The SS Erl King was built at A and J Inglis, Pointhouse, Glasgow and launched in 1865 and owned by Robertson & Co London. She was designed as an Auxiliary Steam Ship - steam power would be used to supplement the propulsion from the sails, when there was no wind or if there was a light head wind. She was fitted with a propeller that could be lifted up when sailing, so as to reduce drag. The engine was not powerful enough to push the ship, with all the windage of standing rigging, directly into a strong headwind. Auxiliary steam power had the advantage of allowing this vessel to use the Suez Canal when it opened in 1869 - something which was not possible for sailing vessels.