An unmanned yacht found drifting off the north Queensland coast had computers running and even food on a table ready to eat - but no crew, puzzled emergency services say.

Rescuers who boarded the yacht this morning noted that three life jackets and the emergency beacon were still on board, but there was no sign of the yacht's life boat.

A massive search and rescue operation is now underway for three men missing from the 12-metre catamaran called Kaz II, which left Airlie Beach in northern Queensland on Sunday.