Slip is the difference between actual and theoretical movement. It is said to have a cup if the trailing edge of the blades formed or cast with the edge curled. Cupped blades improve the grip of the propeller into the water, reduce cavitation and allow the boat to reach higher top speed. Cupping benefits are so desirable that almost all modern recreational, high performance propellers have some degree of cup. Compared with an uncupped propeller with the same pitch, the cupped one will reduce full-throttle engine speed.
Ventilation is the introduction of exhaust gases into the propeller.
Ventilation can be useful in the bottom end acceleration by allowing the propeller to slip a regulated amount, allowing the engine to rev higher during initial acceleration. Usually achieved by ventilation holes at the base of each blade, or over-hub design. Ventilation is for thru-hub exhaust propellers only. Blade rake is the angle of attachment of the blade to the hub of the propeller. Lower rake is typically used in heavier boats with fully submerged propellers.