Finding the right propeller for your boat is like playing roulette. You really don’t know what you’re getting until you spin the wheel. Problem is, at a few hundred dollars a turn, spinning these wheels can be a costly proposition. And it’s rare indeed that you’ll get a chance to test propellers before deciding which one to buy. (Mercury is an exception with its demo propeller program.) While the advice is free, it’s not always reliable. Indeed, experimenting to find the right prop is a gamble.
To remove some of the risks, we tagged along when Stingray Boats whisked several bushels’ worth of props down to its test facility at Lake Robinson in Hartsville, South Carolina, to see how they would stack up on the company’s performance-oriented 195LR bowrider.
Powered by a 225 hp Volvo Penta 4.3L GXi/SX sterndrive with 1.60 gears, our 191/2-foot test hull weighed approximately 2577 pounds. Stingray’s sport boats are built for speed and efficiency and are relatively light (compared to some hulls) to eke out every bit of horsepower. And though the props in this test may not be the best for your particular application, the results provide insight into propeller performance and illustrate the effect that props of different pitch and blade count can have.
No one knows how various propellers perform on a Stingray better than company founder and president Al Fink. A hands-on leader with a keen interest in performance, Fink seems as happy, if not more so, when airing out one of his hulls as he is when flying a desk. Not surprisingly, he assisted in gathering all the data during every minute of a project that took up parts of three days. Also on hand was Mark Huddleston, Volvo Penta’s applications engineering supervisor, and hardworking Mike Weatherford from Stingray. Weatherford has been with Fink since the company’s inception 27 years ago and knows better than anyone how to squeeze out the nth degree of speed from a Stingray. He was the sole occupant for each test run — and there were many.
Props were tested for acceleration and top speed with a light load (one person and no gear), and then were evaluated for waterskiing acceleration. Joining Weatherford on the ski runs was a rotund, 300-pound companion: a partially filled 50-gallon water barrel positioned in the amidships ski locker, which simulated passengers. Our skier was a drone named SID (Ski Indefinitely Drone). SID, a water-filled cylinder fastened to a set of skis, proved to be the most tireless, uncomplaining, ill-paid member of the team. In addition, the Stingray’s fuel tank was continually topped off so weights were comparable throughout the tests.
The data was gathered using a Stalker Acceleration Testing System, which combines a Stalker ATS Professional radar gun with a special computer program. The gun recorded the speed, time and distance of the boat at precise intervals, and sent the data to a laptop. The software assigned time information and then calculated distance and acceleration rates for each fraction of speed recorded.
The test included 19-, 20- and 21-inch-pitch wheels in three- and four-blade configurations, as well as one five-blade model. With the exception of a pair of four-blade aluminum props from Volvo, the rest were stainless steel. Besides Volvo, the field included “over the counter, straight from the box” wheels from Precision Propeller (Turbo), PowerTech!, Michigan Wheel and Mercury.
It’s no surprise that the 21-inch wheels ruled when it came to the fastest speeds, but the fact that a four-blade came out on top was interesting. Mercury’s 21-inch Ventura (often called the Offshore Series) four-blade posted a whopping 63.1 mph, edging its next-closest competitor by 2.4 mph. Ironically, Merc touts the Ventura for its bow-lifting attributes and recommends it for 150 to 175 hp outboards and four-cylinder sterndrives. As the test reveals, however, it outperformed all others in top speed on the Stingray 195LR.
We’ve seen situations like this before where a particular hull running under a specific load favors one prop over others.
What’s important to realize is that in everyday use a prop must perform under a variety of loads, so you can’t extrapolate from these results an equally impressive performance in all situations.
Four other 21-inch props (all three-blade models) were able to bring the 191/2-foot bowrider near or just past the 60-mph mark — not a bad turn of speed for a V-6-powered hull. These included: Merc’s Laser II at 60.7 mph; Michigan Wheel’s Ballistic at 60.1 mph; Volvo’s stainless model at 59.5 mph; and Precision Prop’s Turbo at 58.1 mph.
So if you are primarily interested in raw speed and want to outrun your neighbor for fastest-boat bragging rights, the larger-pitch props are the ticket.
OUT OF THE HOLE
The higher-pitch props do not fare as well when it comes to other areas of performance, however. If you want to win a drag race with your neighbor, or are competing in a fishing tournament and need to run short distances to the next honey hole, the 19-inch-pitch props will get you there more quickly than the higher-pitched ones.
But, as distance increases, the 20- and 21-inch wheels will gradually overtake and outrun the 19s.
In terms of sheer acceleration, the light and speedy Stingray showed an appetite for blade area — the more, the better, it seemed. In both the light-load and ski-drone acceleration tests, the five-blade Mercury HighFive proved consistently quickest — but not the fastest on the top end.
The next most competitive wheels varied, however, as the three- and four-blade props were knotted pretty tightly. As just one example, Volvo Penta’s four-blade aluminum and three-blade stainless models fared well across the 19-inch-pitch categories, as did the four-blade Ventura. And while Precision’s 19-inch, three-blade Turbo scored highly in light-load testing, its performance diminished when SID was enjoying a ski.
GIMME SOME SKIN
As stated, the quickest prop in both acceleration trials was Mercury’s 19-inch HighFive, which, along with the 21-inch HighFive, was the only five-blade prop in the group.
In light-load acceleration, the smaller prop was nearly a half-second quicker than its 21-inch cousin from 0 to 20 mph and 0 to 30 mph, and three-quarters of a second quicker from 0 to 40 mph. As expected, however, the smaller prop did not go as fast on top-end: It maxed out at a hair less than 49.9 mph, while the 21-inch HighFive posted 52.8 mph. Whether the 19’s marginally better acceleration is worth losing nearly 3 mph on the top end is a decision individual boaters must make for themselves.
Something else to consider is that while the HighFive’s additional blade area makes for quick acceleration, it also drags down top speed compared to the three- and four-blade props tested.
NEXT ACROSS THE LINE
One of the next quickest props in light-load acceleration was the four-blade Merc Ventura. (Its 21-inch-pitch counterpart posted the fastest top end.) Compared to the 19-inch HighFive, the 19 Ventura was about 0.3 seconds slower in the 0-to-20, 0-to-30 and 0-to-40 mph ranges, and topped out at 50.1 mph.
Running neck and neck was Volvo Penta’s 19-inch three-blade. Its numbers were almost identical to the Ventura’s, but it posted a top end of 53.5 mph, so it turned in a stronger overall, light-load performance.
In turn, the Volvo three-blade was slightly quicker than its four-blade aluminum counterpart — and it earned family bragging rights by being about 1 mph faster. Also putting on a good show was Precision’s 19-inch Turbo, which tied with the Volvo stainless not only for top end but also for having the second-quickest 0-to-10 mph romps.
THUMBS UP FROM SID
With the boat loaded with ballast and the ski-drone in tow, the 19-inch HighFive not only proved quickest in all acceleration ranges, but it also shined in the 0-to-20 and 0-to-30 mph categories — where it was one-half-second quicker than its nearest competitor.
The second-quickest ski prop in the 0-to-10, 0-to-20 and 0-to-30 mph ranges was, once again, the 19-inch Ventura. In the 0-to-40 mph range, however, it slowed considerably, finishing in the middle of the pack. Besides the lightning-quick HighFive, three other 19-inch wheels surpassed the Ventura in this category (listed in order): Volvo Penta’s three-blade stainless and four-blade aluminum, and Michigan Wheel’s three-blade Rapture.
In across-the-board skiing muscle, the PowerTech! 19-inch four-blade and Turbo’s 19-inch three-blade also made strong showings.
Although they couldn’t match the grunt of the 19-inch wheels, the 20- and 21-inch props turned in more than decent skiing times, as well. The Turbo four-blade topped the 20-inch class, while the aforementioned HighFive dominated the 21-inch ski category. Next up was the three-blade Turbo, Volvo Penta’s three-blade stainless and Michigan Wheel’s Rapture. By comparison, Merc’s fast-running Ventura 21 managed only mediocre skiing performance.
FOOD FOR THOUGHT
Volvo’s overall showing indicates that either of its three-blade stainless wheels is a good match for this particular rig, and while its 21-inch aluminum four-blade fell off a little in the ski category, the 19-inch four-blade ran strong in all categories tested. If the price is a consideration, this appears to be a good wheel for this boat.
Ultimately, you’ll have to determine what you’re looking for in a prop — and you should start by asking yourself what you expect a prop to do for your boat. Aboard the 4.3L Stingray bowrider, Merc’s HighFive dominated the acceleration trials but came up short on the top end. The 21-inch wheels had the speed, but not the best skiing grunt.
If it were our boat (and, remember, that the Stingray is a speed merchant), we would be looking at a 21-inch wheel so as to capitalize on this rig’s top-end potential. And based solely on the data, the two wheels that provide the best combination of speed and skiability are the three-blade Turbo 21 and three-blade Volvo 21 stainless.
Given the Volvo’s impressive 1.4 mph top-end advantage, it gets our nod as the best overall performer in Stingray’s 4.3L process.
Take It to the Limit
Stingray President Al Fink’s rule when propping his company’s boats is to find the wheel that offers the best performance when the boat is loaded with four passengers, and full fuel and water tanks (if so equipped). Under these conditions, the prop should let the engine reach the upper range of its wide-open-throttle (WOT) rpm rating, he says. And as a performance-oriented builder, Fink feels it’s OK if the engine is allowed to tickle the rev limiter.
According to Stingray’s data, each of the propellers evaluated (in both light-load and ski-drone testing) either surpassed the 4.3L Volvo Penta’s 4800 rpm maximum recommended limit, or bumped against the 4950 rpm rev limiter. The latter was particularly true of the 19-inch wheels. Even so, Fink reports that many of Stingray’s customers choose a high-winding, smaller-pitch wheel when low-end grunt and the low-speed planning needed for watersports are primary goals.
He also tells Trailer Boats that a 23-inch wheel will likely offer a marginally faster top end than a 21-inch prop (and probably bring WOT rpm within spec), but that the gain is not worth the tradeoff in other areas of performance. A 21-inch wheel offers a good mix of the bottom and top end on this hull, he says.
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