Propellers

Nothing is more important to the proper performance of your Stingray than the condition of the propeller. Even minor damage can adversely affect the boat's performance. The following information will provide you with answers to some of the most frequently asked questions about propellers.


What propeller will get the best performance for hole shot, midrange and top end?
There is no perfect propeller. Correct propping for a Stingray Boat is going to involve a compromise between hole shot, midrange and top end performance. Depending on the specific boat/engine combination, some propellers will perform better than others at attaining all three objectives. The best hole shot is generally achieved with a propeller that allows an engine to gain rpm as rapidly as possible without detrimental ventilation or slippage. BLACK MAX, ALPHA and HIGH FIVE are excellent propeller families that would fit this application. Most engines develop maximum horsepower within the recommended wide open throttle range. Within the range, however, horsepower is usually increased with rpm. The propeller uses power to transfer a higher propeller pitch (inches traveled per revolution), and more rake(bow lift) into more speed with a result of lowering engine rpm at wide-open throttle operation. Mercury offers many excellent performance propellers including LAZER II, MIRAGE PLUS, and the BRAVO ONE Performance Series. Mid-range performance is a compromise of the above two applications. Choose the propeller with the larger diameter that allows the engine to operate in the upper rpm range.
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What propellers are recommended for my Stingray?
BLACK MAX 
A great value and a real performer, this three-blade, black, high gloss premium aluminum propeller is designed for your Alpha Drive or one of similar power. The Black Max is equipped with the patented Flo-Torq II Drive Hub System for improved durability. Exclusively blended aluminum also makes the prop easy to repair.

ALPHA FOUR-BLADE
The Alpha is designed to enhance the all-around performance of Alpha Sterndrive-power boats.   These four-blade, high-gloss, black aluminum propellers practically grab the water compared to three-blade props. The results are noticeably improved acceleration, smoother running quality and a higher level of reverse thrust and docking characteristics. The patented Flo-Torq II Drive Hub System protects the drive train and improves durability. For the power hungry, Alpha One four-blade Performance Series props are quicker to plane with water skiers and heavier loads. The four-blade ALPHA is the nearest competitor to Mercury's SS High Five propeller in low-end performance. Top speed will likely be reduced by 2 to 3 miles per hour.

MIRAGE SS
These three-blade stainless high-performance cup props are excellent when it comes to all around performance and the Duratec finish helps resist metal fatigue and corrosion. Improved acceleration, better holding and a closer match of speed on dual engine boats are achieved through redesigned cupping. For up to 415 h.p. Bravo I MerCruiser Sterndrive boats; the Mirage Plus Flo-Torq II propeller offers robust top-end performance, and the patented Flo-Torq II Drive Hub System. Extensive testing by Stingray has shown running Mirage propellers on Alpha drives usually results in a overall loss of performance (especially low and midrange).

BRAVO III SS
Double the propellers, double the fun. No matter how you use your Bravo III drive, these counter-rotating twin stainless steel props provide exceptional boat handling at various speeds. Improved operating efficiencies and high-thrust production make these props perfect for any Bravo III application, from heavy pleasure and light commercial to the high performance speedsters.

LASER II SS
For those light, easy to lift hulls with plenty of power aft, try a stainless steel Laser II. This performance-oriented, surface-piercing, high-gloss propeller line features the exclusive Flo-Torq II Drive Hub System to protect the drive train and improve durability. Designed to deliver the best top speed your engine and boat package will produce, LASER II is available in a full compliment of pitches for Alpha Sterndrives. Laser II has thinner blades to minimize drag and deliver exceptional acceleration. A small hub version is available so that inline outboard owners won't miss out on any of the action.

HIGH FIVE SS
If you're footing or boarding, the HIGH FIVE series is an excellent blade for towing. The smoothest running prop available for Alpha Sterndrives, with outstanding acceleration to get the boat on plane and the skier out of the water. Five stainless steel blades are the prop of choice for those who depend on performance including nationally ranked tournament anglers, pro water skiers and flats guides. The large hub version is perfect for bigger V-6s and Alpha drives. The patented Flo-Torq II Drive Hub System improves durability and protects the drive train, no matter what brand is mounted on your transom. The HIGH FIVE SS is the best accelerating low and midrange propeller Stingray has ever tested.
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What is propeller diameter?
Diameter is the distance across the circle made by the blade tips as the propeller rotates.
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What is propeller pitch?
Pitch is the distance that a propeller would move in one revolution if it were moving through a soft solid, like a screw in wood. When a propeller is identified as 13 3/4 x 21, it has a 13 3/4" (35 cm) diameter with 21" (53 cm) of pitch. Theoretically, this propeller would move forward 21" in one revolution.
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What is propeller cupping?
When the trailing edge of the blade is formed or cast with an edge curl it is said to have a cup. Cupped props will usually allow a faster top speed and more midrange efficiency by allowing more positive trim with less prop slip. Cupping benefits are so desirable that nearly all modern recreational, high-performance or racing propellers contain some degree of cup. Cupping will usually reduce full-throttle engine speed about 100 to 200 RPM below the same pitch propeller with no cup. A propeller repair shop can increase or decrease cup to alter engine rpm to meet specific operating requirements on most propellers.
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What is propeller ventilation?
Ventilation occurs when air from the water's surface or exhaust gases from the exhaust outlet are drawn into the propeller blades. The normal water load is reduced and the propeller over-revs, losing much of its thrust. This action most often occurs in turns, particularly when trying to plane in a sharp turn or with an excessively trimmed-out engine or drive unit. Ventilation can also be caused by aerated water from step bottom hulls. Stingray Boats' exclusive z-plane hull's bottom allows for less propeller ventilation than boats with conventional hulls.
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What is "blowout?"
Many high-performance boaters are aware of a phenomenon that limits their top speed below what would otherwise be possible with the available horsepower. This phenomenon is commonly called "gearcase blowout," "propeller blowout," or just "blowout." The current gearcases used by Stingray Boats will not "blowout" under normal conditions with maximum available horsepower.
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What is propeller cavitation?
As a shape passes through water at an increasing speed, the pressure that holds the water to the sides and back of the shape is lowered. Depending upon the water temperature, when the pressure reaches a sufficiently low level, boiling (i.e., the formation of water vapor) will begin. The collapsing action, or implosion, of the bubbles releases energy that chips away at the blades, causing a "cavitation burn" or erosion of the metal.

The initial cause of the low pressure may be nicks in the leading edge, too much cup, sharp leading edge corners, improper polishing, or, sometimes, poor blade design. Massive cavitation by itself is rare, and it usually is caused by a propeller that is severely bent or has had its blade tips broken off resulting in a propeller that is far too small in diameter for the engine. (See Ventilation for another common cause.)
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Will a stainless steel propeller make my boat faster?
Generally, yes, a steel propeller will be faster. If the designs are the same, the steel propeller can be made with thinner blades that run faster and with greater strength. Also, most stainless steel propellers take advantage of performance enhancing designs to gain even more advantages over aluminum.
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How do I select the right propeller?
Best all-around performance is achieved when wide-open-throttle (WOT)engine operation occurs near the top of the wide-open-throttle rpm operating range designated by the manufacturer for that specific engine (See Stingray Powerboats power options). Improperly propping an engine can not only reduce performance, but also, in fact, damage the engine.

An engine that does not reach the rated rpm at wide-open-throttle is in an "over-propped" condition, resulting in "lugging." This severe strain can lead to detonation, piston seizure, and engine damage. On the other hand, an engine that revs past the recommended rpm will have higher than normal wear and can also be damaged by fatigued parts breaking and passing through the engine.  This is why it is so critical to be sure your engine is propped correctly for your boat/engine combination and the type of boating you want to do.

To make this selection, propeller charts are published as guidelines for general applications of Quicksilver propellers. They are not intended, however, to be an absolute recommendation, as boats and operating conditions vary. Use the guidelines suggested here, but remember, the best propeller for your boating needs, can be determined only by experimentation.

You really should have more than one propeller if you use your boat for more than one type of activity, such as cruising, fishing, and skiing. You may well need different propellers for the best performance in each type of activity. In any event, you should keep a spare propeller on board at all times, along with a wrench that will fit the propeller nut, pliers, a spare nut, and tab washer.
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In switching from an aluminum to a stainless steel propeller what pitch stainless should I go to?
The most important concern to be aware of is the correct rpm range for your engine. The propeller pitch regulates the engine rpm. Lowering the propeller pitch (going from a 23 pitch to a 21 pitch) will increase the engine rpm, just like shifting from third gear into first gear. Increasing the pitch (23 pitch to a 25 pitch) will decrease engine rpm. Most applications will match up pitch to pitch and this is the best starting point. Changing from Black Max aluminum to a Lazer II SS will usually decrease maximum rpm between 50 and 100 rpm and increase top speed by 2 to 3 mph. If your aluminum was operating in the mid rpm range for your engine, the next lower pitch Lazer II propeller should be best for you. Changing from Black Max aluminum to a High Five SS the rpm should hardly change. In most cases when moving to a High Five from a 21" 3 blade aluminum at the top of the rpm range test at Stingray have shown a 23" to work best. This would seem to contradict previous information. The 23" High Five has exhaust vents, which the 19"and 21" pitch High Five props do not have. These vents allow the 23" to slip at low rpm allowing the engine to make hp quicker and to accelerate as well as the 21" without vents. In most of these cases the 23" will use less fuel at cruise and have a faster top speed.
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If I go from a 3 blade Laser II to a 5 blade High Five would the pitch remain the same?
When comparing the High Five with the Laser II of the same pitch, the rpm of the High 5 will usually be 150 to 300 RPM higher at WOT. Blade design and diameter are two of the indicators that will tell how one propeller will perform vs. another.
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If I try a different propeller and it doesn't perform, can I send it back?
No, we do not have an exchange program once a propeller is run on an engine, it becomes a used propeller. We have no provision to deal with used propellers.
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How should I maintain and service my propeller?
Essential to good propeller maintenance is periodic inspection to detect even small dings, which can lead to blade failure if not dressed or repaired. A damaged propeller, even one that only appears slightly damaged by running through silt and sand, can significantly reduce performance efficiency and fuel economy, and can more severely damage itself through cavitation erosion emanating from the blades' irregular leading edges. In one test with a damaged propeller, top speed fell more than 13%. Acceleration was off over 37%. Optimum cruise miles slowed 21%. Worse yet, damage usually is not done to each blade uniformly and, therefore, the damage can set up imbalance vibrations that can cause fatigue damage to other parts of the engine or drive. If you boat in shallow or rocky waters, you will want to check your propeller more frequently for possible damage.
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Why is my stainless steel propeller rusting?
Stainless Steel is just as its name implies -- it "stains" less than normal carbon steel. Only the highest quality stainless steel available is used. Rust can occur under numerous circumstances, including polluted water and galvanic corrosion. This can be caused by the boat, environmental galvanic activity, (i.e. a marina's electrical system), and oxygen depletion which can be caused by shutting off air to the propeller (shrink wrap or wrapping drive/prop in plastic). Since this is a post purchase cosmetic defect and has no bearing on performance, there is no warranty for rust. The rust can be removed with rubbing compounds. A Scotch brite pad is OK but do not use steel wool. The propeller can be polished and sealed with a chrome polish.
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Why is my stainless steel propeller changing color?
A stainless steel propeller that is turning white has been exposed to a high lime and or calcium (oxidation) condition. Readily available commercial products will remove this and keep deposits of calcium and lime away. A coating of chrome polish will help deter this formation.
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Can propellers be re-pitched? If so, how far?
The pitch on most propellers can be changed. On aluminum propellers a maximum change of one inch of pitch up or down is recommended. Stainless steel can be changed up to two inches of pitch, up or down. One inch of pitch equals approximately 125 rpm. Lower pitch to gain rpm, increase pitch to lose rpm. Modifications will void the propeller warranty. The work of individual prop shops cannot be controlled, especially when adding cup.
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I have an older Stingray Powerboat. Where do I find a propeller for it?
Mercury Marine has a propeller guide with props for almost every boat. Mercury part # 90-850674-97 telephone 902-929-5054.
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How does propeller torque produce boat roll?
When observing from behind a boat, the propeller turns clockwise when underway with a normal right-hand propeller. As water resists the clockwise rotating propeller, it causes the boat to roll slightly in the opposite direction (counterclockwise) or down on the left (port) side and up on the right (starboard) side. To offset this slight imbalance, the driver's seat is placed on the starboard (right) side. Boats differ significantly in the degree of their reaction to prop torque.
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My engine will hit the rev limiter, and is equipped with the standard prop as shown by Stingray. Does my boat have the wrong prop?
The standard propeller recommended by Stingray is best for all-around performance under average use. When we select a standard propeller, it is the one with the best combination for top speed, cruising, skiing, etc. In other words, it is a "general use" propeller. No one propeller can give you the maximum performance for "out of the hole" versus "top-end" expectations; one comes at the expense of the other. The only way for you to achieve maximum performance in both categories would be to carry two props, each designed to maximize their respective feature.

For example, if you have a 190L with a 220 HP EFI V6 and a light load, the engine will hit the rev limiter. Replacing the standard 23" propeller with a 25" propeller would reduce the "general use" features of the standard prop and bias the performance to top-end only. You will lose "out of the hole" performance or the low-end torque as it is frequently referred to. The higher pitch 25" propeller will usually produce higher top speed, but is typically unsuitable for adequate planing or water sports usage, particularly as your load increases.

Stingray dealers also have the opportunity at the time of order to select a different propeller. In most cases, the dealer uses Stingray's recommendations.
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Where can I find propeller comparisons?
Trailer Boats magazine featured an article titled Propfest 4.3 that was based around several days of prop testing that we performed near our facility in Hartsville, SC. The goal was to determine which props work best on a performance-oriented 4.3L sterndrive. The test boat was none other than our Stingray 195LR. The article provides lots of prop data...on lots of different props.

Another good source of information for prop comparisons is our Radar Graphs page. Select your model, type of test run, and engine (if applicable). Results will be displayed at the bottom of the page. We've done a lot of testing and collected a lot of data, so this should prove to be a good source of information.
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