Jeanneau Leader 9.0 — 35% Faster at 3500 RPM w/ Sharrow Props
The Jeanneau Leader 9.0 seen above — powered by twin 200-hp Mercurys with conventional props — gets on plane between 3700-4000 RPM, depending on her load. But, when fitted with Sharrow props, she got on plane at 3300 RPM in recent tests. At 3500 RPM, she went 23 mph with the Sharrows, but with conventional props, she managed only 17 mph, not yet on plane.
About the Boat
The 29’11” Leader 9.0 has a 9’9” (2.98 m) beam and a dry weight without engines of 5,483 lbs. (2,487 kg). With twin Mercury 200/250-hp engines and a full fuel tank (150 gal./570 L), she had an estimated weight of 7,437 lb. (3,380 kg). Once ground tackle, normal gear, water, beverages and four people were aboard, she will displace about 1,000 pounds (454 kg) more.
Michael Peters was the boat’s designer, and he is at the top of his profession, so owners can rest assured that this boat’s bottom, which has a 19-degree deadrise at the transom, is as good as they come in class. That’s why Jeanneau hired him.
The Test
All test numbers presented here were furnished to BoatTEST by Sharrow Marine and were not recorded by BoatTEST. Nevertheless, we have seen how Sharrow Marine tests boats and we have a high degree of confidence that these numbers can be repeated given the same conditions.
As can be seen in this chart, with the Sharrow props (blue line) the Leader 9.0 is faster at all RPM except at 5500 compared with the traditional 4-blade 14.6 x 15 props.
With the Sharrow props on, the boat was traveling at 23 mph at 3500 RPM. With the conventional props, it could only reach 17 mph — just on the cusp of getting on plane. Because the Sharrow props create more thrust, the Leader 9.0 was 35% faster with those props at that RPM.
With the conventional 4-blade prop, the boat did not get solidly on plane until about 3700 RPM.
The fuel economy improvement of the 9.0 with the Sharrow props was even more dramatic.
As can be seen in the graphic above, the Sharrow props provided more miles per gallon at every data point. The boat was 31% more fuel efficient at idle, where, according to ICOMIA, 40% of the engine’s hours are accumulated. At 28 mph, which for many boats in class is a comfortable cruising speed in a wide range of sea conditions, the Sharrow props were 39% more fuel efficient. At 32 mph, the Leader 9.0 was 18% more fuel efficient with the Sharrow props.
The natural corollary to fuel economy is range. This is where we see the dividends paid by the Sharrow props. Again, at the critical speeds of 28 mph and 32 mph, the boat could travel from 71 miles to 32 miles farther with the Sharrow props, respectively.
The Leader 9.0 was primarily designed for a family adventure, which means cruising into waters for the first time, where fuel docks may be few and far between. Also, most fuel docks have set hours of operation, many close after Labor Day, and relatively few are open in the shoulder seasons. That’s when a boat’s range can become critically important.
Smart operators will plan their trips with range in mind between pit stops, and with the Sharrow props, the boat owner has a greater area of operation. Those 71 miles at 28 mph could make the difference between a great weekend vacation and an island too far.
Advance Rate is the Secret
The question always begs as to why the Sharrow props can perform such seeming miracles, and the reason is that they have a greater “Advance Rate.” That term refers to the distance the prop actually travels through the water with each 360-degree revolution. The “pitch” of the prop is the theoretical distance the prop would “advance” if it were moving through a solid.
But water is not solid, and the actual advance rate is much less. In the example above, both props have a 15” pitch. That means that, theoretically, they should each move forward 15” with each 360-degree revolution. But, in fact, they advance less.
Every Inch Counts. Starting at the left side of the chart above, note that at 1000 RPM, the conventional props move forward 7.81 inches and the Sharrow props advance 9.77 inches. That means, when equipped with Sharrow props, the boat will move forward exactly 1.96 inches (9.77” vs. 7.81”) more with every revolution than the traditional designed props. At 1000 RPM, the boat with Sharrow props will travel 1,960” or 163’ farther every minute.
"True Advance®"
Likewise, at 4000 RPM, the Sharrow prop is advancing 13.68” per 360-degree revolution and the conventional prop is only advancing 11.23” or 22% less. That means at 4000 RPM, in one minute, the boat equipped with a Sharrow prop will advance 816’ farther than the one with traditional wheels.
"Slip" is the Converse of "Advance"
While the term “Advance Rate” was not in common usage among boaters, the term “slip” has long been acknowledged to describe the phenomenon. In the chart above, we see the amount of slip in inches seen in the “Advance Rate” chart, reduced to a percentage less than 15” in the case of each prop.
To be read: at 4000 RPM, the conventional prop (red line) advanced 25% less than 15” per 360-degree revolution, and the Sharrow prop (blue line) advanced just 9% less than 15” per revolution. Thus, we have “Slip Rates of 25% for the traditional props and 9% for the Sharrow props in this application.
A reduction in slip results in a higher advance rate and that’s what allows the Sharrow Propeller to continually deliver improved fuel efficiency and greater range across a wide variety of boat/motor combinations.