Identify Prop Pitch

[beshears]

Does anyone have a way to measure a prop to determine the pitch?

[DeanFHobart]

Rundquist Propeller

Go To:

www.rundquist.com/

Our Mailing address:
Rundquist Propeller Tools, Inc.
3951 D Mercantile Ave.
Naples, FL 34104 USA

Phone:
(239) 261-7909

They sell pitch and rake guages.

Good Luck.

[sam]

If you bring it to a race there are a number of racers that have pitch gages.

I believe Ron Hill sells pitch gages for $170, maybe a bit more. He puts them on eBay once in a while

Props can actually be measured by hand, but it is a tedious and intricate process involving angled cutting wedges to fit the prop, measuring the angle and converting it by a bunch of math

If you have several props of known pitch, you can cut wedges and compare the angles ... comparing knowns to the unknown, you can usually at least figure out whether it has more or less than the props that are known in your collection.

[ZUL8TR]

Measure prop pitch

Does anyone have a way to measure a prop to determine the pitch?

Here is a start to understand the basics. Just use the tabs in the link

http://sites.mercurymarine.com/porta..._schema=PORTAL

Note that pitch is an ellusive bugger because the surfacing props we use have pregressive pitch from the leading edge to the trailing edge at a given radius therefore it depends on the tool used and where on the blade it is measured. Some measure at the 70% radius at one point some measure several points and average, and there are others so pitch numbers can be confusing. What is really needed is the overall average pitch of the prop and this requires many measurements. The pitch at a point formula is very simple (I can provide if you want) but the procedure can be tedious. The key is a consistent measurement procedure with the same tool. Then you will have a good relative means to compare different props.

An indirect method for pitch determination is obtained by getting the rig on the water and with: a tach, gps or other speed measureing device, known gear ratio of lower unit and calculate the pitch from:

http://www.rbbi.com/folders/prop/propcalc.htm

In this method you need an estimate for slip and that makes the calc difficult to get accurate pitch determination. However the formula is useful but the results are usually not repeatable because of uncontrolled conditions like: wind, temp, current, speed measuring accuracy, etc.

To see results for no slip just use Slip = 0.01 as the minimum allowed in this calc

Gear ratio = number of teeth on the drive and prop shaft gears. Example on the Yamato Y80 the ratio is 16/14 = 1.143

To hand calculate theoretical speed the no slip formula is:

Speed (mph) = Engine(rpm) x pitch (inches)/(1056 x gear ratio)