Visit us at the METS trade show in the Amsterdam RAI Center 11/13/12 thru 11/15/12

Global supplier Turning Point Propellers 

Booth 11.409

What is Propeller Diameter?

Propeller diameter is the distance across an imaginary circle that a spinning propeller makes. It can be easily determined by measuring the distance from the center of the hub to the tip of one of the blades and multiplying that number by 2.  On a four blade propeller you can directly measure the diameter from tip to tip on opposing blades.

         

Diameter is the first number on the size of a propeller: a 14”X19” is a 14 inch diameter propeller with a 19” pitch blade.  Many propeller manufacturers change diameter as the pitch increases or decreases: as an example, a typical size range for a Mercury Alpha One I/O would be 14-1/2”x19”, 15”x17” or 15-1/2”x15”.  As the pitch decreases, the diameter often increases.

Diameters between different propeller manufacturers may vary slightly. On Turning Point propellers, this is due to more aggressively engineered  designs on blade geometries. As an example, Turning Point offers a 14-1/4” diameter propeller for most V6 outboard and I/O applications. Other manufacturers propellers may range from 13-1/2” up to 16” for this same engine. These diameter variances do not affect your performance as much as the pitch and overall design. In other words, you do not need to match the diameter of your current propeller when you are purchasing a new one from Turning Point. Larger diameter propellers - 15" or 16" diameter - are designed for larger boat applications - 23 ft +. These larger boats need more blade area to carry the hull properly and push more water.

Consult your Turning Point Propeller dealer to learn about how our propellers will improve the performance of your boat. Turning Point has been engineering, manufacturing and marketing high-performance, pleasure craft aluminum and stainless steel propellers for over 15 years. Our innovative products are available worldwide through an extensive family of dealers and retail outlets, which can be found on the "Find a Dealer" section of our website www.turningpointpropellers.com

Contact  Turning Point Propellers at  847-437-6800 or at sales@turningpointpropellers.com

What is Propeller Diameter?

By:  TP.  Engineering

Turning Point Propellers, Inc.Published:  2012-10-12

Boaters Use a Checklist Before Getting Underway

Boaters Use a Checklist Before Getting Underway

by: U.S. Coast Guard Auxiliary Public Affairs

http://www.uscgnews.com/go/doc/4007/1510923/

How to Trim My Boat - Step 1

Trimming is typically thought of by most boaters as the action that maximizes hole-shot and speed of a boat.  But the scope of this skill goes well beyond momentum... In this multi-part article we will cover the basics of trimming a boat for maximum efficiency and safety.

STEP 1: Available Technology for Improving Boat Attitude

If your boat does not have the hardware covered in this article contact a dealer for propeller or aftermarket options.  Here are some of the typical tools used for trimming a boat  and changing its attitude while under way.

Trim Tabs:  These installed accessories (commonly called “ Bennetts” if hydraulic, also available in electric actuation from various manufacturers) lift the stern while lowering the bow, and are also used for adjusting lateral balance.  Once the tabs are raised above the bottom of the hull they no longer affect the fore-and-aft attitude or heeling to port (left) or starboard (right).

Outdrive Trim (Outboards and Sterndrives I/Os):  Actuating the hydraulic lifts installed on these drive components changes boat attitude similar to trim tabs.  If set in the "down" position, they cause the stern to lift while lowering the bow.  They can also be adjusted “up” which lowers the stern and affects bow rise.   Outdrive trim is primarily used for fore-and-aft attitude adjustment and to increase propeller running angle for improved top end speed.  In multi-engine applications the outdrive trim can adjust lateral balance. This is not the preferred method for side to side adjustments and a loss in efficiency can be expected.

Propellers:  Depending on design, number of blades, and geometry a propeller has the potential to increase both bow and stern lift (fore-and-aft attitude).  The rake angle of a propeller blade plays the biggest role in fore-and-aft attitude over any other prop attribute.  Bow lift can be expected if the blades of a propeller in relation to its barrel slant away from the boat (positive rake angle), while less rake angle increases stern lift.  An increase in blade count, diameter, and surface area also increases stern lift.

Hydrofoil Stabilizers:  Another aftermarket installed accessory item, these change fore-and-aft attitude only.  They are mounted to the out drive's cavitation plate located just above the propeller.  The majority of hydrofoils are designed to increase stern lift to correct for underpowered engines or poor performing propellers.

Balance Tanks / Bladders:  Aftermarket installed accessory items, these are typically used to help balance a boat as fuel is consumed and to increase wake size for water sport enthusiasts.  They are generally placed near the aft (rear) of the boat.  

Passengers and Equipment: Movable ballast can be used to help further balance the boat.  Before adding these additional variables, it is best to master trimming your boat.

With the large variations of possible environmental conditions, boat hull types, and power configurations in the market there is no "one size fits all" guide to achieving ultimate trim.   With some experimentation and the helpful services of a knowledgeable Turning Point dealer, you can achieve a safe, smooth, and fuel efficient ride on just about any boat.   See future articles on “How to Trim My Boat”

Consult your Turning Point Propeller dealer to learn about how our propellers will improve the performance of your boat. Turning Point has been engineering, manufacturing and marketing high-performance, pleasure craft aluminum and stainless steel propellers for over 15 years. Our innovative products are available worldwide through an extensive family of dealers and retail outlets, which can be found on the "Find a Dealer" section of our website .www.turningpointpropellers.  Contact  Turning Point Propellers at  847-437-6800 or at sales@turningpointpropellers.com

How to Trim My Boat - Step 1 - Available Technology for Improving Boat Attitude

By:  TP.  Engineering

Turning Point Propellers, Inc.Published:  2012-08-22

Checking for Propeller Damage

If you use your boat, it is inevitable that you will eventually strike something with your propeller.   Just running through the water, the propeller is being impacted by a multitude of un-seen floating debris hovering a few feet below the water surface.  Whether you hit something hard or graze the bottom softly, you can change the blade geometry, bend or break them off completely, or chew up the edges.  A damaged propeller will perform poorly, have decreased fuel economy, increase vibration, and may lead to engine damage.  

The propeller is what moves your boat.  Once you get the best propeller for your rig, you want to take care of it.  Not only does the correct propeller get the boat on plane well, accelerates, corners, and lifts well, it also helps you save fuel.  But only if it is in good shape.

While running your boat, if you notice a change in RPM or an increase in vibration, or feel the boat hit something (or think you might have hit something), stop the boat, turn off your engine, and raise your outboard or outdrive as high as it goes to look at the skeg and propeller.  Make sure you remove the key and lanyard stop clip before approaching the propeller or entering the water to inspect the outdrive.

Check the propeller blade edges for cuts, notches, bent surfaces, or missing material.  Inspect the skeg - is it bent, broken, or missing?  All of these damages can result in significant decreases in performance or safe running conditions.  If you see any major damage we recommend you replace the propeller as soon as possible.  Running a severely bent propeller for a period of time can result in lower unit seal or bearing damage due to excessive vibration.  Running a boat with a bent or missing skeg can have a significant impact on boat handling and maneuverability.

It is imperative as part of your end-of day checklist to inspect the condition of the propeller and skeg.  Repair or replace the damaged item immediately, so your next outing doesn’t become an expensive and time consuming lower unit repair.

Your local Turning Point dealer has stock of a variety of propeller diameters, pitches, blade designs, and materials that will meet your needs.  For help determining the correct propeller for your boat and engine combination or locate your local dealer, consult the online Prop Wizard by Turning Point at www.turningpointpropellers.com. Prop Wizard is the only pitch calculating tool in the industry, and can help you get the most out of your boat's performance.

Checking for Propeller Damage

By:  TP.  Engineering

Turning Point Propellers, Inc.Published:  2012-07-25

Selecting the Right Pitch

The RPM your engine runs at wide open throttle (WOT* click to learn more) is determined by the pitch of your propeller.  With too much pitch, the engine won't be able to turn the propeller in the proper RPM range.  Too little pitch and you could over-rev and possibly harm your motor.

Using a propeller that gives you the correct WOT RPM range will give you a better hole shot, better acceleration and top end, and improved fuel economy.  You will get the best performance out of your boat when you are running your engine in the correct RPM range.  

How do you select the correct pitch for your boat and motor combination?  First, ensure you have a working and accurate tachometer.  You will need to run your boat with your current prop at full throttle (without exceeding your engines recommended max rpm) and best trim angle with a normal load (see upcoming article about engine mount and trim angles).  At full throttle, note the RPM on your tachometer.  Compare this number to the WOT number for your engine.  

For example: If your engine WOT range is 4400 to 4800 RPM,  and your test run shows you are  turning 4100 RPM at max throttle, your engine is running outside of the manufacturers RPM range. 1 inch of pitch usually equals 200 RPM, so for this instance installing a propeller with 2 inches less pitch would increase your RPM to 4500 (200X2=400), which is now inside your WOT range. Remember, adding pitch reduces RPM, subtracting pitch adds RPM.

As another example: If your engine WOT range as specified by your manufacturer is 4400 to 4800 RPM,  and your test run shows you are turning 5000 RPM (do not run the engine higher than your manufacturer's maximum RPM for more than a few seconds), you need to add pitch to decrease your WOT RPM.  If you install a propeller with two inches more pitch, you may reduce your WOT RPM by 400 RPM (200X2=400).  With this new propeller installed, your boat test should now result in a WOT of 4600 RPM, which is now inside your recommended range.

Take note of your current propeller diameter and pitch.  From the examples above, you will need to purchase a new propeller that has a different pitch based on your test findings.  If you are currently running a 17” pitch propeller, and need to add 400 RPM, then you will need to purchase a 15” pitch propeller. If you need to subtract 400 rpm, then you would purchase a 19” propeller.  Different blade numbers, material and brands may affect the WOT RPM.

Your local Turning Point dealer has stock of a variety of propeller diameters, pitches, blade designs, and materials that will meet your needs.  For help determining the correct propeller for your boat and engine combination or locate your local dealer, consult the online Prop Wizard by Turning Point at www.turningpointpropellers.com. Prop Wizard is the only pitch calculating tool in the industry, and can help you get the most out of your boat's performance.

*Please also refer to “What does WOT Means” article.

Selecting the Right Pitch

By:  TP.  Engineering

Turning Point Propellers, Inc.Published:  2012-07-18

What is Propeller Pitch?

Propeller pitch is the theoretical forward movement of a propeller for one revolution, assuming that there is no prop slip. For example, a 21 pitch propeller will theoretically move 21 inches for every revolution. 

The second number listed in a propeller size is the pitch (Ex. 14 1/4” X 21”).

When selecting a propeller pitch for your boat, it is important that the propeller runs at the upper end of your engines wide-open-throttle RPM range. If you want your RPM's to increase, go down in pitch. To decrease RPM's, go up in pitch. As a general guide, for every 2" of pitch, RPM's will change approximately 400 RPM's. 

Related Articles:  What does WOT mean?

Selecting the Right Pitch

 

 

 

What is pitch?

By:  TP.  Engineering

Turning Point Propellers, Inc. 
Published:  2012-07-11