Prop History The origins of Mercury Racing Lab Finish and Pro Finish propellers
Mercury Racing has a well-earned reputation for handcrafting high-performance and racing propellers that consistently offer unrivaled performance. That reputation is based on more than 50 years of experience. In the mid-1970s, Mercury Hi-Performance (the precursor business to Mercury Racing) began creating custom racing propellers in its shop in Oshkosh, Wis. These propellers were ordered by boat racers for a very specific application to specs determined by the boat owner. Each prop, or set of props, was one-off, and featured new levels of meticulous balancing and blueprinting. Lab Finishing was a term reserved for the skilled craftsmen at Mercury Hi-Performance and the progression they brought both to propeller design and finishing.
“Propellers are cast objects, and in a raw state have many imperfections,” said Mercury Racing propeller manager Nick Petersen. “In creating a Lab Finished prop, Mercury Racing starts with a raw casting and removes all of those defects. Cup is measured and tweaked to specification along the entire length of the blade, the prop is perfectly balanced, and the leading-edge geometry is fine-tuned. The blades are also thinner than those of a standard Mercury Marine prop, numerous points of thickness across each blade are measured and precisely matched, which improves dynamic balance, increasing RPM and top speed.
“The Mercury Racing Lab Finish process seeks to make certain that every measurable aspect of each blade precisely matches the others, while taking into account the custom tweaks requested by the customer,” said Petersen. “We take this effort to the extreme in our fully CNC-machined Clever model props, including the new Mercury Racing 300-HP Five-Blade CNC Cleaver. Rather than start with a casting, these props begin as a stainless steel blank with one-inch thick blades, which are then cut down to shape using 5-axis CNC machine tool. There are no irregularities and infinite possibilities; it’s the ultimate Lab Finish.”
A cast Lab Finish propeller may cost $800 to $1,000 more than a standard prop, but it delivers optimal, no-compromise performance. Ideal for lightweight high-performance boats capable of speeds over 80 mph, with Lab Finish props the boat owner can step up in pitch, with a corresponding increase in top speed. Maintaining this performance requires periodic prop maintenance. With use the thin, crisp leading blade edges begin to round off and need to be freshened to maintain peak performance. This work needs to be done by an expert prop shop – Mercury Racing often recommends Frank and Jimmies Propeller Shop in Ft. Lauderdale, Fla., for these tune-ups.
Not every boat can utilize the performance gain offered by a Lab Finish prop, and not every owner wants to make that investment. It was former Mercury Racing propeller manager Scott Reichow who in 2011 proposed Pro Finish, a new line of props that would split the difference between a stock Mercury propeller and a Mercury Racing Lab Finish prop.
“Like the lab finish props, the Pro Finish propellers start as a raw casting from the Mercury Plant 98 stainless steel foundry,” explains Petersen. “We blueprint the cup, achieve zero balance, and the blades are slightly thinner on the leading edge, but not as extreme as a Lab Finish prop. The result is usually an increase of 2 to 3 mph in top speed and 150 to 200 RPM over a stock prop, for about $300 more than a stock prop. It’s a perfect solution for the boat owner who can benefit from an upgrade over a stock prop, but doesn’t care to invest in absolute, optimal performance or deal with prop maintenance.”
Mercury Racing Pro Finish props are also offered in designs not offered in the stock propeller line, with different barrel lengths, vent holes, and half-inch pitch increments that improve performance in some applications. Mercury Racing offers six versions of the popular Bravo propeller series, for example. The Mercury Racing Rev 4 XP, an ideal prop for many multi-engine, high-performance center console boats, is presently the most-popular Pro Finish prop, but the Rev 4 XP is also offered in Lab Finish for boat owners who want to extract even more performance. By offering numerous dedicated part numbers associated with these different modifications, Mercury Racing is able to offer an array of custom, hand-built propellers that are available to order from any Mercury Authorized Dealer.
Mercury Racing is proud to continue its heritage of fine tuning propellers by hand and offer every boat owner a Wide Open boating experience.
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