Are You Under Or Over Revving The Engine
Your boat owners manual will include specs that tell you within which range your boat engine was designed to rev. Itll look something like this: 4200-5000rpm for sterndrive or 50005500rpm for an outboard.
Under revving or over-revving, your engine will damage it faster than you would like. If you find that your boat engine is either under revving or over-revving in contradiction to the specs, the simplest solution is to buy a propeller with the appropriate pitch for your specific boat, which leads us to the next point.
To Pitch Up Or Pitch Down
This is an integral question that must be answered before you buy the new propeller. As explained, by increasing your prop pitch, you will be effectively decreasing the engines rpm and vice versa.
Since the general rule of thumb is that every two-inch increase in pitch decreases the engines rpm by about 400 revolutions, if you find that your boat is under revving, then you might want to consider getting a propeller with a lower pitch and vice versa. If your boats issue is that its over-revving, then getting the 21 pitch propeller might be the best solution.
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The beauty of all this is that your boat manual will have the desired specifications, but you could also ask your mechanic or even your dealer to advise which prop pitch would be the perfect solution for your specific boat. Just remember, one of the most important considerations here is your performance goal. What is it you want the boat to do exactly?
Wholesale Marine Boat Propellers
Selecting the right boat propeller is key to maximizing your boats performance. You might well be pleased with the performance of the propeller that came standard with the motor, but you may be wondering if there might be room for improvement. For advice when selecting the right boat prop for your boat from our wide inventory of competitively-priced propellers, speak to the boating professionals at Wholesale Marine. We stock Michigan Wheel, Turning Point, Bravo and Quicksilver boat propellers to fit Evinrude, MerCruiser, Mercury, Johnson, Volvo Penta, Yamaha, Suzuki, Honda and more. Additionally we offer sturdy stainless steel, lightweight but durable aluminum and traditional bronze boat props for nearly every craft.
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Free To Use Propeller Sizing Calculators
Before you start, we would like to point out that these calculators are based on empirical data.They are not intended to perform complex cavitation or efficiency calculations.The results provide “best size” propeller dimensions based on your input data.There will always be a number of propeller size combinations that will work on your vessel, finding the best one is the trick.These calculators will help guide you to determine various combinations of power, gear ratio and propeller size for your vessel.Dueto the nature of these calculators, Victoria Propeller Ltd. will not accept anyliability, financial or otherwise, for the calculations or resultsprovided.
How To Select A Propeller
Propellers are described in numbers: the first number is the diameter, and the second number is the pitch. So, a 14 x 19 propeller has a diameter of fourteen inches, and a pitch of nineteen inches. In conversation, most people would describe this propeller as a 19-inch pitch, or simply a 19.
Choosing a Propeller
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What Are The Problems You Are Looking To Solve
What are some of the issues you are facing?
- Is your boat sluggish when coming out of the hole, or are you having issues hitting the kind of speeds you want?
- Is it a fuel consumption issue?
- Do you want better all-around performance?
- Maybe your current prop is ventilating excessively?
As soon as you define the problem, you will be in a much better position to find the perfect solution.
Choosing The Right Propeller For You Boat Requires Trial And Error
Often, your dealer can supply two or three props for testing when you buy a new motor for a small fee.
This is because boat design, load and the running characteristics of your vessel all play a part.
Watch our video as we chat to marine mechanic Matt Solis from Barneyss Marine Hervey Bay for some tips and considerations when choosing the right propeller for your boat.
Ryan Moody started his fishing career on the reef boats before catching bucket list marlin for the likes of champion heavy tackle angler Johnno Johnson, INXS and the King of Sweden. Branching out in the late 80’s to guided barramundi fishing, Ryan has made a name for himself as a Big Barramundi specialist and to date has put clients onto over 2000 metre plus barra. That is over 2 kilometres of metre plus barra! With attitudes changing from ‘keep all you can’ towards catch and release, Ryan has decided to share his extensive knowledge and hopefully inspire people of all ages to get out from behind the computer screen/TV and into the fishing outdoors lifestyle he has spent his life perfecting.
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Find A Replacement By Oem Part Number
If you know the OEM part number and basically just need to find the replacement, use the Prop Finder tool. Or search the pages and PDF guides below by your OEM part number to find a suitable replacement. Give us a call at 1-800-998-9508 or Intl. +1-206-780-5670 if you don’t find what you need and our boating experts will quickly help you locate a replacement.
- OEM Cross-Reference Table for Mariner, Mercury Outboard & Mercruiser Stern Drives
- OEM Cross-Reference Table for Mercury / Michigan Wheel / Quicksilver / Turbo / Turning Point
Tips For Knowing When To Replace Boat Propellers
How can you tell if your boat propeller requires replacement? There may be an obvious reason for doing so such as if your prop has sustained visible damage to a blade. However, even when your propeller is performing within manufacturers recommended guidelines, often there is room for performance improvement. Reasons for replacement include:
Close inspection reveals broken or cracked blades. Upgrade to different materials such as aluminum or stainless steel. Upgrade to a different number of blades, from 3 to 4 for example. Upgrade to a larger size boat propeller to improve acceleration and top end performance. Want to carry a replacement propeller on board just in case.
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What Is Hull Resistance
Resistance is the hulls natural tendency to drag through the water. Bare hull resistance is produced by skin friction of the hulls surface, waves created by the hull running through the water and the shape of the hull below the water. To the bare hull, the drag of appendages must be added such as rudders, shaft support brackets, shafts, depth sounder transducers, stabiliser fins, etc. However, the design of the lift surfaces of the hull also have a very significant effect. Designers work to ensure that the lifting characteristics give the hull the least resistance at normal operating speed.
Once this resistance is known, engine and gearbox specifications can be combined with maximum propeller diameter to determine the props minimum requirements. The vessels duty cycle, which is simply a judgement as to whether a boat is to be used for heavy or light commercial or pleasure purposes, then also influences a designers final specification.
Propeller diameter is first decided by the type of boat. A large-diameter slow-revving propeller is the most efficient type but this wont provide the necessary acceleration to get a sports cruiser onto the plane. Acceleration is achieved by increasing the rotation speed, which usually means a smaller diameter propeller. The fact that many modern sports cruisers have limited propeller clearance space is another reason for fitting smaller diameter propellers.
Two Tools For Finding The Right Prop
For help finding the best all-around prop for your boat, start with the Mercury Prop Selector tool, a great resource that in just five steps will help you narrow down prop options for your boat and engine combination. Next, try a new propeller on your boat. More than 100 Mercury dealers in the United States are participating in the Propeller Demo Program that allows a boat owner to test-drive a stainless-steel Mercury propeller and compare, for example, the performance and handling of a three-blade and four-blade prop option. The demo program makes it possible to zero in on the best all-around propeller model and pitch size for your boat before you make that purchase.
Mercury transforms aluminum and stainless steel into the highest-quality, best-performing, most-durable marine propellers in the world. For best overall boat performance, there’s no substitute for a Mercury propeller.
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Select The Right Boat Propellers For Maximum Performance
The drive train is an important system on any engine-driven vehicle, car, truck or boat. For land vehicles, the system concludes at the tires, where the rubber meets the road. There, the choice is simple: select the right tire for the roadway and intended vehicle use. The difference for water-based craft is, of course, that the drive train ends at the propeller which is the liaison of horsepower to the water. Selecting the right propeller is very important. Boat propellers are available in a wide assortment of sizes and shapes. Sizes are referred to in terms of diameter and pitch. To make the best selection, sync the propeller to the manufacturers wide open throttle range. The right propeller will turn the minimum engine RPMs required by the manufacturer with its throttle fully advanced.
The next consideration is diameter. This will also determine the propellers RPM capabilities. Overall engine performance can be improved by selecting the right boat prop. The number of blades is also a consideration. Standard rule is the fewer blades, the faster the vessel, however, this rule is not cast in stone. The deciding factor will always be the particular application the boat is used for in order to determine the number of blades required to achieve the best engine performance.
What Is A Nut Kit
The propeller is fixed on the propeller shaft with mounting parts. A nut kit usually includes a nut, cotter pin, washer and spacer. Normally you only need to replace your propeller and can re-use these parts. In case your propeller is lost while sailing you may have lost these parts as well. The right nut kit is suggested at the product page of the propeller for your engine.
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Solas Propeller Installation Instructions
How To Calculate Propeller Pitch
Propeller diameter is simply the diameter of a circle scribed by the blade tips of the prop.
Propeller pitch is the distance the prop would move forward in one rotation if it were moving through a soft solidthink of a screw being turned into wood. The blades on a propeller are analogous to the threads on a screw. Some propellers have a constant pitch, meaning the pitch is the same at all points from the leading edge to the trailing edge of the prop blades.
Progressive pitch starts lower at the leading edge and increases to the trailing edge. The pitch number assigned to a progressive-pitch prop is the average across the entire blade. Progressive pitch improves performance in high-speed applications.
Propeller pitch determines the final gear ratio between the engine and the water. A boat should be propped to operate within its wide-open throttle , which can be found in the motor specifications or the owners manual. Ideally a motor with a WOT range of 5000-5800 RPM will reach 5400 rpm with the boat running wide open and trimmed out for optimal performance, with a full load of fuel and water and an average passenger load. That RPM may go up with a light load of fuel or passengers, and lower with a heavier loadby propping for the middle of the range there is leeway in either direction.
The best bet is compromise between these extremes, a prop size that puts the engine in the sweet spot of its RPM range for everyday use.
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Is Your Engine Over Or Under Revving
Selecting the correct prop should result in your engine running within the designed rpm range at Wide Open Throttle . Your owners manual should include this specusually 50005500rpm for an outboard or 4200-5000rpm for a sterndriveor your mechanic or dealer may know. Allowing your engine to under rev or over rev at WOT can result in engine damage. Over revving or under revving can be corrected by selecting a prop with a different pitch.
When Choosing The Right Propeller For Your Boat Youll Also Want To Consider The Material Used Number Of Blades And Pitch
A lower pitch allows you to build up RPM quickly which is good for big boats with a heavy load.
But there will be less forward travel with each revolution so not good for top speed.
A higher pitch is slower to build up RPM resulting in lower pulling power and acceleration but a greater top speed once the vessel winds up.
Youll also need to know how to read the prop. Meaning how to identify the size, diameter and pitch of a propeller.
Most props have a series of numbers on the side or inside the hub.
A three blade prop, 18.75 inches in diameter with a 19 inch pitch will have the numbers 3 X 18.75 X 19.
Numbers are printed on the side of your prop tell you the number of blades, diameter and pitch of your prop.
If they are not printed on the side of the prop, look for the numbers inside the hub of the propeller to determine diameter and pitch.
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The 7 Best Boat Propellers For 2021
by Ian ForteyUpdated on August 19, 2021.
Boat Safe is a community supported site. We may earn comission from links on this page, but we have confidence in all recommended products.
Buying a boat propeller seems like it should be an easy task. But there are actually so many factors you need to take into consideration. It can leave you scratching your head. Lets cut through the confusion and take a look at the best boat propellers on the market today.
The Quicksilver Black Diamond is the best all around boat prop youre going to find. Its not too expensive, but its built to last and to perform. In fact, its the best-selling aluminum prop in the world.
This is Quicksilvers 3 blade design. Its right hand and comes in a large range of pitch sizes. You can use this anywhere from 25 horsepower up to 250 horsepower outboard motors. Its also suitable for Alpha One sterndrives. It operates with the Flo-Torq hub system youll find on many outboards.
The included hub will work for engines up to 60 horsepower. If you have a bigger engine, you can pick up a different hub system to get the job done.
Once installed, expect to see a big improvement in planing. This model also offers a solid hole shot. That refers to your boats ability to accelerate. That means from a standstill or just low speed. If you hate slow acceleration, a good hole shot is important.
Choosing The Right Propeller By Crowley Marine
The right prop will get the best performance out of your boat. Matching the propeller to your application, whether cruising, water skiing or performance, maximizes the power from your engine. It also helps with handling and acceleration. Use this guide to learn how different propeller designs affect efficiency, power, and speed and then learn how to choose the correct prop for your boat and application.
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Prop Antifouling Research Spins Into New Territory
A cheap, effective antifouling paint for a propeller is as rare as a good pun. The coating must not only ward off all marine growth, it must present a smooth slick surface that can stand up to the constant water friction when the boat is under power. And in the case of a folding prop, the coating must also adhere in nooks and crannies and, in some cases, even withstand metal-to-metal contact. These demands are well beyond the reach of any run-of-the-mill marine coating. Thus, our search for-wait for it-a prop paint.
Yes, you can paint a bronze propeller with conventional, copper-based hull paint, but it wont do much good, since the more noble metals in the bronze prop will eventually waste away the copper biocide. Dont even think about painting an aluminum outdrives or prop with a copper paint, or the reverse will occur-the more noble copper will attack the outdrive alloys. Even with the right preparation, regular bottom paint tends to wear quickly on a prop due to increased water friction.
Paints for Props and Running Gear
For the past few years, Neeves has been trying to find a paint for props, saildrives, and running gear that matches the life of the antifouling on his hull. The seasonal sailor who hauls and paints every year doesnt need this level of performance, but for a year-round sailor, a good multi-season prop paint can yield big savings.