Pick a Propeller - Properly
June 30, 2017
Busted prop? Hey, it happens. As annoying as it is, it's not the end of the world - it doesn't even need to be the end of your boat trip. Where to begin? Your owner's manual will have a lot of the information you need. If you have the manual for your engine, follow the guidelines in it to avoid damage to your boat. You don't need to get the exact same prop, but matching diameter and pitch will help you keep your boat's performance consistent. Luckily, that information is usually stamped on the propeller. [caption id="attachment_419" align="aligncenter" width="300"] Evinrude Nation[/caption] Diameter is easy: it's the measurement of the circle that the blade tips make as they whirl. A too-large or too-small propeller can impede proper engine function or damage your boat. Pitch is a little more complicated. To understand pitch, imagine your boat propeller as a wood screw being driven into a board. The pitch number tells you how far the prop would penetrate in one revolution. A 17-pitch propeller, then, would travel forward 17 inches per revolution. [caption id="attachment_425" align="aligncenter" width="300"] boats.com[/caption] Low-pitch propellers cause your engine to reach peak RPM sooner than high-pitch props, but give faster acceleration from a standstill and work better for heavier vessels. High-pitch props let you reach higher speeds, but acceleration is slower. In other words, you have to choose between low torque and high speeds. [caption id="attachment_422" align="aligncenter" width="300"] greatlakesskipper.com[/caption] What about blades? Three- and four-blade propellers are, generally speaking, interchangeable. For more or fewer blades, you might need to slightly change prop size and pitch to keep your engine's RPM in the proper range. You wouldn't drive your car without a spare tire, so why take your boat out without a spare propeller on board? When you replace your prop, grab an extra one (or set, if you have two or more engines) and stow it aboard just in case. Keep a spare set of tools on your boat, too, for replacing a propeller away from home. Check out the Skipper's tips for help swapping out your prop. If you, like many boat owners, use your boat for different activities, consider purchasing multiple props to maximize performance. For skiing or towing, install a propeller with a install a propeller with a lower pitch. Lower pitched props improve takeoff acceleration getting your skier up and out of the water faster. If your prop is already pitched as low as your engine can handle, consider a 4-blade prop to maximize your motor's low end performance without over-revving it. Each inch of pitch equals 200 RPM, so increasing the pitch decreases your RPM. Choose a lower-pitch prop for heavily-laden fishing trips to avoid excess wear on your engine. [caption id="attachment_415" align="aligncenter" width="300"] greatlakesskipper.com[/caption] Propellers are made from different metals. Inboard props, also referred to as "V-drive" or "Direct Drive" props are frequently made from nibral, an alloy of nickel, bronze, and aluminum. Aluminum props are popular and inexpensive; you can choose among different finishes, too, like black or white. For durability and speed, stainless steel is top choice, but that superior performance means a slightly higher price tag. Luckily, Great Lakes Skipper has boat propellers of all kinds at deep discount prices. For ultimate cost-consciousness, check out used or demo boat propellers. These are props that are shopworn from being used as display models, installed but never used, or have seen light use in tests and demonstrations. Buying a good used boat prop means big savings. Minor scratches, dulled finish, and light oxidation won't hurt your boat's performance, but you'll of course want to skip buying a bent or badly-nicked propeller. A demo prop makes an affordable emergency spare, too. Need more info? Contact us and our customer service staff will be happy to help you choose your next boat propeller.