14X11 INBOARD PROPELLER DRIVER
14X11 INBOARD PROPELLER FULL

So in addition to getting the boat on plane in less time, the lower-pitch, larger-diameter prop will deliver better acceleration-thanks to better bite in the water. By its own design, that propeller will turn slower and work better with an engine’s low- to mid-speed operating range. If hole shot is a top priority for a client, Johnston generally recommends a propeller that could be one to three inches smaller in pitch than what he would suggest as a speed prop, and one with a larger diameter than that of the faster wheel. Hull type plays a significant role in propeller choice. “For most people, though not everyone, that’s a lot more important than the last few ticks on the speedo.”

14X11 INBOARD PROPELLER FULL

“There’s nothing more embarrassing than having a full load of friends on board your boat at a poker run and not being able to get on plane,” said Johnston.

14X11 INBOARD PROPELLER DRIVER

Regardless of horsepower or gear ratio, a twin-engine 40-foot catamaran with 40-inch-pitch speed props typically struggles to get on plane and requires more than a little driver experience and expertise to make it happen. “In pure speed applications, we generally spec bigger-pitch props with smaller diameters, because that means there’s less propeller surface to drag through the water.” Propping for Hole Shot The problem with small-diameter “speed” propellers when it comes to maximizing hole shot, however, is the same thing that makes them so great for top speed-less overall blade area in the water.

“The higher pitch propeller your boat can pull, the faster your boat is going to go,” Johnston explained.

In the case, the boat would be called “under-propped.” Very generally speaking-because again gear ratios play a big role-the bigger pitch propeller your engine can spin without over- or under-revving, the faster your boat will go. If the prop pitch is too large, the engine could end up 500 rpm or more lower than its capability at wide-open throttle, in which case the boat would be deemed “over-propped.” Conversely, if the propeller pitch is too small to handle the engine’s power, the engine will up hitting its rev-limiter to keep from over-spinning and damaging itself. Generally speaking, when you have big power and you want your boat to run as fast it can, you choose the biggest-pitch prop the engine can turn without compromising its upper end operating range (maximum rpm). Last, there is rake, the angle at which the propeller blade differs from perpendicular (zero degrees or flat). (Gear ratios are typically used to control pitch and manage power, but that’s another article.) The second is diameter, the distance in inches from the tip of one propeller blade on the prop’s hub to the tip of the blade directly opposite. The first is pitch, the theoretical number of inches a propeller moves a boat forward with each complete rotation. Propping for Speed Volumes have been written on propeller technology, but there are three important definitions to understand before getting into goal-specific propeller applications, such as topping for speed. That way, I can make a recommendation that produces the specific results they want.”ĭiameter, pitch, and rake are the three basic elements that have to be factored into every propeller choice. “Although everyone wants to have it all, when I talk to clients on the phone we usually get down to what their true priorities are. “That’s usually my first question to people when they call me: ‘What kind of results or improvement in performance are you looking to achieve?’” Johnston continued. If you don’t care about the last tick or two on the speedo and you boat with a full load of passengers and fuel, then getting on plane easily might be more important to you.

But it won’t be best prop for hole shots or midrange acceleration. “If you’re looking to wring out that last tick on the speedometer, and that’s what’s important to you, we can do that. “I get asked for that kind of propeller three or four times a day,” said Jeff Johnston of Hering Propellers, one of the top names in the go-fast boat propeller manufacturing game, based in Marysville, Wash. But there’s a catch: There is no single propeller choice that is “the best” for top speed, midrange acceleration, and hole shot. As it happens, the most effective way to immediately up the performance of your go-fast V-bottom or catamaran is also the most cost-effective way, and that means replacing your propeller, or propellers in twin-engine applications. They’re expensive, not as expensive as buying a new boat, but expensive nonetheless.

There are all kinds of ways to get “more” in the go-fast boat world-from engine replacement and upgrading to entire hull and outdrive blueprinting-and they, too, have one thing in common. All photos courtesy of Hering Propellers. The quickest path to go-fast boat performance improvement is finding better propellers.

14x11 inboard propeller