The Hydro Air Drive™ is a totally new and patented concept in marine propulsion. It has a completely enclosed rotor and an inlet in the boat hull like a water-jet thus offering all the advantages of a water-jet, however, the Hydro Air Drive rotor operates only one half submerged at high and cruise speeds. It can operate fully submerged like a standard water-jet at low speeds to double it's water flow and thereby increase thrust at low boat speeds compared to the smaller rotor standard water-jet.

The Hydro Air Drive has considerable advantages over conventional water-jets :

• Significantly better efficiencies at high and low speed
• Improved low speed thrust since submerging the rotor can double water flow
• No cavitation damage
• Full reverse thrust on the shaft
• Less subject to being incapacitated by debris ingestion.

The Hydro Air Drive is highly efficient at high speeds because the inlet water does not have to bend upward and has less wetted area friction compared to the inlet water flowing into the fully submerged standard water-jet rotor. This means higher inlet pressure recoveries and hence significantly greater overall efficiencies.
Calculations show that efficiencies of the Hydro Air Drive should be at least 20 percent better at high speeds and even more impressive at low speeds compared to a similar power water-jet of conventionally submerged rotor design. The drive is not subject to cavitation since it's aerated at all times.