Prop Pitch Checker Instructions

[qzmwzz01]

I was sorting out some old equipment as I have been out of boat racing for 20 years (thinking of getting back into Stock Outboard) and ran across this prop pitch checker. I think I purchased from "C Modified Racing Service" (but may be mistaken) Anyway, I had a few sheets of instructions on how to use it and of course I can't find them. Does anyone recognize this pitch checker and can provide intructions on how to use it and who made it ? Thanks, Tom Wysocki (former 177M - ASR Michigan)

[Big Don]

Want to sell it?

[qzmwzz01]

not selling - just need to remember how to use it......

[Islandmon]

Sorry to say I can't help you with your problem Tom. That said once you do get it figured out can I barrow it................just kidding . Try contacting Ron Hill's web site @ www.boatracingfacts.com, my guess is that if anyone can help you he can. I see we are sort of neighbors send me a PM and we can chat a bit. Would love to see another racer back in the fold.

Sam,
87M

[BabcockBros38A]

hope this helps

That appears to be a copy of a "SKID D0" pitch gage that was made in

Dayton Ohio, as far as I know they were popular during the 50's and
Later as well,

It also has patent pending stamped on it. I think Brinkman's copy

operates the same way. Here are my instructions and pics as well.

The older version is for 2 blades. I see Harry's is for 3 blades both use the same principles.

For lefthanded props:

First set the Top sliding pointer (the one with the scale on it), to aproximately at about 70% to 80% on the diameter. (refer pic #1)

Turn the stop knob counterclockwise until it hits the stop pin.
(See pic #1)

Put the prop on the shaft and tighten slightly.

Now set the pointer to contact the prop just at the edge inside cup if
cupped (See pic #2)

Now move Bottom pointer to align with the nearest whole number on the
scale. (See pic #3)

Now Rotate Stop Know clockwise to stop pin (See pic #4)

Slide top sliding pointer in until it just makes contact with the
forward portion of prop Blade (See pic #5)

NOW, Read amount of travel pointer made. That will be the amount of
pitch in inches.(pic #6) sorry for the blur!


Most Skid-do gages used a Starrett #610N narrow scale about 3 inches
long and graduated in 1/64 and in inches.

1/8 inch is equal to 1" of pitch and 1/64" is equal to 1/8" of pitch
so if read 1 1/4 inch of travel you had 10 inches of pitch.

Right hand props use the same stops, just in opposite order.

Hope this helps

[bill van steenwyk]

have written instructions available (I think)

I had and used a gauge like this for many years. Just sold it last winter or early spring. I kept a copy of the written instructions so could consult with the buyer if required. If you can't get anything to happen with the above listed instructions, let me know and I will see if I can find the copy and either e-mail or send you something.

[qzmwzz01]

Thanks for the quick response - starting to ring a bell but no wonder I could not remember how to use it.

[ZUL8TR]

pitch tool

Thanks for the quick response - starting to ring a bell but no wonder I could not remember how to use it.

Note that these type of gages typically provide the average pitch from the leading edge to the trailing edge at a selected radius usually selected at 70% of the radius from the center to the max blade tip. Surfacing propellors have variable pitch from lead edge to trail edge. Would need to check all the blades to get overall average pitch of prop at the selected radius. Other radius locations could also be measured to see pitch variations.

[qzmwzz01]

One more question on the rotation "stop" fixture

one more question - my set up has rotation "stop" fixtures for both two blade and three blade props - the two blade has two small slots and two larger slots and the three blade has three small slots and three larger slots..do I use the small or the large slot when rotating the prop as they will give different answers since the prop rotates more in the larger slot ?? p.s The three blade prop was from Roy Minor - it did not have enough "bite" for the ASR but I held onto it because it is an absolute piece of artwork..

[bill van steenwyk]

slots versus wider/narrower

If I remember correctly, the wider slot is used if you are using 1/8" scale and narrow slot when using 1/16" scale. Again if I remember correctly the narrower slot will allow more measurements across the blade as the blade will not rotate as far and will allow more areas of the blade to be checked for pitch. If you only check one place on the blade (middle for example) you are only getting average pitch as another poster mentioned. You can check leading, middle, and trailing edge pitch, and also cup by using the narrower slot and the smaller measurement on the scale.

[bill van steenwyk]

one more thing regards this pitch gauge

You may or may not get the same pitch readings with this gauge (or any other) by checking the same prop on different style gauges. What this gauge will do for you (just like any other) is give you the base line of the prop you are checking and then if you check different props ON THIS SAME GAUGE you can determine whether you are gaining or losing during the testing procedure also using a tach and speed measuring device.

Don't fall into the trap of having your Buddy give you the measurement of any prop on his gauge and then measuring it on yours if it is different than yours, and then getting confused because his gauge does not measure the same prop the same pitch as yours, just as you won't find out much by changing to a different tach and speedometer each time you change props. The gauge works well for COMPARISON PURPOSES while testing to see if more or less pitch/diameter/cup changes the way your boat handles and runs.

[qzmwzz01]

Thanks Bill - makes perfect sense - I'll try both slots in the middle of a blade with both scales. Should get similar results. If indeed this gage was built by Harry Brinkman I have a piece of history and will treat it as such...