Ultra-Props work great on small airboats, bowfishing and flounder boats, ultralights, hovercraft, and more. They’re compatible with hubs using between 2.25″ and 3.25″ bolt circles (including the standard Rotax 75 mm pattern we use on our belt reduction drives). There’s also an optional direct drive adapter that allows the Ultra-Prop to be mounted directly to the output shaft of an engine.
Note, it is important when selecting and installing an Ultra-Prop to ensure the propeller is not being spun past its rated rpm. For direct drive propeller on engines governed to 3600 rpm, the typical maximum propeller size is 42″. We recommend installing a digital tachometer to monitor engine/prop speed, especially on engines that have had the governors removed.
*To determine whether you need left-hand or right-hand blades, imagine sitting DOWNWIND of the propeller (i.e. behind the craft for a pusher installation, or in the cockpit for a tractor installation). If the propeller will be turning COUNTERCLOCKWISE, this is a LEFT-HAND propeller. If the propeller will be turning CLOCKWISE, this is a RIGHT-HAND propeller.
Remember that gearboxes reverse the propeller rotation direction and belt reduction drives do not. Cut blades are non-refundable, so if you have any doubt please contact to make sure you are purchasing the right blades.