinders in the gas locker, and another on deck.