Prop Venting

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One of the most frequently asked questions on a boat is the prop. “How do I Improve my hole shot”? One way is by dropping in prop pitch or diameter and the other is ventilation. Prop ventilation is allowing the blade to slip through exhaust bubbles from holes drilled in the prop or around the “Hub” or tube that the blade is connected to.   Vent holes only ventilate taking off until the boat is up on plane and have no effect once underway. Vent holes vary in sizes depending on the horse power and boat characteristics. The best way that I can describe the effect the holes have is the comparison of driving a car with a clutch. The bigger the holes in the hub the “more air” which gives more slip like letting your car rev up and slipping the clutch. The smaller the holes “less air” is compared to dumping the clutch and bogging down more. The prop hub diameter has effects on the venting as well. Racing props typically have no tube or what is called a over the hub exhaust prop. This style prop allows a lot of air from the exhaust and around the gearcase to vent the blade and allow the Engine rpms to rev up quicker. This is good for a light boat but not on a heavier boat in most cases. Most boats use a prop with a full or mid tube through the hub prop and control the amount of ventilation with different size holes. Some prop manufactures have adjustable plugs that you can limit the amount of air hitting the blades. This will get you a happy medium. This prop info varies in results. Call us for information on helping you select the right prop for your boat.