They are usually up within a week. You can access abstracts of these patents on the US PTO system , or full details, including drawings on pay systems, such as Micropatent . Skin friction reduction by micro-blowing technique . Use of small air bubbles to reduce hull friction. Iriono and Sumino assignors to Sanshin Marine propulsion device including counter rotating propeller blade design for partially surfacing drive .
Patent details a blade design to allow closer placement of the props.
See also patent 5,807,151 above. Nanaka assignor to Sanshin Cylinder disabling control system for multi-cylinder engines . Automatic monitoring of engine turns off some cylinders when power requirements are low. Federal Republic of Germany. Cover for boat propulsion units .