Scarab Jet Boats | Home Scarab Jet boats make every day on the water an adventure to play with sporty, performance, luxury boats. Scarab Jet Brochure Jet Engine. Legendary Rotax® jet propulsion systems make Scarab boats fun to drive, reliable and easy to operate. See Scarab Jet Propulsion. What is a Jet Boat? Advantages/Disadvantages - Smart Boat Oct 13, 2017A jet boat, on the other hand, is much more similar to a traditional fiberglass runabout. In 2018, most jet boats range in size from 16′-24′. The smaller jet boats under 20′ in length typically have 1 engine. The larger jet boats will usually have twin engines.