Volvo Duo Prop Type T: Advantages

Volvo Duo Props Type T are engineered and designed for use with IPS drives.  Unlike many other propeller systems that are fashioned out of stainless steel or aluminum, Volvo Penta Duo Props Type T are made from a carefully formulated mixture of three metallic substances: nickel, aluminum, and bronze.  Nickel and aluminum are pure metals – indeed, they are elements on the periodic table students learn about in chemistry class.  Bronze, however, is an alloy of copper mixed with other metals, tin among them.

This substance is called Nibral and it has properties that make it ideal for use in a high quality propeller such as those manufactured by Volvo Penta in their duo props line.  Nibral, for example, is able to withstand corrosion, which means that a purchase of a Volvo Penta propeller in the T series can help to yield a propulsion system that will last for many years.  In addition, the use of a strong material such as Nibral combined with a well-thought-out design means that Volvo Penta duo props Type T can provide outstanding performance during its long lifetime.

Sea water and metal can sometimes combine to produce an electrical charge, which can interfere with the full use and enjoyment of a propeller. Such a charge can also contribute to corrosion.  However, the use of the Nibral alloy ensures that the propeller is optimally isolated from electrical charges.

As with all Volvo Penta duo props, the type T series is backed up by an extensive warranty by Volvo Penta.

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Boat Propeller Design: The Issue of “Cupping”

Boat PropellersMany different elements go into the design of boat propellers.  In addition to the diameter of a propeller and the amount of pitch it produces, boating enthusiasts also need to consider issues such as rake, which refers to the angle measured in degrees between the hub and each of the blades on the propeller.   Yet another consideration is the issue of cupping.

What is a “Cupped” Propeller?

Boats props that are said to be “cupped” have a final trailing end that appears to curl away a perceptible amount from the watercraft. This small amount of curl produces a blade tip that appears to have a small indentation or “cup,” hence the term.

Cupping is one of the recent innovations to be added to the design of boat propellers.  When the technique of cupping a blade was first applied, the purpose of it was to augment either pitch or rake but without the need to bend the entire blade, since that can produce unwanted effects.

Benefits of Cupped Blades

As soon as cupping was applied to propeller blades, however, it became apparent that one of its primary effects was to enhance boat performance.  Since a cupped blade tends to produce an increased amount of pitch, it meant that rpms could be decreased without a loss in performance.  This in turn increased motor efficiency.

The increase in efficiency generally depends upon how much cupping is incorporated into a blade design, though the precise location of the cupping is also an important factor.

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Stainless Propeller Shafts

Propeller shafts are just as important for a good boating experience as propellers themselves.  Aqualoy stainless shafts are widely regarded as an ideal component for use in propulsion systems in both pleasure boats and service crafts.  Even naval vessels use this kind of shaft, and for good reason.

Benefits of Aqualoy Stainless Shafts

A shaft is only as strong as the metal it is made from.  The Aqualoy fabrication process begins with molten steel and manufactures it into strong stainless steel that offers superior resistance to corrosion.

Each shaft is finished to exact specifications so that the diameter needed for a particular propeller system is delivered precisely.  The diameter of Aqualoy stainless shafts are also verified for roundness using industry standard techniques.  Another step in the finishing process involves testing for straightness since a shaft that exceeds acceptable tolerances for straightness will not function well and may even cause damage to prop and motor.  Understanding that a straight marine shaft is essential, Aqualoy straightens each shaft until it meets standards.  Another benefit of straightening is that it help the shaft last longer under actual use.

Installation Considerations for Stainless Shafts

Boating enthusiasts who wish to install a propeller on the shaft on their own should coat the shaft taper with Prussian Blue to help test for fit and use lapping compounds to adjust the fit as needed.

Always use a greasing compound that is waterproof to help prevent the intrusion of water into the shaft/propeller system.

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Choices for Aluminum Propellers

Two very common metals used for casting boat propellers are stainless steel and aluminum, with aluminum being the most commonly used metal for this purpose. Boating enthusiasts are divided in their opinion of the two, with some strongly preferring aluminum props over any other kind. One major advantage of aluminum propellers is their affordability; boaters can often buy them for a fraction of what a stainless steel propeller in the same size range would cost. Aluminum propellers are also highly portable, in part because the nature of aluminum makes them lightweight. In addition, these propellers deliver high performance and are appropriate for a wide range of boating activities.

One caveat about aluminum props, however, is that they must be kept painted in order to keep corrosion at bay.

Michigan Wheel Aluminum Propellers

The Michigan Wheel company, a historically well-respected name in propeller manufacture, offers many different models of aluminum prop. They produce two major lines of such propellers: the Vortex and Michigan Match series.

Vortex propellers from Michigan Wheel feature XHS hub technology and incorporate features such as geometric blades that deliver high performance in part because they are precisely balanced for maximum efficiency in the water. They also look attractive, boasting a powder coat finish that will help to prevent corrosion from forming on the blades or hub. All Vortex props come with a limited lifetime warranty.

Michigan Match propellers feature a hub already pressed in, which means there is no need to purchase an additional hub kit. Michigan Match propellers are manufactured from high-level aluminum alloys that help the prop stay in excellent condition for many years.

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Excellent Ski Propeller Choices

ski propellersSeveral different kinds of ski propellers exist to provide a water skiing experience that will be enjoyable for all.  Water skiing requires a powerful motor that can rapidly reach full power, and this requires the right kind of propeller.  Without that, when the water skier yells, “hit it!” he or she will merely be dragged along the surface of the water instead of being able to stand up on top of the skis to slide and skid along the surface.

Ambush Ski Props

The Michigan Wheel line of Ambush ski propellers uses a machining process known as CNC.  This process was developed by Michigan Wheel during the 1980s to guarantee a completely accurate propeller in all specifications and dimensions that will function as intended.  CNC originally applied only to the fabrication of custom propellers intended for large yachts and other luxury vessels. Over time, it has become a standard for many propeller series including the Ambush line.  Michigan Wheel offers a limited lifetime warranty on all Ambush ski props.

Acme Ski Propellers

Acme ski props are manufactured of durable nibral and are 100% American-made.  Available in both three- and four-bladed varieties, Acme also uses a “computer numerically controlled” manufacturing process to ensure optimal fabrication so that stated specifications are completely accurate and match the actual prop.

Dyna Jet Cupped from Michigan Wheel

Another Michigan Wheel ski prop choice is the Dyna Jet Cupped, which is specifically engineered to meet the needs of high-powered boats.  Dyna Jet props are made of nibral, an alloy of nickel, bronze, and aluminum.

The Importance of Pitch

Those new to boating might not have heard of propeller pitch, but is it one of the most important specifications that propellers possess.  Propeller pitch is a basic term used to describe a propeller.  The pitch measurement communicates what kind of performance a boating enthusiast can expect from a given unit. In effect, prop pitch describes how much motion the propeller will move forward during one complete revolution.  For example, a propeller described as having 17″ of pitch would move in a forward direction a full 17″ as a result of the blades making one complete turn.

An Idealized Number

Pitch as it is given in propeller descriptions in an idealized number because it always indicates “perfect pitch,” which refers to the distance a propeller would move forward if it were moving through a soft and stable medium such as balsa wood.  The real world conditions a motor must contend with are far from ideal, however.  The rocking motion of a boat upon the water along with the underwater eddies will usually cause a reduction in true pitch.

Implications of Pitch Figures

Propellers with a large pitch number will be able to supply top speeds that are greater than those are that can be achieved from propellers with low pitch.  As is usually true, however, there are trade-offs to consider.  Better top speed usually means a slower rate of acceleration.  In the same manner, a prop with low pitch will mean that an engine can reach its maximum power at a lower speed.

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Acme Propellers Emphasize Quality

Acme Propellers are completely American-made and utilize U.S. labor for all phases of the development process, including engineering, fabrication, shipping, and verification and inspection.  This is not the primary reason why they are a favorite with boating enthusiasts, however.  Both pleasure boaters and those who use their crafts for business purposes appreciate the high quality and consistent attention to detail that is inherent in Acme Props.

The CNC Process

Acme uses a specialized method for manufacturing their props.  Known as CNC, the process allows line engineers to make tiny changes in any of the specifications of the propellers being fabricated.  Specifications that can be “dialed in” in this way include pitch, cup, and diameter.  The result is an ability to make incremental changes and test for quality until many individual models of boat have an ideal propeller to match, one that helps them reach optimal efficiency.

Acme Propellers are also known for their smoothness of operation.  Available diameters for these inboard propellers range from 12 inches to 13.5 inches with pitch ranging in value from 12.5 to 17.5 inches.  Different degrees of cup are also available.  For example, the ACME-1279, a three-bladed propeller, features 13.5 inches of diameter, a pitch measurement of 15.5 inches, and a cup of .105.  Another propeller with three blades, the ACME-1747, has an identical diameter but offers more pitch – a full 17.5 inches per rotation cycle.  The 1747 model also has a higher cup value at .150.

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Michigan Wheel Inboard Propellers: DJX, DQX, and M-500 Series

The public at large is most familiar with outboard propellers, but as boating enthusiasts know, inboard propellers are another popular choice for watercraft propulsion.  Michigan Wheel makes inboard propellers with three, four, and five blades.

The DJX and DQX Lines

Michigan Wheel inboard props in this series have three blades.  An outgrowth of the Dyna-Quad and Dyna-Jet propeller lines, DJX propellers are designed for situations where there may be limited clearance for the tip.  They also work well with high loads.  Propellers in this line have diameters ranging from 12 to 21 inches.  Some propellers in this series have blades with no cup, while others exhibit all the common amounts of cupping boating enthusiasts look for.

Michigan Wheel inboard props in the DQX series have four blades and range from 17 to 32 inches in diameter.

The M-500 Line

Many boaters prefer the M-500 inboard propeller from Michigan Wheel.  With five blades and diameters ranging from 22 to 44 inches, these inboard props provide a large blade area even in the smaller propellers in the line.  This allows for high performance, even for boats that cannot accommodate large propellers due to clearance issues.

The M-500 is particularly useful in certain situations where water flow towards the propeller is disrupted by the presence of obstructions such as hull appendages, dead wood, or large and / or heavy v-struts.  Indeed, in these situations the M-500 is one of the most popular choices available.  It also helps to reduce engine vibration, which many boaters consider its most advantageous feature. 

Making Sense of Propeller Dimension Figures

When shopping for aftermarket Nissan Boat Propellers for the purpose of improving some aspect of watercraft performance, consumers will probably notice immediately that propellers are often described in terms of dimensions.  At first glance, these dimension figures make little sense.  For example, a certain class of Nissan props may be listed as having dimensions of 12″x 9″.

While these dimensions are those of a rectangle, they also apply to propellers, which are circular in nature.  The educated boating enthusiast knows that the right way to make sense of the dimensions is to know that the two numbers describe two different things.  The first number given refers to the diameter of the propeller and the second number refers to its pitch.

Diameter refers not to the size of the central hub, but instead to the size of the circle that the blades make as they rotate.  Pitch, in contrast, describes the amount of linear distance that the watercraft will move forward as a result of the propeller blades making one complete rotation.  Pitch, however, is an idealized number that treats the propeller as though it were moving through a solid, stable medium such as a soft wood.  The actual distance a boat moves forward is less than the pitch stated because “slippage” occurs due to factors related to the nature of moving water.

Nissan propellers with dimensions of 12″x 9″ are therefore 12 inches across and have a maximum pitch of nine inches.  The actual distance a boat moves forward with such a prop will depend on variables related to boating conditions.

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Why Boaters Choose Stainless Steel Propellers

Three excellent makes for stainless steel props are Apollo, Michigan Match, and Ballistic.  All are manufactured to exacting specifications by the Michigan Wheel company, and meet the needs of a wide variety of boating situations.  To understand why these stainless props are in such demand, consider the advantages that stainless steel propellers offer.

Benefits of Stainless Steel Props

Stainless steel is a metal that can be cast into thin, light shapes while retaining great strength and durability.  This strength means that stainless propellers will maintain their shape and remain completely stiff even when subjected to considerable stress.  Boaters find this an invaluable feature — after all, churning through water for hours at a time is an inherently stress-laden activity that can deform a propeller over time, causing, for example, blades to change their angle relative to the hub.  When this happens, a replacement propeller may be called for — but stainless propellers are tough enough to withstand a great deal of use even in adverse conditions such as stormy weather and rough seas.

Another advantage of stainless steel is that it is non-corrosive by nature; hence, it does not need to be kept fully painted at all times.  Since most boating enthusiasts live a busy lifestyle on and off the water, a prop that needs less maintenance is a definite advantage.

It is true that stainless steel is more expensive than some of the alternatives are, but the old saying of “you get what you pay for” is certainly true in this case.

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