Prop Work

[Nigtmare]

With all the free time that I have, I thought I would try to learn how to pitch a prop. I got a pitch gauge from Franco and it was collecting dust for all these years. After reading the instructions a few times :lol: I finally understand how this thing works. So I got my 40 hydro props out and I started checking them out. I have all kinds of different readings from different props. For instance my 1460 was giving me a 2.8 and other props would give me different pitches right up to 3.9. My questions are:

1:Where on the prop do you take the measurement from.

2:How far to the back of the prop do you let the gauge go.

3:What pitch do you give to different series of props for instance a 14 series, 16, and so on.

4: How do you cup a prop? Is cupping considered pitching?

I cant think of anymore right now. I'm sure theres other questions as well so feel free to add to the question list. I know lisbo site has a prop topic and I have read it. I just dont understand all of it, so maybe some people over here can explain it a little better. Mark I expect you to give an answer or two

Thanks and get involved!

Nick

 

[Chris Wood]

Nick,

Alot of people say to go 70% of the blade dia out.. meaning measure the blade dia.. take 70% of that and then measure out from the hub out and put your cup there.

I personally don't mess with that. As for where.. depends on what your boat needs and how much.. I have pitched props on the trailing edge as well as further down the prop.. not only that but out on the edge of the blade.

You will find a 1000 ways from everyone.. I used to try and do what everyone said. i finally just played with them and distroyed dozens of props till i figured out what and why it is doing what it is doing and learned from that. I an by NO MEANS A PROP GUY, i just learned for my own boats.

the octura series have a low pitch progression for the most part..

that is why for instance if you took at 1450 stock out of the box and put it on a hydro it will hop... You add cup and that brings the progession closer together.. making more lift in the process.. ( if i am wrong please correct me )

as for cupping.. i use a set of pliers with balls from ball bearings solidered to the jaws. I would like to try a set with nylon balls on it sometime to help with marring the surface of the prop. on the bottom of the jaws i dremeled the contour of the back side of the prop, not perfect but close to fit different props.

like i said am no pro.

hope i answered some of your questions

chris

 

[Jerry Wyss]

It sure would be nice to have a video on this subject by a good prop man,, wouldn't really have to be

that long to shed some light on this subject. I'm definetly in the dark outside of X series Octura props.

Chris, I'm not sure but doesn't pitching the trailing edge of say a 1455 reduce the lift? Jeez, here I go

making an arguement already.

 

[Mike Hughes]

Most people measure their props at the 70% mark. I do. Usually it is a guesstamation. So to exactly reproduce it you must know where it was. This is important if you are trying to rebuild a mapped prop. It also changes if you are trying to measure a different part of the prop. Most of the time I spend bending props it has nothing do with mapping. The motor may not be pulling the prop down the shute the way I like it to. So I may take out some pitch to let it rev more. It is jsut one more way of tuning a boat during a days racing. The amount of change is no more than .2 difference. from the original setting.

There is no magical pitch setting for any prop. As to where you pitch/depitch the prop all depends on what you would like it to do. You basically have a cone of water coming off your prop on course. The smaller the cone the more forward thrust you have. How that water comes of the prop depends on the shape. I have take some lift out of props by pitching the leading edges of 1400 & 1600.

Cupping a prop is pitching a prop. Just in a more drastic measure. This was how I did before I started to use a pitch gauge. You can be more precise by pitching than cupping. Pitch progression is drastically changed when the water reaches the cup part. By pitching you spread the pitch over a larger area. You don't see any motorcycle jumps with a bunch of cup at the top of the ramp. It is a nice progression up the ramp until the motorcycle leaves the top. Works great on boats too.

I think they call it a black art because there are some many variables when it comes to pitching a prop. It is the one thing that most people can not do. They can move the pipe, lean the needle, change the prop, easily to try and tune their boat. I have been doing this for 17 yrs. and there is only one way to find these out. By trying to pitch and then test. Each boat is different so there are no easy answers. You can read all you want for the basics. Now to make something really work good you have to test. How do you think Andy (or any of the prop builders) have become the way they are today. He has try it. Using his past experience to make suggestions.

Marty's site gives you a good background on what to do. Now go out there and wreck some props. LOL Good luck with bending your props.

Mike

 

[shoboat]

Nick,

You are opening a can of worms here. :lol:

1.)You can measure a propeller in many different areas,what are you looking for?

L.E. pitch? T.E.cup? C.O.B. pitch?T.E.pitch?Pitch Progression?

2.)I use a Steve Wood's gauge so I can't help you here,ask Frank. :lol:

3.)Pitch is different for every set up Nick. It will vary greatly on the pipe,motor,boat type,driveline system,etc.

4.)Cupping is very easy to do,but where you do it is what makes or breaks the propellers performance. Most

use .7 radi for a baseline measurement.

5.)Cup is totally different than pitch.

6.)Pitch progression is another topic,but Chris it is just the opposite of what you think it is. In a nutshell, the pitch

progression is the difference between the L.E. pitch and T.E. pitch. It will vary,but I can share with you, the less

you have the faster you can go to a point,there are many other variables in the equation. :lol:

7.)Cup takes away a certain amount of lift from a propeller,as does backcutting the T.E. of the propeller. So when you

cup a propeller it does a few different things to your set up. It will reduce your lift,slow your RPM,and narrow your

thrust cone quite a bit. A little cup can help out in different areas,but it is not the only way to increase the performance

of your set up.

8.)I am not a typist and it is getting late. So Nick just give me a call sometime, and I will be happy to help you out more.

231-590-3023

9.)Mercury Racing Web Site is a great place to learn more @ (http/www.mercuryracing.com) I think this is right.

10.)Good Night! :lol:

I hope this helps you Nick :lol:

Mark Sholund

 

[Chris Wood]

Hey jerry,

Yes you are right, i had a brain fart last night..

Nick,

Like mark said you can put cup anywhere for the most part on the prop..

Just mess with a prop for a while until you can find what works for you.

That is what i did. I got tired of paying big money from people that do props.. Forced myself to do it.. Plus i now know what changes to make to the blades.

chris

 

[Joe Warren]

Nick,
You are opening a can of worms here. :lol:

1.)You can measure a propeller in many different areas,what are you looking for?

L.E. pitch? T.E.cup? C.O.B. pitch?T.E.pitch?Pitch Progression?

2.)I use a Steve Wood's gauge so I can't help you here,ask Frank. :lol:

3.)Pitch is different for every set up Nick. It will vary greatly on the pipe,motor,boat type,driveline system,etc.

4.)Cupping is very easy to do,but where you do it is what makes or breaks the propellers performance. Most

use .7 radi for a baseline measurement.

5.)Cup is totally different than pitch.

6.)Pitch progression is another topic,but Chris it is just the opposite of what you think it is. In a nutshell, the pitch

progression is the difference between the L.E. pitch and T.E. pitch. It will vary,but I can share with you, the less

you have the faster you can go to a point,there are many other variables in the equation. :lol:

7.)Cup takes away a certain amount of lift from a propeller,as does backcutting the T.E. of the propeller. So when you

cup a propeller it does a few different things to your set up. It will reduce your lift,slow your RPM,and narrow your

thrust cone quite a bit. A little cup can help out in different areas,but it is not the only way to increase the performance

of your set up.

8.)I am not a typist and it is getting late. So Nick just give me a call sometime, and I will be happy to help you out more.

231-590-3023

9.)Mercury Racing Web Site is a great place to learn more @ (http/www.mercuryracing.com) I think this is right.

10.)Good Night! :lol:

I hope this helps you Nick :lol:

Mark Sholund

Great Answer Mark, Nick, Feel lucky Mark shares this Info with us, The Prop work is Business for Most & was Not talked about openly for years. You would have to travel to Big events to see racers seeking to find the edge or tweaking for SAW or fast Oval trials @ the Nats to pick up on the Tips, I have found ever boat type has its favorite Prop design, Very few props are alike, What your learn the hydro likes? May not apply for the Mono`s. Different Motors favor diff design props & A light Boat lets a Great prop excell. If you can afford to let the prop guys do your Prop work. They will get you 90 percent there. Its up to the boater to find the last 10 percent. Mark & Andy Openly provide a Prop service, Martin Davis had a Ton of great info But you wou have to boat with him to appreciate the knowlede, Martin was Good at observing a boat then tweaking the prop for speed & any other problems the boat had... he had a lot of hands on @ the pond over the years.

 

[steve wood]

Hey jerry,
Yes you are right, i had a brain fart last night..

Nick,

Like mark said you can put cup anywhere for the most part on the prop..

Just mess with a prop for a while until you can find what works for you.

That is what i did. I got tired of paying big money from people that do props.. Forced myself to do it.. Plus i now know what changes to make to the blades.

chris

as i recall it was more like "i have enough to do around here, i'll make a gauge and you can figure out how to work on props yourself" :lol:

 

[Chris Wood]

Hey jerry,
Yes you are right, i had a brain fart last night..

Nick,

Like mark said you can put cup anywhere for the most part on the prop..

Just mess with a prop for a while until you can find what works for you.

That is what i did. I got tired of paying big money from people that do props.. Forced myself to do it.. Plus i now know what changes to make to the blades.

chris

as i recall it was more like "i have enough to do around here, i'll make a gauge and you can figure out how to work on props yourself" :lol:

Lol ya and just think of all the MONEY I have saved you over the years lol!!!!

seriously nick,

there are two ways of looking at it.. learn yourself, or pay someone.. just remember if you pay someone, they don't always have the best idea for props since it is in all reality a estimated guess un less they have tested with boat x and motor z.. even then you really need to be there to see the boat and what it is doing.. TIME AND TESTING.. that is what it takes.

chris

 

[Nigtmare]

It looks like we're having a good thread going and I think that a lot of people have the same questions as I do. Mark, I guess I did open up a can of worms but theres alot of people that would like some of those worms. By you giving us some tips here, it will get people to try different things. Maybe that will be a good thing for you, because they will screw up some props, appreciate your work more, and learn a few things. It would be a lot better if we knew more things about props because when your at the pond and the only thing you can actually do is adjust your pipe and your mixture. Most of the time this will not do what your after. So I understand that the sweet spot is at .7, now do you put the pitch right across the whole blade? or just at that point? Do you try to make it more gradual, or you just want a pot hole at that point. I never knew that there was a pitch considered at the L.E. of the prop. :lol: Is that where you get the lift? When you pitch the L.E., does that give you more lift? I have seen people that have props made with all types of weird cuts at the T.E. What effect does that add? I have a prop from the early 80s, a 1465 with a "Texas Cut" whatever the hell that means. I know the blade is cut straight at the outer edge and to tell you the truth, sometimes its the best prop that I can put on a boat. Will a 40 and a 21 size prop have the same amount of pitch and will those props perform the same? I guess thats about it for now. The bottom line is when i go testing, I want to be able to go there and get the most out of my pipe, engine, and prop. The only way to have a competitive boat, is to tackle all aspects of the hobby. Joe, for me its not about the money. I can pick up the phone and order one from mark, or buy props here at the forum, but when I order from mark, mark doesn't come along with it. :lol:

Nick

 

[Ron Jefferson]

9 times out of 10 the fast guys at the races are the ones that have figured out the prop thing. I know it takes a complete package to have a really good heat racing boat. However, I have found personally that the prop gives the biggest performance advantage above any other modification to the motor, pipe or whatever. Once you get everything else right the prop can be good for 6-10mph by itself. Even a really well modded engine over stock doesn't get you that kind of speed. The rest of the posts are right on that say test, test, and more test. I've taken a whole season to get a boat where I'm happy with it's performance. The tough part is when you get it to that point, keeping it there can be a bunch of work too.

Also... If you have a prop that's totally awesome on your boat. It might be a piece of crap even on something similar. Or, try duplicating the best prop in your box once it's modified. Not an easy task for sure. They'll always be slightly different in performance. You may not even come close.

Ron

 

[Chris Wood]

9 times out of 10 the fast guys at the races are the ones that have figured out the prop thing. I know it takes a complete package to have a really good heat racing boat. However, I have found personally that the prop gives the biggest performance advantage above any other modification to the motor, pipe or whatever. Once you get everything else right the prop can be good for 6-10mph by itself. Even a really well modded engine over stock doesn't get you that kind of speed. The rest of the posts are right on that say test, test, and more test. I've taken a whole season to get a boat where I'm happy with it's performance. The tough part is when you get it to that point, keeping it there can be a bunch of work too.
Also... If you have a prop that's totally awesome on your boat. It might be a piece of crap even on something similar. Or, try duplicating the best prop in your box once it's modified. Not an easy task for sure. They'll always be slightly different in performance. You may not even come close.

Ron

Ron you hit the nail on the head man.. I had a 67 prop 4 years ago that would run all day at 92 mph.. Do you think i can get that same prop to do that now?? I have measured that thing to death.. copyed and copyed and copyed.. still about 2-3 mph different.. same prop. dia, pitch bla bla bla..

You someone also made a good point about taking the prop guy to the lake.. That is why i started to do my own.. I used to get props from andy.. spend 60 plus dollars.. and if it wasn't right, i either got another one or sent it back to have him redo it..

I think the main reason people don't mess with props is because they are a pain, but a nessisary evil..

chris

 

[Nigtmare]

9 times out of 10 the fast guys at the races are the ones that have figured out the prop thing. I know it takes a complete package to have a really good heat racing boat. However, I have found personally that the prop gives the biggest performance advantage above any other modification to the motor, pipe or whatever. Once you get everything else right the prop can be good for 6-10mph by itself. Even a really well modded engine over stock doesn't get you that kind of speed. The rest of the posts are right on that say test, test, and more test. I've taken a whole season to get a boat where I'm happy with it's performance. The tough part is when you get it to that point, keeping it there can be a bunch of work too.
Also... If you have a prop that's totally awesome on your boat. It might be a piece of crap even on something similar. Or, try duplicating the best prop in your box once it's modified. Not an easy task for sure. They'll always be slightly different in performance. You may not even come close.

Ron

Ding..Ding.. Bingo.....

 

[Jerry Wyss]

:huh: so no video,, youtube?

 

[Nigtmare]

:huh: so no video,, youtube?

Jerry.. Mark is working on it

Go Mark Go

:lol: :lol: :lol: :lol: :lol: :lol:

 

[Terry Keeley]

Hey Nickos:

I measure the diameter with calipers, then calculate 3/4 of one blade and set Frank's gauge to measure there. I take 2 readings, one from TE to as close to the LE as possible, that I call average pitch. For cup I measure the last 15 degrees to the TE, it's often quite a lot more than the average.

To get a better reading you could replace the tip on the indicator to one that's more pointed, here's a link:

http://www.jlindustrial.com/catalog/produc...ktosearchpage=Y

From my testing cup lowers the lift on a prop and tends to keep it "hooked up" better.