Complex sentence: She could carry 646 passengers, had a top speed of 21.5 knots and was propelled by four medium speed diesel engines; with a combined power output of 18,000 shaft horsepower.
Split into simpler sentences: She could carry 646 passengers, and had a top speed of 21.5 knots. Propulsion is by four medium speed diesel engines with a combined power output of 18,000 shaft horsepower.